Wide-field InfraRed Surveys: Science and Techniques

Talk Abstracts

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Roberto Abraham ( University of Toronto )

Title: WFIRST-AFTA Science Beyond the Local Group

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Abstract: Anybody with two neurons to rub together can see that the extragalactic science programs proposed for WFIRST-AFTA are exciting. But which are the most compelling? And which will resonate most strongly in an optimistic future filled with photons from the LSST, JWST, Euclid and 30m-class telescopes? In this talk I'm going to try to highlight the unique aspects of WFIRST-AFTA for "beyond the local group" extragalactic science. I'm also going to attempt a rather controversial exercise: I will present a polite yet still opinionated/honest (but no doubt still hugely biased) personal ranking of the one page guest observer science ideas presented in Appendix A of the Science Definition Team's report for the observatory. To foreshadow this: some of these are "meh", but most are quite good, and quite a few are spectacular.

Louis Abramson ( University of Chicago )

Title: How Structure Speaks to Star Formation: New Insights on "Nurture" from WFIRST-AFTA

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Abstract: Which factors most affect galaxy star formation histories is unknown, but environment must play a role. Recent work of ours from the z ~ 0.4 IMACS Cluster Building Survey suggests this role is to suppress star formation over Gyr -- not radically alter evolutionary trajectories -- but data at redshifts where galaxies are still growing rapidly in halos of all sizes are needed to truly determine the nature and extent of environmental influence. WFIRST-AFTA will provide these data. Its combination of grism spectroscopy and wide-field imaging will enable the construction of well-defined, statistical, field, group, and cluster samples at 1 < z < 2. Further, the depth and resolution of these data will support the spectro-morphological classification/characterization of galaxies in these environments, especially the critical star-forming population. By providing such homogenous, high-quality data at all spatial scales, WFIRST-AFTA will allow us to assess the galaxy--environment connection in unprecedented ways, yielding new insights into how the growth of structure shapes the growth of galaxies over cosmic time.

Phil Appleton ( NASA Herschel Science Center/Caltech )

Co-authors: Jeff Rich; Katherine Alatalo; Sabrina Cales; Ute Lisenfeld; Kristina Nyland; Lisa Kewley; Mark Lacy and Ray Norris
Title: Searching for the turbulence/shock dominated galaxies with WFIRST's GRISM at 1.8 < z < 2.0

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Abstract: The WFIRST/AFTA grism will be able to take spectra of galaxies in the wavelength range 1.35 to 1.95 microns with a spectral resolution of 700-900. At galaxy redshifts of 1.77< z < 1.97, the epoch of galaxy disk building and maximal cold accretion, BOTH the [OIII]/H-Beta, and [OI]/(H-alpha+[NII]) emission-line complexes fall within the observing window. Based on a study of low-z galaxies in the SDSS, we have identified several subsamples of galaxies exhibiting spectral excitation properties of galaxies likely dominated by shocks: galaxies either experiencing strong AGN feedback and/or other highly turbulent processes. We take subsets of these galaxies, and degrade their spectral properties to that expected from the WFIRST grism, and explore the range of galaxy emission-line excitation that might be feasibly detected with WFIRST in both large survey mode, and pointed mode. In large survey mode (e. g. a 2400 sq degree survey) we would sample a volume of the universe at z = 1.8 of 830 cubic Gpc (380 times the volume sampled by SDSS) to search for extreme LINERs. In individual pointed mode, smaller volumes, but higher sensitivities, would be achieved, targeting dense radio galaxy environments derived from SKA radio surveys. The strategy will allow us to explore the importance of shocked-gas (e. g. like the well known "Spiderweb" proto-cluster at z = 2) over huge volumes of the universe when turbulence and shocks are likely to play an important role in galaxy assembly.

David Ardila ( The Aerospace Coroporation )

Title: Searching for young stars, near and far

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Abstract: As part of the collection of one-page science investigations possible with WFIRST, there are at least three that focus on finding young stars. These consider the challenges involved in (1) finding young objects in the farthest regions of the Galaxy, to understand the role of different metallicity environments in the star formation process, (2) finding the lowest mass objects in the well-known young regions within 500 pc, and (3) finding the nearest young stars to the sun, as part of large moving groups. I'll review these three investigations, with an emphasis on the difficult problem of finding nearby objects. These allow for follow-up using the WFIRST coronagraph, and will reveal the planet forming process in action.

Charles Baltay ( Yale University )

Co-authors: Prof. Saul Perlmutter
Title: Supernova Survey with WFIRST-AFTA

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Abstract: A supernova survey collecting 2700 Type Ia supernovae up to a redshift of 1.7 has been designed in the course of the WFIRST Science Definition Team as an example to demonstrate the capabilities of WFIRST-AFTA. This survey will be described in some detail.

Rachel Bean ( Cornell University )

Title: Weak Lensing

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Rachael Beaton ( Carnegie Observatories )

Title: A Test of Lambda-CDM: Probing the Stellar Age Distributions in Halos Across the Local Volume

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Abstract: Because of their long dynamical times, stellar halos provide unique insight into the formation and evolution of galaxies in a Lambda-CDM cosmology. In particular, each of the stages of hierarchical galaxy formation is preserved -- intact satellites, merging satellites (e.g, streams), and merged satellites (e.g, ‘’smooth halo’’). Halo member stars, however, can have two other origins: (i) stars can be formed in-situ from the initial megalithic collapse of the halo or (ii) stars can be dynamically kicked-up from the disk. Each of the mechanisms will populate the halo with stars drawn from very distinct star formation histories (e.g., those of dwarf satellites, those akin to globular clusters, and those of the disk, respectively). Thus, the stellar age distribution of the halo strongly depends on the relative contribution of each halo formation process and is the most promising observational constraint to tune the dynamical contributions of these processes in state-of-the-art galaxy formation simulations. Current probes of stellar halos are largely limited to their old stellar content -- optically luminous red giant stars, which due to degeneracies on the red giant branch provide no unambiguous leverage on stellar ages. Asymptotic giant branch (AGB) stars, however, have unique signatures in near-infrared color magnitude diagrams for stars of different ages (masses). Thus, AGB stars are powerful tracers for intermediate age (2-8 Gyrs) stellar content. Our NOAO survey program -- the M31 Asymptotic Giant Extended Survey (M31AGES) -- is pioneering the use of AGB stars as age-tracers in a large-galaxy stellar halo, albeit one limited by the observational logistics required for deep (K~23) ground based near-infrared imaging. The wide field, high resolution, and sensitivity of WFIRST-ATCA makes it uniquely poised to survey the halos of nearby galaxies in the near-infrared. Thus, WFIRST-ATCA can not only build the first large sample of global stellar halo properties via the red giant branch (overall size, surface brightness profile, shape, etc.), but can also produce the first age-distribution sample via the AGB/RGB fraction. Such a dataset will be sufficient to provide crucial observational feedback to fine-tune state-of-the-art galaxy formation simulations for the relative contribution of halo formation mechanisms.

Bob Benjamin ( U of Wisconsin-Whitewater )

Title: The Other Half of the Milky Way

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Abstract: If one were to cut the Milky Way in half and throw away the near side, the far side of the Galactic disk would subtend a sliver of the sky about three degrees wide and 130 deg long. Surprisingly little is known about the stellar content on the far side of the disk for three principal reasons: extinction, sensitivity, and angular resolution (confusion). But our understanding of the Galaxy as a complete system requires breaking down the barriers in these categories. We have yet to map the full extent of the bar, to quantify the non-axisymmetric structure of the disk, and to produce a non-axisymmetric mass model for the Galaxy that can be tested with stellar kinematics. I will review the progress that has been made so far in these areas, and what can done with the next generation wide-field infrared photometric surveys.

David Bennett ( University of Notre Dame )

Title: The Promise of High Precision Photometry and Astrometry for Microlensing from Space

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Abstract: The primary advantage of a space-based exoplanet microlensing survey over a ground-based survey is the high angular resolution of space-based images that allow the source and lens stars to be resolved from unrelated stars. This enables high precision photometry of microlensing events with faint source stars at low magnification, which is critical for detecting planets at a wide range of orbital separations. The high angular resolution will also enable the measurement of the host star brightness and the source and host star proper motions in most cases. This will allow complete "solutions" of the planetary microlensing events, yielding host star masses and distances, in addition to the planet-star mass ratio. In fact, this precision astrometry will be required, in order to obtain precision photometry of the microlensing events. The implied requirements on the mission and survey designs are discussed.

Aparna Bhattacharya ( University of Notre Dame )

Co-authors: Dave Bennett
Title: Developing the WFIRST Exoplanet Mass Measurement Method with HST Observations

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Abstract: A crucial feature of the WFIRST exoplanet microlensing survey is the ability to determine the mass and distance of most of the exoplanet host stars and their planets with the WFIRST survey data. For planetary systems discovered with ground-based microlensing observations, this can be accomplished with HST follow-up observations. In most cases, the exoplanet host star can be detected in the HST observations, and when it is detected, we can use constraints from the microlensing light curve model to determine the masses of the host star and its planet. We present results from a HST follow-up observations of planetary microlensing events discovered from ground-based observations to demonstrate the WFIRST exoplanet mass measurement method.

Alan Boss ( Carnegie Institution )

Title: WFIRST/AFTA Exoplanet Science

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Abstract: This overview talk will focus on the constraints on the general theory of planetary system formation that have been derived from recent and ongoing exoplanet surveys, both space- and ground-based, as well as on the constraints that we expect will follow from the launches of TESS, JWST, and WFIRST/AFTA. While understanding the formation of our own Solar System continues to be a challenge, the discovery of thousands of exoplanet systems has forced theorists to expand their models to include a wide range of possible outcomes, i.e., population synthesis (PS) models. The first series of PS models did a reasonable job of reproducing the masses and orbital parameters of the exoplanets discovered by ground-based surveys, but the advent of CoRoT, and especially Kepler, resulted in the discovery of a large population of short-period super-Earths in a portion of discovery space that had been predicted by the early PS models to be a desert, devoid of exoplanets. Theorists have accordingly revised their PS models in order to better match the evolving observed distributions. Exoplanets detected by both transit photometry and Doppler spectroscopy provide mean density estimates, which are equally important constraints for theories of rocky, icy, gaseous, and hybrid planet formation. Kepler K2 and TESS will continue to constrain our knowledge of relatively short-period exoplanets, with the former also searching for distant, free-floating exoplanets, and the latter detecting nearby, transiting super-Earths orbiting low mass stars, exoplanets whose atmospheric properties will be searched through JWST spectroscopy for signs of molecules such as water and carbon dioxide. Ground-based microlensing and direct imaging surveys have already provided needed constraints on exoplanet populations at much larger orbital separations than transit and Doppler surveys. WFIRST/AFTA is expected to make a major leap forward for both of these key discovery techniques. WFIRST/AFTA microlensing is expected to complement the exoplanet census undertaken by Kepler by detecting exoplanets at distances of about 1 AU to 30 AU around distant stars. WFIRST/AFTA coronagraphy is similarly expected to cover new ground in discovering and charactering the atmospheres of giant exoplanets orbiting at similar or even greater separations around nearby stars. The WFIRST/AFTA exoplanet discoveries will constitute the next major advance along the road to the ultimate goal: detecting and characterizing the atmospheres (or surfaces) of potentially habitable, Earth-like planets around the closest stars, a goal that will require the development of ever larger ground- and space-based telescopes.

Rychard Bouwens ( Leiden University )

Title: First Light

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Jo Bovy ( Institute for Advanced Study )

Title: Infrared Galactic Spectroscopy with APOGEE

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Abstract: Spectroscopy is a necessary complement to photometric and astrometric surveys of the Milky Way, because line-of-sight velocities and detailed chemical abundances cannot be obtained in any other manner. I will describe the design and status of APOGEE, a large infrared spectroscopic survey of the main components of the Milky Way, and how it complements and enhances WFIRST science.

Brendan Bowler ( Caltech )

Title: Ground and Space-Based Imaging of Exoplanets Before WFIRST

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Abstract: High-contrast imaging is a valuable tool to probe the outer architecture of planetary systems and directly study the atmospheres of giant planets. Largely driven by advances in adaptive optics instrumentation, observing techniques, and PSF subtraction methods, this field has rapidly advanced over the past 5-10 years and the number of directly imaged planets is slowly increasing. In this talk I will review current efforts to find and characterize giant planets with direct imaging in the era leading up to WFIRST. This overview will summarize the discoveries, instrumentation, ongoing and upcoming surveys, and statistical results from near-infrared imaging to provide context for WFIRST’s complementary visible-light capabilities.

Gabriel Brammer ( STScI )

Co-authors: Pieter van Dokkum (Yale); Ivelina Momcheva (Yale); and the 3D-HST collaboration
Title: 3D-HST: A slitless spectroscopic survey of distant galaxies with the HST grisms

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Abstract: I will present an overview of the 3D-HST program, which is a 248-orbit Cycle 18 HST Treasury program designed to study galaxy evolution at 0.7 < z < 3.2. At these redshifts rest-frame optical emission lines fall within the spectral coverage of the WFC3/G141 grism (1.1 - 1.65 µm). Additional coverage at 0.5 - 1 µm is provided by observations with the ACS/G800L grism obtained in parallel. I will review the survey strategy and some science highlights enabled by the unique space-based near-infrared spectroscopy and I will demonstrate the grism spectroscopy analysis pipeline that turns pixels into redshifts for some 10,000 galaxies at z > 1. The 3D-HST survey covers 600 square arcminutes of well-studied extragalactic survey fields. While this is not wide-field in the context of WFIRST/AFTA, 3D-HST covers an area sufficiently large to sample a broad diversity of galaxy demographics and provides a test case and insights that will inform future space-based near-IR spectroscopic missions.

S. Calchi Novati ( NExScI, IPAC )

Co-authors: A. Gould; J. Yee
Title: Microlensing with Spitzer

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Abstract: The measure of the microlensing parallax is a powerful tool to constrain the lens mass both for single and multiple lens, in particular exoplanetary, microlensing events. Such measurements can then be used to infer the single-lens mass function as well as the distribution of exoplanets. Here we present the first results of an ongoing Spitzer-OGLE observational campaign carried out to that purpose towards the Galactic bulge. In particular we discuss the cases of OGLE-2014-BLG-0124 and OGLE-2014-BLG-0939, for which we present the first space-based measurements of the microlensing parallax respectively for a planetary and a single-lens microlensing event. For OGLE-2014-BLG-0124 we estimate a planet and host star mass of about 0.5 Jupiter mass and 0.7 Solar mass, respectively, with the planet separated from the host star by 3.1 AU in projection and the system lying at about 4.1 kpc from the Sun. For OGLE-2014-BLG-0939 the analysis strongly favors a lens in the Galactic disc of about 0.23 Solar mass at a distance of 3.1 kpc from the Sun.

Peter Capak ( IPAC/Caltech )

Co-authors: C. Steinhardt; D. Masters; J. Speagle; J. Silverman; O. Ilbert; H. McCracken; C. Scarlata; N. Scoville; D. Sanders
Title: Surveying the High Redshift Universe with Hyper-Suprime Cam, Spitzer, Euclid and WFIRST

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Abstract: I will present early results from the Spitzer large area survey with Hyper-Suprime-Cam (SPLASH), including measurements of the star forming main sequence, mass function, and clustering at 4 <z <6. This 2900h Spitzer survey is covering the 3.8 square degree Hyper-Suprime-Cam ultra-deep survey, which will reach ~27-28th magnitude AB from 0.4-1um. The combination of depth, area, and wavelength coverage is allowing us to measure how galaxies assemble their mass and how that interplays with large-scale structure and dark matter assembly. The Spitzer IRAC data is particularly important because it uniquely probes stellar mass at z >4. I will conclude by showing how Euclid and WFIRST studies of the high-redshift universe will be crippled if sufficient Spitzer data is not obtained before the end of its mission.

Daniel Dale ( University of Wyoming )

Title: Needs from other Facilities for Nearby Universe Science

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Abstract: Though WFIRST-AFTA would be a boon for extragalactic studies, multi-wavelength information beyond the observed near-infrared channel is key to a robust interpretation of any extragalactic survey. I will review particular additional channels and techniques that would enhance the galaxy and quasar legacy of WFIRST-AFTA.

William Dawson ( Lawrence Livermore National Lab )

Co-authors: Michael Schneider (LLNL)
Title: LSST - WFIRST Synergy: A New Domain of Blending Challenges

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Abstract: LSST and WFIRST will be complimentary in many ways, but exploiting the benefits of joint analysis will require careful analysis of blended objects as seen from the ground. LSST’s ugriz survey to a limiting magnitude of ~27.5 and WFIRST’s four-band infrared survey to a limiting magnitude of ~27 will enable 9 band photometric redshifts over an unprecedented combination of depth and area. The atmosphere blends galaxy images that appear to be distinct objects when viewed from space, leading to biased redshift estimates and galaxy shape measurements. To date the number density of galaxies has been small enough in shallow surveys to allow flagging and discarding blended images. Our preliminary estimates indicate that 30-50% of WFIRST galaxies will be blended in LSST, thus such a “flag and discard" approach is infeasible for WFIRST and LSST. We will discuss these findings and biases associated with photometry, photometric redshifts, and lensing that can be introduced due to blending when naive catalog cross-matching schemes are used. Finally we will outline a method of optimally combining the WFIRST and LSST surveys to minimize the effects of these biases.

Istvan Dekany ( Pontificia Universidad Catolica de Chile )

Co-authors: Dante Minniti; Marcio Catelan; Manuela Zoccali
Title: The VVV Survey: charting the Milky Way's bulge and disk

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Abstract: The VISTA Variables in the Via Lactea Survey (VVV) is an ongoing ESO public near-infrared variability survey of the Galactic bulge and an adjacent section of the Southern Galactic plane, observing 562 square degrees of the sky in ~100 epochs. The scientific potential lying in VVV data is immense and manifold, with the main objective of mapping the Galaxy in 3-D. Following a brief summary of the VVV time-domain observations and data analysis, I will focus on our latest results on the precision mapping of the Milky Way's hitherto unexplored components. Using RR Lyrae stars, among the oldest objects in our Galaxy, we unveil an ancient spheroidal component in the bulge, a relic from the earliest phases of its formation history. We chart the Great Dark Lane, a coherent large-scale extinction feature in front of the bulge. Using newly discovered, distant and highly reddened classical Cepheids, we trace the spiral arms in the far side of the Galactic disk. I will conclude by highlighting the latest progress and immediate prospects for the consummation of these studies upon VVV's completion, as well as synergies with other surveys.

Vandana Desai ( IPAC )

Co-authors: Harry Teplitz
Title: Synergies with Archival All-Sky IR Surveys

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Abstract: IR surveys reveal populations of important astronomical sources that are not detected or not recognized at shorter wavelengths (e.g. ULIRGs, SMGs). All-sky surveys also allow the discovery of extremely rare sources. Mining existing long-wavelength data for interesting objects will be vital to the success of survey science in the next generation of wide-area surveys. The resolution and unprecedented sensitivity of WFIRST (and Euclid, LSST) will in many cases entirely eliminate the need for dedicated follow-up imaging of sources identified at longer wavelengths. We will high-light advantages combining WFIRST and archival all-sky surveys, including analyses of the structure of distant galaxies, constraints on physical models provided by the SED, and the opportunity to extend time domain research using archival epochs (“pre-covery”).

Herve Dole ( Institut d'Astrophysique Spatiale (Univ Paris Sud & CNRS) )

Co-authors: Guery; Montier; Martinache; Nesvadba; Flores-Cacho; Altieri; Aghanim; Beelen; Bethermin; Chary; Douspis; Frye; Le Floc'h; Lagache; Pointecouteau; Puget
Title: New z>2 clusters unveiled by Planck, Herschel & Spitzer - prospects for WFIRST & Euclid

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Abstract: Searching for z >2 clusters/protoclusters is an active field in cosmology, and quite successfull using wide near-infrared surveys (e.g. Spitzer). We present a new approach by selecting highly star forming high-z cluster candidates over the whole sky using Planck, taking benefit of the redshifted far-infrared peak into the Planck submillimetre channels and a clean component separation (among which Galactic cirrus & CMB). About 200 hundreds were confirmed by a Herschel/SPIRE follow-up as significant overdensities of red sources, confirming their high-z spectral energy distribution and high star formation rates (typically 700 Msun/yr per SPIRE source, and >5000 Msun/yr for each structure). These overdensities could be protoclusters in their intense star formation phase. Few targets have spectroscopic redshift (in the NIR and mm) confirmations, all in the range 1.7-2.5, while photometric analysis indicates z >2 for all the Planck counterparts. The key here is that Spitzer data were obtained on 40 fields down to 1uJy 5sigma, and show unambiguous presence of galaxy overdensities compatible with z~2 (one of them being presented by C. Martinache et al) based on color analysis on 4 band photometry (J, K, 3.6 and 4.5um). These targetted Spitzer observations can serve as pilot project for the more extended data coming in the next decade from WFIRST and Euclid. This new window on the high-z (z >2) protocluster may yield powerful constraints on structure formation (e.g., SFR vs environnement at high-z, z >2 mass assembly in clusters, bias). Furthermore, these objects will allow to better quantify the prediction for clusters to be detected by WFIRST and Euclid. Finally, these clusters will help us extending the current search for high-z clusters, in nice complementarity with current selections in the near-infrared (dominated by stellar mass) and the millimeter (dominated by hot gas and SZ effect), using the far-infrared and submillimetre (dominated by star formation). My talk will review all these aspects.

Dennis Ebbets ( Ball Aerospace & Technologies Corp. )

Co-authors: Dennis Ebbets, Ball Aerospace; Ken Sembach, Space Telescope Science Institute; Susan Neff, NASA Goddard Space Flight Center
Title: Cosmic Origins Science enabled by the coronagraph instrument on NASA’s WFIRST-AFTA mission

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Abstract: The WFIRST-AFTA Science Definition Team has solicited community input for potential coronagraphic science investigations related to NASA’s Cosmic Origins and Physics of the Cosmos themes. In response, the Cosmic Origins Program Analysis Group, COPAG, formed Science Analysis Group #6 to identify investigations that may further enhance the science case for the instrument and the mission. While not a primary driver for the design, this study may provide helpful insight for resolution of trade studies and decisions about implementation choices. This presentation will cite several examples where interesting structures and phenomena are extremely close to much brighter central objects (in angular separation), and a coronagraphic instrument will make their study much easier. Examples include gravitationally-lensed images of very distant galaxies in Einstein rings, host galaxies of Quasars, AGN and jets, the intergalactic medium responsible for absorption lines in Quasar spectra, inner regions of protoplanetary disks, and matter ejected from Wolf Rayet stars, Luminous Blue Variables, cataclysmic variables and recurrent novae. We will describe capabilities of the AFTA coronagraph that would be beneficial to these investigations.

Tim Eifler ( JPL/Caltech )

Co-authors: Eric Huff (Ohio State University); Jason Rhodes (NASA-JPL/Caltech)
Title: Mitigation Strategies for WFIRST Weak Lensing Systematics

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Abstract: Weak gravitational lensing (WL) is one of the core probes of the WFIRST mission. In this talk we discuss high-precision forecasts of WFIRST WL systematics such as shear calibration, photo-z errors, baryonic effects, and intrinsic alignment. We present a PCA based technique that accounts for degeneracies between the systematics' parameters and compare results to the systematic-free case. We also discuss the latest updates on a new WL measurement technique, so-called kinematic WL (Huff et al 2013), which combines the spectroscopic and imaging capabilities of WFIRST. The method employs minimally resolved disk galaxy kinematics and the Tully-Fisher relation (TFR) to estimate both components of the shear while suppressing shape noise by an order of magnitude. Whereas shape noise is one of the major limitations for traditional WL experiments it ceases to be an important source of uncertainty in kinematic weak lensing. Furthermore, kinematic WL avoids the most important sources of astrophysical and observational systematic errors inherent in traditional weak lensing techniques: 1) the spectroscopic information removes photo-z errors inherent in imaging surveys, 2) the reduced number of galaxies allows for selecting high S/N candidates for which reliable shapes can be measured, 3) the spectroscopic information allows for measuring and mitigating the intrinsic alignment of galaxies.

Peter Eisenhardt ( JPL/Caltech )

Co-authors: Anthony Gonzalez; Mark Brodwin; Adam Stanford; Daniel Gettings; Daniel Stern
Title: Searching for Massive Distant Galaxy Clusters with WISE

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Abstract: Distant galaxy clusters probe the massive end of structure formation, provide substantial numbers of galaxies with a common lookback time, and highlight environmental effects on galaxy evolution. Infrared light is an excellent tracer of stellar mass (and hence of galaxy clusters), an effect enhanced by cosmological redshift. This property, combined with the rarity of massive galaxy clusters, makes wide field infrared surveys a potent tool to find them. The Massive Distant Clusters of WISE Survey (MaDCoWS) is using WISE to identify such clusters. Spectroscopic confirmation of 20 z~1 MaDCoWS clusters is in hand, and the first several Sunyaev-Zeldovich measurements obtain typical cluster masses in the range 2 to 6 E14 solar masses. SZ measurements of many more MaDCoWS clusters are underway. The increased depth from the additional coverages of the sky now being obtained by the reactivated NEOWISE survey offers the potential to identify large numbers of cluster candidates to z > 1.5.

Xiaohui Fan ( University of Arizona )

Title: WFIRST Performance and AGN/SMBH Science

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Abstract: I will discuss the WFIRST performance vs. science requirement in the context of AGN/quasar science, using specific AGN science cases, a number of which have been discussed in the SDT report, and the baseline HLS as examples. In particular, I will discuss WFIRST performance in the areas of: (1) imaging only AGN science, including searching for reionization-era quasars and quasar redshift survey based on photo-z; (2) AGN spectroscopic science, including identification of high-z AGNs, evolution of black hole mass function and AGN/galaxy co-evolution; and (3) high spatial resolution AGN science, including strong lenses and quasar host galaxies.

Harry Ferguson ( Space Telescope Science Institute )

Title: WFIRST Performance and Galaxy Science

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Abstract: This talk will address various kinds of investigations of galaxy evolution that could be carried out with WFIRST, either using data taken for the dark-energy investigations, or through guest-investigator programs. By providing high-resolution near-infrared imaging over very large areas, WFIRST will fill in a crucial gap in our ability to characterize galaxies at large look-back times. We will address WFIRST performance for making such measurements, both on its own and in concert with other facilities.

Ryan Foley ( University of Illinois )

Co-authors: Kaisey Mandel; Dan Scolnic
Title: Supernovae and the IFU

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Abstract: The intrinsic color of a Type Ia supernovae (SN Ia) is highly correlated with the velocity of the SN's ejecta. Because of a wide and skewed SN Ia intrinsic color distribution, the lack of velocity data biases intrinsic color estimates, and thus reddening and distance measurements. Luckily, the WFIRST-AFTA IFU can provide the necessary information for the WFIRST-AFTA SN sample if the IFU has sufficient resolution (R >~ 75) and the resulting spectra are high enough S/N (~20 per resolution element). These observations will both improve the distance precision of a SN Ia by >2 and reduce a potentially large systematic bias. I will suggest design criteria for the IFU (within, but stricter than, the current guidelines) and observing strategies to use the IFU efficiently and measure the most precise SN Ia distances.

Josh Frieman ( Fermi National Accelerator Laboratory )

Title: WFIRST/AFTA Dark Energy Science

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Scott Gaudi ( The Ohio State University )

Title: Recent Microlensing Results from the Ground and from Space

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Abstract: Microlensing is unique among planet detection methods in that it is potentially sensitive to analogs of all the solar system planets except Mercury, as well as to free floating planets. I review the landscape of current microlensing surveys for extrasolar planets, focusing on what these surveys have taught us about the frequency of cold terrestrial and giant planets, solar system analogs, and free-floating planets.

Gerry Gilmore ( Institute of Astronomy, Cambridge )

Title: Synergies with Gaia

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Abstract: Gaia is the ESA astrometric mission which is providing absolute astrometry and spectrophotometry for the complete sample of one billion stars brighter than magnitude ~20.5. In addition, radial velocities (and spectra) are being obtained for the complete sample of 60 million stars brighter than 15.3, while transients are being discovered and released in near real-time. Gaia started routine data-taking in July 2014, and will operate for at least 5 years, perhaps longer. I will provide an overview of Gaia's in-flight performance and our anticipated accuracies and data releases.

Michael Gladders ( The University of Chicago )

Title: Strong Lensing

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Abstract: Strong lensing from galaxy to cluster lens mass scales offers unique insight on both lenses and lensed sources. Progress in this field has been rapid in the past decade, in great part because of the advent of large digital sky surveys that have ramped up the total samples of known strong lenses from tens to hundreds. The Hubble Space Telescope, and a wealth of faint-object spectroscopy have also played core roles. The critical combination is wide field imaging (to define samples) coupled to high resolution multi-band imaging and spectroscopy (to characterize lenses system geometries). WFIRST-AFTA uniquely integrates this tripod of capabilities in a single observatory, ensuring that it will effectively revolutionize strong lensing studies across all relevant mass scales.

Tiffany Glassman ( Northrop Grumman Aerospace Systems )

Co-authors: Steve Warwick; Megan Novicki; Danny Smith; Suzi Casement
Title: Demonstration of Starshade Technologies

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Abstract: Over nearly a decade of development we have advanced a high-performance, technically feasible, external occulter concept, known as a starshade, from a new idea to a robust technology. The starshade has now been proposed for a variety of missions, pairing it with a space telescope to enable high-contrast imaging. I will discuss various demonstrations of starshade technology, focusing on two active areas of development that have been funded by NASA: a study of the control of stray light from the starshade edge and field testing of the optical performance of the starshade at ~1/100th scale. <P >Our recent tests of starlight-suppression performance in the field are part of an ongoing campaign – we have shown repeatable measured contrast better than 10^-8 using ~60 cm starshades. In the latest test we added a variety of starshade shapes designed to validate error budget predictions from optical modeling. We also added smaller (~30 cm) starshades to show the performance over a range of scales and Fresnel numbers. These measurements were made over a 50% spectral bandpass, using incoherent light sources (a white LED), and in challenging outdoor test environments. I will report on preliminary results from our latest test and the accomplishments of the campaign to date.

Andrew Gould ( Ohio State University )

Title: Non-Microlensing Astrophysics with WFIRST Microlensing Data

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Abstract: WFIRST microlensing observations (40,000 epochs covering 2.8 square degrees of the Galactic bulge) will automatically provide one of the most powerful astrometric and photometric data sets ever assembled. These will yield parallaxes that are 50--100 times more accurate than GAIA for the same stars, i.e., <3 uas for 40 million stars and <0.3 uas for 1 million stars, enabling precision spatial and kinematic maps. Combined photometric and astrometric data will enable asteroseismology of 1 million bulge stars at and above the red clump. At the opposite limit, these data will allow precision orbits of several thousand Kuiper Belt Objects that are fainter than the break at $R=26.5$, increasing the sample below $R=28$ by a factor of several hundred, and also enabling more than 1000 occultation measurements. I discuss these and many other non-microlensing applications, such as age measurements for millions of stars, mass measurements for black holes and neutron stars in wide binaries, and transits due to planets. The scientific return from non-microlensing applications of WFIRST microlensing data promises to rival those from microlensing itself.

Jenny Greene ( Princeton )

Title: PFS and Galaxy Evolution

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Carl Grillmair ( Spitzer Science Center )

Title: Exploring the Local Volume with WFIRST and LSST

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Abstract: WFIRST and the Large Synoptic Survey Telescope will be highly synergistic, particularly in the exploration of the remote regions of the Galactic halo and the intergalactic spaces within the Local Group. From enabling much better star/galaxy separation to measuring accurate distances to far flung RR Lyrae, WFIRST will facilitate much deeper, much more sensitive searches for ultra-faint dwarf galaxies, remote star clusters, tidal streams, and other Galactic formation debris. While these surveys will individually enable remarkable improvements in our exploration and characterization of the the Local Volume, it will be by leveraging these two datasets off one another that we will see the greatest gains in depth and sensitivity.

Sally Heap ( NASA/GSFC )


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Abstract: NASA’s Cosmic Origins (COR) Science Analysis Group #8 has been directed to “analyze how the WFIRST-AFTA archive is to be used and scope the data requirements necessary to conduct COR science investigations”. We are responding to this directive by following the example of the highly successful Sloan Digital Sky Survey (SDSS). To design the SDSS SkyServer, Szalay et al. (2000) first composed a set of 20 questions that they thought characterized the kinds of questions astronomers were likely to ask the SDSS archives. We have formulated a similar set of 20 questions for the WFIRST archives, drawing mainly from the "One-Page Science Ideas" appended to the WFIRST SDT Final Report (May 2013). The queries range from the simple to highly complex, but none more difficult than the SDSS questions. We will present these 20 questions at the conference. We hope that you will help improve these queries so that they can be used not only in the early design of the WFIRST archives but later, in stress tests of competitive designs. We also invite you to join us during the January 2015 AAS meeting when we expect to present the 20 questions to NASA.

Calen B. Henderson ( The Ohio State University Department of Astronomy )

Title: K2 and Spitzer: Paving the way for microlensing with WFIRST

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Abstract: The launch of WFIRST currently sits at least a decade away. In the interim, opportunities abound to prepare ourselves for the deluge of space-based exoplanet detections its microlensing component would provide. Spitzer, working in the IR, has been used to measure satellite parallax and constrain lens parameters. Furthermore, the proposed ninth field of the K2 mission offers the chance for a wide-field space-based microlensing survey toward the Galactic Bulge that, if carried out in concert with existing ground-based microlensing survey telescopes, would facilitate a significant augmentation of the total number of planet detections and mass measurements (not inferences) made with microlensing. Here we discuss the prospects of these missions for bridging the gap between current ground-based microlensing endeavors and WFIRST.

Christopher Hirata ( The Ohio State University )

Title: WFIRST high latitude survey

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Abstract: I will review the considerations behind the design of the WFIRST high Galactic latitude surveys. The capabilities of the currently envisioned surveys (depth, area, footprint location, resolution, dithering, and repeat observations) will be discussed. Finally, I will highlight areas for future trades as the mission design is refined.

Shirley Ho ( Carnegie Mellon University )

Title: Progress Report on the Dark Sector of the Universe

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Abstract: I will present progress of our current understanding of the Dark Sector of the Universe, utilizing recent results from CMB, BAO, SN, Lensing and other probes.

Philip Hopkins ( Caltech )

Co-authors: Paul Torrey (MIT-Caltech); Claude-Andre Faucher-Giguere (Northwestern)
Title: First Simulations of Black Hole Feeding with A Realistic ISM

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Abstract: Super-massive black holes (SMBHs) and AGN are of fundamental interest both in their own right and to cosmology and galaxy formation. However, the physics of angular momentum transport from galactic scales to an accretion disk is one of the outstanding problems in our understanding of the formation and evolution of SMBHs. New, multi-scale hydrodynamic simulations can probe these scales. On large scales, a mix of galaxy mergers and violent events, together with stochastic encounters between black holes and molecular clouds, drives fuel into galactic nuclei. Gravitational instabilities then drive inflow down into the viscous accretion disk. The last stage of this instability takes the form of a lopsided eccentric nuclear disk, which may also explain many properties of the putative AGN "torus". A wide range of observations also suggest there are changes to the dominant mechanisms driving inflow at certain characteristic luminosity thresholds, and these are closely related to a number of puzzles that make Seyferts not exactly analogous to quasars. I'll also discuss the implications of these processes for AGN host galaxies, the cosmological evolution of accretion, and "feedback" from black holes on their host galaxies.

Andrew Howard ( Univ. of Hawaii )

Co-authors: Benjamin J. Fulton
Title: High Precision Radial Velocity Observations To Support WFIRST

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Abstract: For spaced-based, high-contrast imaging missions, nearby stars with Doppler-discovered planets are attractive targets. The known orbits tell imaging missions where and when to observe, and the dynamically-determined masses provide important constraints for the interpretation of planetary spectra. Nearby stars with long histories of Doppler observations, but no detected planets, are also valuable. Quantifying the set of planet masses and orbits that could have been detected will enable more efficient planet discovery and characterization. We recently considered the historic Doppler measurements from Lick and Keck Observatories by the California Planet Survey, focusing on stars that are likely targets for three space-based planet imaging mission concepts -- WFIRST, Exo-C, and Exo-S. The Doppler planet search targets are primarily main sequence stars with spectral type F8 and later, with observations spanning 1987-2014 and sensitivity to orbital periods comparable to Saturn's. We identified 76 stars with Doppler measurements from the prospective mission target lists. We developed an automated planet search and a methodology to estimate the completeness of Doppler measurements to planets using injection and recovery tests. We applied this computational machinery to the Lick and Keck data and computed planet detection limits for each star as a function of planet minimum mass and semi-major axis. For typical stars in the survey, the Lick and Keck measurements are sensitive to approximately Saturn-mass planets inside of 1 AU, Jupiter-mass planets inside of ~3 AU, and declining sensitivity out to ~10 AU. For the best Doppler targets, we are sensitive to approximately Neptune-mass planets in 3 AU orbits. Using an idealized model of Doppler survey completeness, we forecast the precision of future surveys of non-ideal Doppler targets that are likely targets of imaging missions. We conclude with recommendations for maximizing the efficiency and planet yield of space-based imaging missions by pre-observing target stars using Doppler techniques. Absent a dedicated search, most imaging mission targets will have not been probed by Doppler spectroscopy, but such measurements could yield important constraints on giant planets in several AU orbits.

Mike Hudson ( University of Waterloo )

Title: Canadian Participation in WFIRST

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Abstract: The 2010 Canadian Long-Range Plan ranked participation in a wide-field Dark Energy satellite mission as the top space-based priority. Canada has strong scientific communities in the scientific areas of WFIRST: Dark Energy (particularly weak gravitational lensing and large-scale structure) and Exoplanets. Also, Canada has a long tradition in wide-field optical and near-IR imaging, primarily via CFHT and large-scale surveys such as the CFHT Legacy Survey. For these reasons, the Canadian Space Agency supports the author's membership on the WFIRST Science Definition Team. I will discuss the landscape of wide-field astronomy in Canada and the potential opportunities for a Canadian scientific and instrumentation contributions to WFIRST.

Remy Indebetouw ( University of Virginia )

Title: Interstellar extinction law

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Akio K Inoue ( Osaka Sangyo University )

Co-authors: Toru Yamada (Tohoku/JAXA*); Ikuru Iwata (NAOJ); Giovanni Fazio (SAO/CfA); Denis Burgarella (LAM); Marcin Sawicki (St.Mary's); and WISH Team
Title: WISH: Wide-field Imaging Surveyor for High-redshift: Complementary mission with WFIRST

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Abstract: We would like to present WISH: Wide-field Imaging Surveyor for High-redshift, which is a Japanese-lead concept for future JAXA/ISAS space science mission in early 2020's being developed with potential international partner institutes. The primary science goal of WISH is to conduct deep and wide imaging survey at the NIR wavelength at 1-5 micron to investigate the earliest galaxy formation at redshift z=7-20. The WISH concept has been developed under JAXA/ISAS WISH Working Group since 2008.It has 1.5m-diameter primary mirror and very wide-field imager with 850 arcmin^2 field of view with 0.155 arcsec pixel scale.The key feature is the Ultra Deep Survey with the depth of 28 AB magnitude covering 100deg^2 area which is combined with the wider shallow and narrower deepest surveys. This mission concept independently developed in Japan is very much complementary with WFIRST both in science cases and in wavelength coverage. As the synergy between Hubble and Spitzer has produced tremendous science outputs, it would be very much desirable WFIRST and WISH will realize great synergy in deep wide-field observation in 2020's. Please visit http://wishmission.org/jp/index.html for more detail about WISH.

Bhuvnesh Jain ( University of Pennsylvania )

Title: Dark Energy context including modified gravity: Beyond LambdaCDM

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Abstract: Cosmic acceleration is attributed to a form of dark energy or to deviations in gravity from Einstein’s general relativity. It has recently been appreciated that the new fields that are generically part of such theories have several interesting observational consequences. These span stellar and galactic phenomena to large-scale structure. Using analyses of current observations I will discuss the prospects for surveys in the WFIRST and LSST era.

David Jewitt ( UCLA )

Title: Solar System Science

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Abstract: The solar system is the only planetary system we can study in close detail, offering many opportunities for science and raising many important questions. In this talk, I will provide a broad overview of recent results obtained by planetary astronomers, focusing on big-picture issues regarding the formation conditions and subsequent evolutionary processes. The central role of sky surveys will be emphasized.

Christian Johnson ( Harvard-Smithsonian Center for Astrophysics )

Title: Exploring Galactic Bulge Stellar Populations with WFIRST

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Abstract: Ground-based photometric and spectroscopic studies have revealed a great deal about the chemodynamical composition of the Galactic bulge/bar system. For example, the recently discovered double red clump along various bulge sight lines has been shown to trace out an X-shaped structure, and results from kinematic surveys such as BRAVA and ARGOS find that the bulge rotates cylindrically with little evidence of a significant "classical" bulge component. Chemical composition measurements indicate that a large fraction of bulge stars are similar in composition to the local thick disk, and there is some evidence that the bulge may host two or more distinct populations. Similarly, the (largely unexplored) bulge/inner Galaxy globular cluster population appears more complex than previously thought. Several clusters contain double horizontal branches or very blue horizontal branches, and unusual clusters such as Terzan 5 may even be remant building blocks of the inner Galaxy. However, strong differential reddening and complex line-of-sight population mixing currently hamper our ability to interpret these results. Space-based wide-field surveys such as WFIRST may provide the capabilities necessary for isolating and further studying the various bulge field and globular cluster populations.

Jeremy Kasdin ( Princeton University), Neil Zimmerman (Princeton University )

Title: Opportunities and Challenges with Coronagraphy on WFIRST/AFTA

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Abstract: The availability of the AFTA for WFIRST has also made available the opportunity for a high-contrast, exoplanet imaging coronagraph. This will be the first extremely high-contrast coronagraph of its kind, and the first in space combined with large format deformable mirrors for wavefront control. During Fall 2013 a study was conducted to select the combination of coronagraphs for the baseline instrument design, culminating with the choice of a Hybrid Lyot and Shaped Pupil coronagraph. Since then, manufacture and testing has begun at the High Contrast Imaging Lab at JPL. In this talk I'll describe the challenges associated with coronagraph design and optimization for the AFTA telescope, in particular with achieving sufficiently small inner working angle and contrast, and the potential science being enabled.

Mansi Kasliwal ( Carnegie Observatories )

Title: Time Domain Science with WFIRST

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Abstract: I will begin with presenting puzzling infrared transient discoveries from SPIRITS (SPitzer InfraRed Intensive Transients Survey). SPIRITS is a systematic exploration of 190 galaxies within 20 Mpc to a depth of 20 mag with Spitzer/IRAC. Thus far, SPIRITS has discovered over 40 infrared transients and over 1200 infrared variables. Some have no optical counterparts whatsoever (in deep ground-based and HST/DD imaging). I will conclude with thoughts on exciting time domain science opportunities with WFIRST.

Lisa Kewley ( Australian National University )

Title: The Contemporary Universe in the WFIRST Era

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Abstract: I will discuss how WFIRST data will deepen our understanding of the evolution of galaxies, particularly between 0<z<2. I will present our current knowledge of galaxy evolution, as obtained from rest-frame optical and UV spectroscopy. I will describe our current understanding of the chemical and star-formation history of galaxies to z=3.5, as well as new work focusing on the ISM and star-forming conditions across 0<z<3.5. I will describe potential and planned surveys with WFIRST, and how these surveys can help us gain a more complete understanding of galaxy evolution in this redshift range.

Karen Kinemuchi ( Apache Point Observatory/NMSU )

Title: Variable stars as Galactic probes

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Abstract: With the advent of many ground and space-based surveys, the study of variable stars have expanded tremendously. Not only are we discovering new and unique properties to the variable stars, but we are revisiting their utility to study and probe the Milky Way and Local Group galaxies. Variable stars found within the instability strip, such as Cepheids and RR Lyraes, have traditionally been used as distance indicators, and are easily identified in photometric surveys with time-series data collection. With the coverage of the WFIRST spacecraft, finding new dwarf galaxies and tidal debris streams with a variable star population can help map Galactic halo structures. I will discuss how RR Lyrae variable stars can aid in the WFIRST Galactic mission goals.

Ashley King ( University of Cambridge) Laurent Pueyo (STScI) Steve Rodney (Johns Hopkins University )

Title: Astronomy Landscape in Twenties

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Abstract: We will look ahead to imagine the landscape of astronomy in the 2020's, highlighting prospects for exciting questions, new capabilities, and changes in the way astronomy will be done a decade from now. Ashley will discuss compact accretion, as well as feedback from these objects on all scales (pc to Mpc). Steve will explore transients and supernovae in the early universe. And Laurent will discuss how upcoming facilities will open yet unexplored high angular resolution and deep contrast windows into circumstellar environments.

J. Davy Kirkpatrick ( IPAC/Caltech )

Title: A Continuation of WISE Brown Dwarf Science into the WFIRST-AFTA Era

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Abstract: The WISE mission is ideally suited for the discovery of cold brown dwarfs because such objects have their peak emission in the WISE W2 bandpass (~5 microns). The shorter wavelength bands of WFIRST-AFTA will probe to deep limits (Vega mags at J and H of ~25-26), and its wide-field imaging (~2400 sq deg) allows a sizable volume of space to be surveyed for brown dwarfs down to at least 300K and in a wavelength regime independent of WISE. Data from this wide-field survey can also map out the extent of the “subdwarf gap” first detected by follow-up of WISE sources. This gap is believed to be the T_eff void created between the populations of low-mass main sequence stars and ever-cooling brown dwarfs at very old ages, and determining the extent and depth of the void would be a powerful check of theoretical cooling models. WFIRST-AFTA allows another independent check of WISE brown dwarf selections - and a check of its own color selections - through the grism spectroscopic component of the wide-field survey, whereby the unique SEDs of brown dwarfs at H-band can be identified directly. Finally, the opportunity to apply for General Observer time on WFIRST-AFTA means that multi-epoch imaging of random fields will be possible. These multiple epochs and the astrometric precision of WFIRST-AFTA will allow a proper motion search for cold, nearby objects with smaller motions that those obtainable with WISE (including the use of data from the continuing NEOWISE survey), albeit over much smaller swaths of sky.

Robert Kirshner ( Harvard University )

Title: Type Ia Supernovae

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Elisabeth Krause ( Stanford )

Title: Combining Probes of Large-Scale Structure in the Precision Cosmology Era

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Abstract: WFIRST and other upcoming large-scale structure surveys aim to determine the composition of the Universe and the nature of dark energy by mapping the spatial distribution and shapes of hundreds of millions of galaxies. These data sets will enable precision measurements of various observables of large-scale structure, such as weak lensing, galaxy clustering, and the abundance of galaxy clusters. These observables probe different aspects of cosmic structure formation, and combining them improves constraints on cosmology significantly. <br > <br >In this talk I will introduce the analysis concepts for the joint analysis of probes of large-scale structure currently under development for CosmoLike, a fast and self-consistent LSS likelihood analysis package. In particular, I will discuss cross-correlations of observables, and modeling and mitigation of systematic uncertainties affecting multiple probes in the context of the WFIRST mission design. I will also give a brief outlook on synergies between WFIRST's measurements and other surveys.

Hal Levison ( Southwest Research Institute )

Title: The Formation of Planets from the Direct Accretion of Pebbles

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Abstract: A radical new scenario has recently been suggested for the formation of giant planet cores that reports to solve this long-standing problem. This scenario, known as pebble accretion, envisions: 1) Planetesimals form directly from millimeter- to meter-sized objects (the pebbles) that are concentrated by hydrodynamic forces and then gravitationally collapse to form 100 - 1000 km objects (Cuzzi+ 2008, AJ 687, 1432; Johansen+ 2007, Nature 448, 1022). 2) These planetesimals quickly sweep up the remaining pebbles because their capture cross sections are significantly enhanced by aerodynamic drag (Lambrechts & Johansen 2012, A&A 544, A32; Ormel & Klahr (2010) A&A Volume 520, id.A43). Calculations show that a single 1000 km object embedded in a swarm of pebbles can grow to ~10 Earth-masses in less than 10,000 years. However, recent full-scale simulations of core formation with this process have failed to reproduce the giant planets in the Solar System (Kretke & Levison 2014, AJ, in press). I will discuss a new modification to the basic pebble accretion picture that appears to solve this problem and apply these new ideas to the terrestrial planet region.

P. Douglas Lisman ( JPL )

Title: Mission, Telescope and Starshade Requirements for L2 Operation

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Abstract: Starshades enable the direct imaging of Earth-sized exoplanets by non-specialized telescopes. Starlight is suppressed before entering the telescope, so no wavefront correction is required. WFIRST/AFTA modification to operate with a starshade can be limited by integrating the starshade instrumentation into the coronagraph instrument. If WFIRST/AFTA is operating at Earth-Sun L2, a separate starshade mission can be launched to rendezvous with WFIRST/AFTA after primary mission objectives are complete. This presentation details such a starshade mission concept and requirements on the telescope and starshade.

Sangeeta Malhotra ( Arizona State University )

Co-authors: James Rhoads
Title: Cosmic Dawn with deep slitless spectroscopy from WFIRST-AFTA.

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Abstract: WFIRST-AFTA can be used to find galaxies at the epoch of reionization using deep slitless spectroscopy. The wide field will afford unprecedented statistics to probe the epoch, speed, and inhomogenieties in reionization. A reasonably deep field with slitless spectroscopy mode would yield spectra of 1000 lyman-break-galaxies per square-degree per unit redshift, yielding enough statistics to probe clustering of ionizing sources, evolution of Lyman-alpha fractions and toplogy of reionization. Imaging data from the supernova survey alone would yield about 200,000 galaxies at z~8 and 9 as a "byproduct". Deep slitless spectroscopy data from the HST Faint Infrared Grism Survey (FIGS) will be extremely useful to plan and inform WFIRST deep fields.

Maria Messineo ( MPIfR (Max Planck Institute for Radioastronomy) )

Co-authors: Messineo Maria; Menten Karl M.; Figer Donald F.; Davies Ben; Clark J. Simon; Ivanov Valentin D.; Kudritzki Rolf-Peter; Rich R. Michael; MacKenty John W.; Trombley Christine
Title: Unveiling massive stars in giant molecular clouds.

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Abstract: Massive stars are useful indicators of distance for distant galaxies, are essential ingredients for the chemical enrichment of the interstellar medium, and produce the most energetic emission of the universe. In our Galaxy massive stars can be studied in great detail, but their detection and census suffer from our location on the Disk and heavy dust obscuration. By combining 2MASS, GLIMPSE, and WISE data, we have unveiled a dozen massive O-type stars, a candidate luminous blue variable, and several red supergiant stars in the GMC G23.3-0.3. This GMC is rich in HII regions and SNRs, including SNR W41 (Messineo et al. 2014 arXiv1408.3558). Future availability of deep photometric measurements (e.g. from LSST and WFIRST), will allow to probe the rich population of fainter blue stars (for example, associated with clusters of bright obscured red supergiants). These red supergiants and candidate luminous blue variable (there are only about 20 known in the Milky Way) could be considered as targets for the coronagraph on board of WFIRST for studies of binarity and circumstellar nebulae.

Michael McElwain ( NASA Goddard )

Title: The Promise and the Challenges of Multiplex Spectroscopy for Exoplanet Science

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Abstract: The key goal of the AFTA-C instrument is to discover and characterize exoplanets with direct imaging. Regardless of the technique chosen to suppress the starlight and enabling detection of the exoplanet, the ideal science camera would be capable of both high-resolution imaging and spectroscopy. Current ground-based telescopes equipped with adaptive optics and integral field spectrographs have recently demonstrated spectral characterization of exoplanets with direct imaging, displaying great promise for applications to the AFTA-C. However, current IFS cameras operate in a contrast regime orders of magnitude from what is expected on AFTA-C. I will review the techniques for achieving multiplex spectroscopy and the technical challenges that need to be addressed to further improve their high contrast imaging performance.

Simona Mei ( Observatory of Paris )

Co-authors: et al.
Title: Galaxy Cluster Science with Future Wide-Field Infrared Surveys: What we can say from Hubble, Spitzer and ground-based IFU observations

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Abstract: Galaxy clusters and proto-clusters are unique environments for galaxy formation and cosmological studies. The next generation of wide-field infrared space missions, such as WFIRST and Euclid, will permit us to detect and characterize thousands of these massive objects, through both imaging and grism spectroscopy, and to examine their galaxy proprieties with powerful integral field units. As an example of this promising science, we will present our new high redshift (z >1.5) cluster and protocluster detections in the HST CDF-S, CANDELS and SSDF fields using deep observations with Spitzer, the HST/WFC3 grism spectroscopy (Mei et al. 2014; Licitra et al., in preparation) and VLT/KMOS IFU spectroscopy (Mei et al., in preparation; Licitra et al., in preparation). We will discuss the implications of our results in terms of galaxy evolution and predictions for future wide-field infrared surveys based on mock Euclid galaxy catalogs simulated by our team (Licitra et al., in preparation; Ascaso et al., in preparation).

Margaret Meixner ( STScI )

Title: Infrared Surveys of the Magellanic Clouds: A WFIRST addition

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Abstract: The Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) are the Milky Way’s well studied, low-metallacity, gas-rich, neighboring galaxies. They have offered outstanding opportunities to investigate well resolved stellar populations and the interstellar medium with the statistics you can only get from entire galaxies. The LMC and SMC are interacting and this interaction includes the Magellanic Stream that encircles half the sky. In this talk I will give a brief overview of prior surveys of the LMC and SMC including: 2MASS, DENIS, IRSF, SAGE, HERITAGE, Akari, OGLE, MACHO, and VMC. These surveys have included photometry, spectroscopy and variability measurements. The near-infrared wavelengths of WFIRST are well suited to studies of stellar populations from the birth-line to their evolved dying states and variability is of particular interest. I will highlight recent work from the near-IR surveys to give some context on what we can learn. The wide-field capability of WFIRST and its remarkable sensitivity will allow measurements over a larger area of the Magellanic Clouds enabling investigations of the entire system.

Brian Metzger ( Columbia University )

Title: Discovering the Electromagnetic Counterparts of Binary Neutron Star Mergers with WFIRST

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Abstract: The merger of binary neutron stars are the most promising sources for the direction detection of gravitational waves with Advanced LIGO and Virgo starting in the next few years. Maximizing the scientific potential of these discoveries will require identifying a coincident electromagnetic counterpart. Among the most promising counterparts is a supernova-like transient (a `kilonova') powered by the radioactive decay of heavy r-process nuclei synthesized in the merger ejecta. Recent calculations show that the optical opacity of r-process matter is orders of magnitude higher than in normal supernovae, causing the kilonova emission to peak at near-infrared wavelengths on a timescale of several days. I will describe how the unique sensitivity and wide field capabilities of WFIRST could enable the discovery and characterization of binary NS mergers in the era of Advanced LIGO/Virgo. Such a discovery will also help identify the unknown origin of the heaviest elements in the universe.

Caroline Morley ( UC Santa Cruz )

Co-authors: Mark Marley; Nikole Lewis; Roxana Lupu; Jonathan Fortney; Michael Line; Kerri Cahoy
Title: Reflected Light from Giant Exoplanets

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Abstract: A space-based coronagraph such as the one slated to fly on the WFIRST/AFTA mission will for the first time reveal light from planets much like the ones in our own solar system. These planets, like the solar system gas giants, will likely have diverse compositions, a variety of clouds, absorption from molecules like methane, and photochemical hazes. It is important to understand, before the instrument flies and observations are made, what we can expect to learn from these planets’ reflected light spectra. Previous studies in the solar system have used multiple methane absorption features of varying strengths in visible light to disentangle the competing effects of molecular abundance and the continuum opacity from clouds and hazes. Here, we present models of specific planets discovered by radial velocity that will be some of the first and best targets for a coronagraphic space mission. We show how the signal-to-noise and spectral resolution of the predicted observations will affect how well we can determine a number of different planet properties, including atmospheric metallicity, cloud thickness, internal heat flux, and surface gravity. We also show some preliminary results from a new retrieval model, which will be used to determine the methane abundance and cloud properties using a Bayesian approach. This is the first time this technique has been applied to reflected light spectra, and we will demonstrate the results for spectra of solar system giants and model planets degraded to the lower spectral resolution and signal-to-noise of exoplanet observations.

Eric Murphy ( California Institute of Technology )

Co-authors: The VLASS Survey Science Group (SSG)
Title: The Jansky Very Large Array Sky Survey (VLASS)

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Abstract: We will soon begin to see a next generation of space-based infrared surveys coming online, including the Decadal Survey's top priority, a wide-field infrared survey telescope (WFIRST). In light of this, and planned synoptic surveys using future ground-based facilities such as LSST, there has been significant interest in employing the VLA to conduct a new, wide-area centimeter wavelength sky surveys in support of these other multi-wavelength efforts. This has lead to the development of the Jansky VLA Sky Survey (VLASS) initiative, in which more than 200 multi-wavelength astronomers have worked to develop a survey definition that comprises a cohesive and aggressive science program that will benefit the entire astronomical community, deliver unique forefront scientific discovery, and keep its legacy value well into the SKA-era. The proposed VLASS is a modern, tiered (“wedding-cake”) survey, structured to combine comprehensive all sky coverage (“ALL-SKY”) with sequentially deeper coverage (“WIDE” and “DEEP”) in carefully identified parts of the sky, including the Galactic plane. A key aspect of VLASS is that this is all done while additionally informing time domain studies. In my talk I will describe the recently proposed VLASS along with the key science questions it will address. In doing so, I will put VLASS in perspective with a number of other SKA pathfinder surveys that will soon be coming online, as well as the potential reference surveys being planned for the SKA itself.

Jeffrey Newman ( U. Pittsburgh )

Co-authors: Samuel Schmidt, U.C. Davis; Carlos Cunha, SLAC; Saul Perlmutter, LBL; Chris Hirata, OSU
Title: Photometric Redshifts for WFIRST and LSST: Challenges and Synergies

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Abstract: Both LSST and WFIRST face significant challenges in training and calibrating photometric redshifts. The greatest of these is the fact that spectroscopic samples obtained to date are highly systematically incomplete even at significantly shallower depths than future surveys will attain. In this talk I will highlight some of the challenges that will need to be addressed in developing combined LSST-WFIRST photo-z's, as well as the benefits to each project which will come from combined analyses. Depending on its final design and the survey strategy, the WFIRST IFU may play an important role in addressing the incompleteness in current spectroscopic samples by providing well-calibrated spectra with broad spectral coverage into the IR for tens of thousands of objects down to the LSST and WFIRST survey depths.

Pascal Oesch ( Yale University )

Title: Probing the Dawn of Galaxies: Lessons from Ultra-Deep Observations with Hubble and Spitzer

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Abstract: The last few years have seen a remarkable revolution of galaxy observations within the epoch of reionization. Thanks to the high sensitivity of the WFC3/IR camera on the Hubble Space Telescope (HST) the frontier of galaxies has now been pushed out to z~9-12, only ~450 Myr from the Big Bang. However, until recently only a small number of intrinsically very faint galaxies could be identified at these redshifts based on extremely deep WFC3/IR data over the HUDF, in addition to the CLASH cluster survey. This changed with our recent analysis of the wider area CANDELS survey data, from which we identified a sample of six surprisingly bright Lyman break galaxy candidates at z~9-10. These sources are a factor ~10-20x brighter than any previous candidate at these redshifts. Additionally, four of these sources are even significantly detected with Spitzer/IRAC which probes their rest-frame optical light. This indicates that these sources already had a stellar mass of ~10^9 Msol at a cosmic time of only 500 Myr. While the SFRD of galaxies with SFR >0.7 Msol/yr is found to decrease rapidly from z~8 to z~10, the discovery of these luminous sources has very promising implications for the detection of such early galaxies with the upcoming wide field NIR imaging capability of WFIRST.

Nikhil Padmanabhan ( Yale University )

Title: Dark Energy with Galaxy Surveys : Prospects and Challenges

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Abstract: Large scale structure measures, including baryon acoustic oscillations and redshift space distortions, are some of the most powerful probes of dark energy. I will summarize the current status of these measurements. I will then discuss the ambitions of the next generations of surveys and the challenges on the road ahead.

Matthew Penny ( Ohio State University )

Title: The planets at the extremes of microlensing's sensitivity

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Abstract: WFIRST will be the most powerful planetary microlensing survey conducted and will detect thousands of exoplanets beyond the snowline. In this talk I will discuss the limits of WFIRST's sensitivity, from Earths in and around the habitable zone, through cold moon-mass objects to Pluto-mass free-floating planets.

Ilya Poberezhskiy ( JPL / Caltech )

Title: WFIRST Coronagraph Technology Development: Recent Testbed Results and Plan to TRL5

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Abstract: WFIRST/AFTA mission study includes the first high-contrast stellar coronagraph in space. After a rigorous downselect process, a primary design called the Occulting Mask Coronagraph that combines two operational modes, Shaped Pupil and Hybrid Lyot, was selected by NASA. An objective of maturing this coronagraph to technology readiness level (TRL) 5 by 9/30/2016 was set, with 9 key milestones defined to track the technology development progress along the way. In this presentation, I will describe our technology development plan and milestones, as well as the results achieved in 2014, including
  • Fabrication and characterization of WFIRST/AFTA coronagraph pupil plane and focal plane masks designed to work with the obscured 2.4 meter telescope,
  • Experimental starlight suppression results from the coronagraph testbeds,
  • Progress in the development of the low-order wavefront sensing and control subsystem.

  • Abhishek Prakash ( University of Pittsburgh )

    Co-authors: Jeffrey Newman - University of Pittsburgh; The SDSS-IV/ eBOSS collaboration
    Title: New technique of Selecting Luminous Red Galaxies at High Redshifts combining Optical and Infrared photometry

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    Abstract: Luminous red galaxies (LRGs) are the most massive galaxies in nearby universe of z < 1.0 which appear to be dominated by old stellar populations. These galaxies are believed to be undergoing passive evolution. Mostly ellipticals, they are associated with massive dark matter halos and hence cluster very strongly. Their strong clustering combined with their intrinsic brightness makes them an excellent tracer of the Universe on largest scale. LRGs at z < 0.6 can be selected efficiently using optical photometry, but at z >0.6 this becomes increasingly difficult. In this talk, we underline the critical role played by WISE in helping us develop a new technique now being applied to select LRGs at redshifts 0.6 < z < 1 utilizing optical and WISE (infrared) photometry in combination. Old stellar populations exhibit a global maximum in their SED at a wavelength of 1.6 μm, commonly referred to as the '1.6 μm bump'. Since LRGs possess very few young stars, this feature generally dominates their overall spectral energy distribution. The lowest- wavelength channel in WISE is centered at 3.4 μm, causing LRGs that are at z~1 to be extremely bright in this band compared to the optical. As a result, the r-W1 vs. r-i color-color diagram (where W1 is the 3.4 μm WISE AB magnitude) provides an efficient tool for selecting high-redshift LRGs while avoiding stars. We also present new results from efforts to optimize the color cut used to select LRGs, yielding samples with a very low stellar contamination rate, but a high fraction of galaxies that are both at z >0.6 and intrinsically red in color. Studying their properties and distribution can also help us determine the mechanisms by which these rare objects form and variety of other exciting science. We have tested this method using photometric redshifts and spectroscopic redshifts in the COSMOS field and DEEP2 fields respectively. LRGs selected with this method will be the targets for future-generation surveys such as DESI and undergoing surveys like, SEQUELS BOSS ancillary survey and SDSS-IV/eBOSS which aim at high precision measurement of BAO.

    Alessandro Rettura ( IPAC/Caltech )

    Co-authors: Martinez-Manso, J.; Stern, D.; Mei, S.; Ashby, M. L. N.; Brodwin, M.; Gettings, D.; Gonzalez, A. H.; Stanford, S. A.; Bartlett, J. G.; Rosati, P.
    Title: The search for the most distant clusters of galaxies with Spitzer: synergies with WFIRST.

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    Abstract: We present results from the ongoing high redshift cluster search in the 94 deg2 Spitzer SPT Deep Field (SSDF) survey. We have identified 279 galaxy cluster candidates at z >1.3 using a simple three filter algorithm based on Spitzer/IRAC mid-infrared data combined with shallow wide-field optical data. We select distant cluster candidates adopting a significance overdensity threshold which is shown to result in an 80% pure cluster sample. The uniqueness of the SSDF survey resides not just in its area, one of the largest contiguous extragalactic field observed with Spitzer, but also in its deep, multi-wavelength coverage by the South Pole Telescope (SPTpol) that will allow us to measure cluster masses for the majority of our sample. Furthermore we consider this method applied on SSDF as the pilot study to be extended to the entire Spitzer/IRAC data available in the archive, providing the ultimate catalog of high-redshifts MIR-selected clusters. The upcoming large-scale survey of WFIRST has distant cluster studies as key scientific goal. Spitzer cluster surveys will provide exciting high-redshift targets for WFIRST, enabling unique, exciting, synergic, multi-wavelength studies of the Spitzer-selected sample, as well as a training set to identify additional high-redshift clusters outside of the Spitzer footprint.

    Michael Rich ( UCLA )

    Co-authors: Ortwin Gerhard; Christian Johnson; Will Clarkson
    Title: Exploring the dynamics and subpopulations of the bulge using WFIRST

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    Abstract: The Galactic bulge has an X-shaped structure on the minor axis and appears to have a "long bar" and nuclear disk/nucleus within the central 100 pc, along with possible kinematic substructure. There is a commingling of multiple populations of different ages and metallicities in the nuclear region, and of the Sagittarius dwarf and the old bulge, outside of ~500 pc. We are developing a series of fields that will discriminate and refine the bulge dynamical model; these "fields of interest" - FOI's will be selected from a bulge dynamical model that presently fits some of the observations, and the FOI's will be observed with WFIRST and used to refine and test the model. The Blanco DECam bulge survey, an LSST pathfinder, has completed its Southern bulge campaign in six SDSS colors, and will help to select additional bulge FOIs for WFIRST. We will also discuss how the WFIRST dataset will be of great legacy value in the matching and population classification of the rich array of UV/X-ray etc. sources in the bulge.

    Jane Rigby ( NASA Goddard Space Flight Center )

    Co-authors: Mike Gladders; Keren Sharon; Matt Bayliss; Eva Wuyts
    Title: Diagnostic spectroscopy of lensed galaxies

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    Abstract: High magnification from gravitational lensing transforms our view of distant galaxies, from faint objects that are marginally resolved by current telescopes, into spatially resolved bright objects for which current telescopes can obtain high signal-to-noise spectroscopy. Such diagnostic spectroscopy probes the stellar populations and physical conditions inside star-forming galaxies at redshifts of 1 <z <3, the epoch when most of the Universe's stars were formed. I will summarize results from our comprehensive program of spectroscopy with Keck, Magellan, and Hubble to characterize star formation in highly--magnified lensed galaxies. A highlight that is particularly relevant for WFIRST is constraining the ages of individual star-forming regions at z=1.7 through faint He I and He II emission lines detected by the HST WFC3 G141 grism. I will close with potential paths forward for studying lensed galaxies with JWST and WFIRST.

    Aki Roberge ( NASA GSFC )

    Co-authors: S. Seager (MIT); the EXO-S Science and Technology Definition Team; and the EXO-S Design Team
    Title: Scientific Opportunities with a Starshade Working With a 2.4 m Telescope at L2

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    Abstract: A starshade paired with an existing 2.4 m telescope offers scientific opportunities in direct observations of exoplanets that are complementary to those offered by the internal coronagraphs. Most excitingly, since the inner working angle is decoupled from the telescope aperture, a starshade can provide access to the habitable zones of some nearby stars, possibly allowing direct imaging and low-resolution spectroscopy of Earth-analog exoplanets. In this talk, I will summarize a potential starshade design for a 2.4 m telescope, briefly discuss the changes to the WFIRST mission that would be needed for it to be “starshade-ready” (as well as some that are desirable but not required), and give preliminary estimates of the scientific capabilities.

    Brant Robertson ( University of Arizona )

    Title: WFIRST/AFTA Surveys of the Epoch of Reionization

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    Abstract: The Epoch of Reionization (EoR) that marks the phase transition from a mostly neutral to an ionized intergalactic medium likely occurred in the first billion years of cosmic history, at redshifts z >~6. <br > <br >Infrared surveys provide a powerful probe of this era, as rest-frame UV drop-out selections can efficiently identify distant galaxies that served as the most abundant ionizing sources at these times. Previous Hubble Space Telescope surveys, including our Ultra Deep Field 2012 program, have provided a first measure of the abundance and luminosity of star-forming galaxies during the critical time at redshifts 6 <z <8 when the EoR was completing. The HST samples are meager and our inferences still uncertain, but WFIRST/AFTA can revolutionize our knowledge of the EoR by discovering enormous samples of high-redshift galaxies, measuring their abundance, and importantly their spatial clustering. In contrast to the James Webb Space Telescope that is optimized for observations at higher-redshifts (z >8), WFIRST/AFTA is an ideal tool for studying the end of Reionization. This talk will provide an overview of what WFIRST/AFTA will tell us about the EoR, and how its operations can be usefully optimized to provide the largest return for EoR science.

    Huub Rottgering ( Leiden Observatory )

    Title: The Synergy of Combining the Radio and WFIRST Sky.

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    Abstract: For the next decade a very large fraction of the radio sky will be deeply surveyed at the lowest frequencies accessible from the ground up to the GHz regime. We will give an overview of the facilities that are currently being commissioned or built and sketch the plans for the SKA surveys. Combining these surveys with results from WFIRST, many astrophysical science issues can be addressed. These include the accretion history of massive black holes, the formation and evolution of clusters, the star formation history of galaxies and precision determination of cosmological parameters. These science cases will be briefly reviewed together with some recent results from the new pan-European telescope LOFAR.

    Kevin Schlaufman ( MIT )

    Co-authors: Andrew R. Casey
    Title: An Infrared Search for the First Stars

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    Abstract: The bulge is thought to be the most likely location in the Milky Way of any existing metal-free first-generation stars -- the so-called Population III stars. However, classical techniques to identify metal-poor stars fail in the bulge because of crowding and reddening. I will present a new, efficient technique to identify metal-poor stars that uses only 2MASS near-infrared and WISE mid-infrared photometry to identify metal-poor stars through their lack of molecular absorption near 4.6 microns. A survey based on this technique has already identified the most metal-poor stars known in the bulge. I will describe the results from this survey and outline how the combination of high-resolution WFIRST-AFTA near-infrared photometry and JWST/NIRCam grism spectroscopy in the bulge will decisively determine whether there are any true "first stars" in our Galaxy.

    Michael D. Schneider ( LLNL )

    Co-authors: W. A. Dawson (LLNL)
    Title: On the joint forward-modeling of WFIRST-AFTA and LSST imaging

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    Abstract: The joint cosmological analysis of WFIRST-AFTA and LSST images that overlap on the sky will be confused by object blending, varying depth- and color-dependent selections, and different pixel scales. For all these reasons a joint forward model of the pixel images of the two surveys is desirable. Based on recent image simulation and galaxy image modeling projects for LSST, I will discuss how to build a consistent probabilistic framework and efficient simulation approach to joint image analysis. Key aspects of any simulation framework include 1) statistical descriptions allowing joint inference of cosmology and properties of the astronomical source population of stars and galaxies, 2) computationally fast descriptions of the telescopes and detectors for systematics marginalization, 3) consistent algorithms to include ancillary data from, e.g., engineering time calibrations or complimentary survey data. I will summarize the approaches we are taking to all of these issues with numerical examples.

    Jeremy Schnittman ( NASA-GSFC )

    Co-authors: John Baker (GSFC); Tyson Littenberg (Northwestern/UAH;) Kailash Sahu (STScI); Nicholas Thieme (UMD)
    Title: Detecting Compact Objects with Microlensing

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    Abstract: We calculate the light curves of galactic bulge stars magnified via microlensing by stellar-mass binary black holes and neutron stars along the line-of-sight. We show the sensitivity to measuring various lens parameters for a range of survey cadences and photometric precision. Astrometric observations with HST and WFIRST will provide powerful additional constraints on the lens parameters and help break fundamental degeneracies of the problem. We discuss the implications of these observations for theories of binary formation and evolution.

    Daniel Scolnic ( KICP at University of Chicago )

    Co-authors: Ryan Foley, University of Illinois.
    Title: A Fully Realized Simulation of the WFIRST SN Survey

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    Abstract: The WFIRST SN survey will be unique in many ways compared to all previous SN surveys. It is therefore vital to accurately simulate the survey and test the strategies and assumptions laid out in the WFIRST-AFTA paper. We use techniques developed for past SN surveys to model each part of the WFIRST SN survey and analysis, from the zeropoints of the observations to the uncertainties in the evolution of SN physics with redshift. We show our best estimates for the breakdown of both the statistical and systematic uncertainties when constraining w0-wa. From out first analysis, we find that both the statistical and systematic uncertainties presented in the AFTA paper are significantly underestimated. We also demonstrate how the WFIRST community can use our simulations so we can best answer questions about how to optimize the WFIRST instruments and strategy.

    Avi Shporer ( JPL )

    Title: Exoplanet synergies between WFIRST and Gaia

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    Abstract: WFIRST will be operating in the post-Gaia era, when all the Gaia data have been made public. Therefore, WFIRST will be able to build on Gaia results and follow-up on its discoveries. I will briefly describe the Gaia mission and discuss possible exoplanet-related synergies between WFIRST and Gaia. This includes using the WFIRST coronagraph to observe planets orbiting bright nearby stars which were detected and their mass was measured astrometrically by Gaia.

    Josh Simon ( Carnegie Observatories )

    Title: Constraints on Fundamental Astrophysics from WFIRST Observations of Milky Way Satellite Galaxies

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    Abstract: A Hubble-class telescope with a very wide field imager would significantly enhance our ability to use the closest galaxies as astrophysical laboratories. I will discuss several applications of WFIRST to nearby dwarf galaxies that can provide key measurements of the stellar initial mass function, the distribution of dark matter in nearly baryon-free systems, and the formation of the faintest galaxies. Some of the required data will be obtained by default during the course of the high latitude survey, while separate GO observing programs would be needed for other measurements. In the latter case, the wide field of WFIRST makes it at least an order of magnitude more efficient than HST.

    Rachel Somerville ( Rutgers University )

    Title: How high-resolution wide-field imaging can help us constrain the physics of galaxy formation

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    Abstract: High-resolution imaging from surveys on the Hubble Space Telescope has allowed us to study the internal structure as well as global properties of galaxies out to 'cosmic high noon' (z~2-3). I will discuss how these observations help us to better understand the most uncertain aspects of our current models of galaxy formation: how 'feedback' from stars, supernovae, and active galactic nuclei couple to the gas in and around galaxies. I will then discuss ways that future wide field surveys could enable further progress in this area.

    David N. Spergel ( Princeton )

    Title: WFIRST-AFTA: A Powerful Tool for Astrophysics

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    Abstract: A 2.4-meter space telescope equipped with a very wide-field infrared camera would revolutionize astrophysics. The transfer of this telescope asset to NASA is a boon to the US scientific community that should be utilized to produce transformative science. With the spatial resolution of HST’s powerful WFC3/IR camera and more than 200 times its field of view, WFIRST-AFTA will enable an exciting GO program. It will measure the expansion history of the universe and growth of structure to better than 1% in narrow redshift bins using several independent methods with aggregate precision of 0.2% or better on multiple cosmological observables. It will study the properties of extrasolar planets through both its microlensing survey and its coronagraph that will characterize giant planets around the nearest stars, and be an important step towards detecting habitable exoEarths.

    Keivan Stassun ( Vanderbilt University )

    Co-authors: Joshua Pepper (Lehigh University); Nathan De Lee (University of Northern Kentucky); Martin Paegert (Vanderbilt University)
    Title: TESS and Galactic Astronomy

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    Abstract: We summarize aspects of the TESS mission that should be of interest beyond exoplanet science to include stellar astrophysics, studies of the Milky Way, and other areas. We briefly summarize key mission design specifications and specifically describe the work of the TESS Science Office's target selection working group to develop a comprehensive catalog of several million target stars across the entire sky. We also briefly discuss value-added stellar parameters that should be obtained from the TESS light curve data soon after launch.

    Massimo Stiavelli ( STScI )

    Title: WFIRST and JWST synergies in the study of First Light

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    Abstract: I will discuss how JWST and WFIRST can be complementary in the study of First Light. I will consider galaxies, AGNs and Population III stars detected through pair-instability supernovae.

    Michael Strauss ( Princeton University )

    Title: Synergies between LSST and WFIRST

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    Abstract: The Large Synoptic Survey Telescope will see first light in late 2019, and its ten-year survey lifetime includes that of WFIRST. LSST will gather six-band (ugrizy) optical data to a coadded depth of r~27.5, and comparable depths in other bands, over 18,000 square degrees. This is wonderfully complementary to the near-infrared photometry and spectroscopy of WFIRST. I will discuss some of the scientific opportunities of the resulting combined photometry, examine possibilities for studies of time-variable phenomena from the two datasets, and talk about some of the data reduction challenges of processing the imaging from the two facilities in an optimal way.

    Rachel Street ( LCOGT )

    Title: What WFIRST can reveal from binary stars

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    Abstract: WFIRST will be able to probe deeper into nearby star forming regions to lower masses than previously possible thanks to its IR bandpasses and low-resolution spectroscopy. The wider field of view will expand the sample of such regions surveyed, thereby providing for the first time a meaningful insight into the IMF. Many of the objects detected will be binaries. Of particular interest is the binary fraction at the extreme low mass end which WFIRST will be able to sample from stellar masses down to planetary. This will greatly aid models of the formation of these objects, which offer multiple channels through which low-mass objects can form.

    In addition, WFIRST's Bulge survey will detect a large sample of binaries both via microlensing of background objects and eclipses found in the high cadence data. Between them, these techniques are sensitive to companion objects of all masses and evolutionary stages both close in and out to separations of tens of AU, creating a unique population study not confined to the solar neighborhood or specific star forming regions.

    Masahiro Takada ( Kavli IPMU )

    Title: Dark Energy Interests in Japan: Subaru SuMIRe project

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    Abstract: There is growing interest in dark energy science in Japan. By fully utilizing the advantage of wide-field capability of 8.2m Subaru Telescope, we are promoting the SuMIRe project (Subaru Measurements of Images and Redshifts). The SuMIRe consists of two components: the wide-field imaging survey with the new prime-focus camera, Hyper Suprime-Cam (HSC) (1400 sq. degrees and i~26mag in depth), and the spectroscopic survey with the prime-focus spectrograph (PFS) (1400 sq. degrees and 0.8 <z <2.4 in redshift coverage). We are just starting the HSC imaging survey for 5 years duration until 2019. PFS is in the instrumentation phase, and we hope to have the engineer first light in 2018 and then start the spectroscopic survey from 2019 for 5 years. The combination of imaging and spectroscopic surveys for the same region of the sky, just as in SDSS, allows for a robust and powerful way of exploring the nature of dark energy. I will describe the details of SuMIRe project, and also discuss a possible synergy with WFIRST.

    Motohide Tamura ( U-Tokyo / NAOJ )

    Co-authors: SEEDS team
    Title: Exoplanet and Disk Imaging With Subaru

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    Abstract: The SEEDS survey of exoplanets and disks is the first Subaru Strategic Program, whose aim is to conduct a direct imaging survey for giant planets as well as protoplanetary/debris disks at a few to a few tens of AU region around 500 nearby solar-type or more massive young stars devoting 120 Subaru nights for 5 years. The targets are composed of five categories spanning the ages of ~1 Myr to ~1 Gyr. Some RV-planet targets with older ages are also observed. The main survey has been almost completed without major instrument troubles. We describe the outline of this survey and present its main results. On-going and future exoplanet instruments for Subaru are also outlined.

    Roeland Van Der Marel ( STScI )

    Co-authors: Jay Anderson (STScI)
    Title: Local Group Proper Motion Science from Wide Field Surveys

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    Abstract: Our knowledge of the dynamics and masses of galaxies in the Local Group has long been limited by the fact that only line-of-sight velocities were available. This introduces significant degeneracies in dynamical models, which can only be resolved by measuring also the velocity components perpendicular to the line of sight. However, beyond the Milky Way, the corresponding proper motions have generally been too small to measure. This has changed over the past decade due to the angular resolution and stability available with HST. This is illustrated by the results from our HST Proper Motion collaboration (HSTPROMO), which have provided new insights into, e.g., the dynamics of stars in the Milky Way tidal streams and metal-poor halo, and into the motions of Milky Way satellites, the Magellanic Clouds, and the Andromeda galaxy. GAIA will further revolutionize our understanding of the Milky Way, but its all-sky survey will not reach faint stars at larger distances. The ASTRO2010 NAS Decadal Survey listed astrometry as an "Area of Unusual Discovery Potential". Indeed, the WFIRST-AFTA mission will open up a whole new parameter space by enabling HST-quality proper motion measurements for faint objects over very wide fields. I will discuss the new science that this will enable, and how WFIRST-AFTA is expected to reshape our understanding of the structure, dynamics and masses of galaxies in the Local Group.

    David Weinberg ( Ohio State University )

    Title: Cosmic Acceleration: From Today to WFIRST

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    Abstract: I will give an assessment of the current state of play in the study of cosmic acceleration, with emphasis on recent results from the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS) and the level of concordance (or not) between expansion history and structure growth measurements. I will discuss what is needed for WFIRST to deliver on its promise as a dark energy mission and what it might discover when it does so. In round numbers, we are now at a stage where expansion history observables are measured at one-percent precision and growth observables at 5-10 percent precision, and our goal for future experiments is to reach sub-percent precision on both tracks. This goal places stringent demands on the quality of observational data and the accuracy of theoretical modeling.

    Daniel Weisz ( Univ. of Washington )

    Title: WFIRST/AFTA Milky Way & Local Group Science

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    Abstract: The high angular resolution capabilities of the Hubble Space Telescope have revolutionized our understanding of the Local Group. Resolving individual stars in Local Group galaxies has provided unique insight into a wide variety of astrophysics including the formation and evolution of the lowest-mass galaxies, cosmic reionization, the stellar IMF, stellar evolution, and the interstellar medium, each of which serve to anchor our understanding of the distant universe. In this talk, I will highlight a selection of science results from resolved star studies in the Local Group and will emphasize areas in which WFIRST has the potential to make substantial new contributions.

    Ned Wright ( UCLA Astronomy )

    Title: Wide-field InfraRed Surveys: WISE and NEOWISE-R

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    Abstract: The Wide-field Infrared Survey Explorer mapped the whole sky in 4 infrared bands centered at 3.4, 4.6, 12 and 22 microns. A two-band search for asteroids in the 3.4 and 4.6 micron bands continued after the solid hydrogen cryogen was depleted. All the data taken from Jan 2010 through Jan 2011 was combined into the AllWISE data release with 747,634,026 sources. WISE data have been used in more than 1000 papers covering asteroids, comets, free floating planets, nearby stars and star formation, galaxies and clusters, ULIRGs and QSOs. After a 2.5 year hibernation, WISE is now reactivated to once again search for Near Earth Objects as NEOWISE-R. Single frame images and single frame detections from NEOWISE-R will be publicly released next year, but a grand coadd of the celestially fixed sky would greatly enhance the time baseline for proper motion, parallax, and variability studies; and also increase the survey sensitivity to galaxies and clusters of galaxies at redshifts up to 2.

    Jennifer Yee ( Harvard-Smithsonian Center for Astrophysics )

    Title: Precursor Science for WFIRST's Microlensing Program

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    Abstract: I will discuss the primary, precursor science programs explored by Study Analysis Group 11, which will maximize the WFIRST microlensing survey. In particular, I will focus on precursor, HST optical imaging of the field, a ground-based, near-IR microlensing survey, and satellite parallax observations of current, ground-based microlensing events. Not only will these programs enhance the WFIRST microlensing planet discoveries, but they also have larger implications for studies of stars, brown dwarfs, black holes and Galactic structure.

    Gail Zasowski ( Johns Hopkins University )

    Title: Dust in the Milky Way and Local Group

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    Abstract: Dust plays an enormous role in our view of the Universe. It absorbs and scatters light from background sources, particularly in the UV to near-IR, and re-radiates the absorbed energy at longer wavelengths. This emitted energy contributes to the local radiation field, and the loss of energy at shorter wavelengths dramatically impacts our perception of the background sources themselves. These effects are particularly problematic in the Milky Way and Local Group, where the sources of interest often lie in front of the integrated line-of-sight extinction and where the scale of the dust clumpiness is often comparable to the region under study. Thus, understanding the large-scale, 3-D distribution of local dust is a crucial issue in many areas of astronomy. I will briefly review the fundamentals of the problem, summarize some recent and ongoing approaches to address it, and then describe the particular advantages that WFIRST may bring to the solution.