Through a wide variety of community defined surveys, the Roman Space Telescope will greatly expand our sampling of the structures, colors and spectroscopic properties of galaxies over a significant fraction of cosmic time. These datasets will enable the discovery of rare objects and allow us to track the growth of normal galaxies as a function of environment, advancing our understanding of galaxy evolution, and providing a solid foundation against which to test and develop models that link star formation and black hole growth to galactic dark matter halos and large scale structure. This session will bring together observers and theorists to discuss how to optimize both the observing strategy and the simulation strategy to make the most incisive tests of theoretical models.
The Nancy Grace Roman Space Telescope (formerly WFIRST) is a NASA flagship mission planned for launch in the mid 2020s. Roman will perform breakthrough science in dark energy cosmology, exoplanet microlensing, and NIR sky surveys with its Wide Field Instrument. Roman will also feature the Coronagraph Instrument, a technology demonstration that will directly image and take spectra of exoplanetary systems using several novel technologies together for the first time in space. This session will cover the status of the project and upcoming opportunities for community involvement in planning and executing the science and technology demonstration aspects of Roman.
Oral Session Talks
High precision redshifts for Type Ia SNe with the Nancy Grace Roman Space Telescope prism - B. Joshi (JHU) et al.
(Monday, June 13, 9:00–10:00 a.m. PDT)
We present results from simulating slitless spectroscopic observations with the Nancy Grace Roman Space Telescope's (Roman) Wide-Field Instrument (WFI) prism. The objective of this work is to quantify the efficiency of recovered type Ia supernovae (SN Ia) redshifts, as a function of prism exposure time, to guide planning for future SN Ia observing programs on Roman. Generating the 2D dispersed images and extracting 1D spectra is done with the slitless spectroscopy package pyLINEAR along with custom written software. From the analysis of ~1700 simulated SNe Ia prism spectra, we show the efficiency of recovering SNe redshifts to z>~3.0 highlighting the exceptional sensitivity of the Roman prism. We find that a 3 hour spectroscopic exposure time for prism spectra should suffice to achieve ~50 % redshift completeness for SN with 1 < z < 2. Implications for cosmological studies with Roman prism spectra of SNe Ia are also discussed.
Paving the way for JWST and Roman with Theory and Simulations - L.Y.A. Yung (NASA Goddard Space Flight Center)
(Monday, June 13, 10:00–11:30 a.m. PDT)
NASA's JWST and Roman will be the observation powerhouse of the 2020s and will help us see deeper and wider into the high-redshift Universe. In order to maximize their survey efficiency and scientific capabilities, theoretical models and simulations play an important role in forecasting the magnitude, number density, and spatial distribution of expected sources. Furthermore, these physical models are also essential to the interpretation of their intrinsic properties and physical origins. In this seminar, I will showcase the wide range of predictions and data products to be released with the two upcoming papers in the Semi-analytic forecasts series. I will also highlight some of the galaxy formation physics that are expected to be constrained by upcoming observations. These predictions are made with the well-established Santa Cruz semi-analytic model (SAM) and have been shown to perform extremely well at reproducing a variety of observed constraints for galaxies and AGN observed in the past. I will also give a brief demonstration on how they are used in the planning of upcoming JWST galaxy surveys and how to gain access to these publicly available datasets.
3D datacube reconstruction using Roman slitless prism spectra - T. Astraatmadja (STScI)
(Wednesday, June 15, 10:00–11:30 a.m. PDT)
One of the Nancy Grace Roman Space Telescope's objectives is to elucidate the nature of dark energy using Type Ia Supernovae (SNe Ia). Proposed surveys will use a combination of wide-field imaging and slitless spectroscopy, but since SNe Ia spectra will be contaminated by their host galaxies, removing the host galaxy spectrum accurately is important. A clean, uncontaminated SN Ia spectrum improves the accuracy of the determination of luminosity distances as well as the intrinsic brightness of the supernova, and hence, better determination of the dark energy equation of state parameters, w0 and wa. To this end, we have developed a datacube reconstruction algorithm that uses the host galaxy spectra observed at various roll angles during the course of the survey. For a supernova in this galaxy, the reconstructed datacube can then be used for host galaxy subtraction of the SN+galaxy spectra. We generate simulated Roman data using SDSS images and redshift-dependent star formation models to create synthetic datacubes of plausible galaxies at various redshifts. These datacubes are then convolved with the Roman Space Telescope optical throughputs using the most current characterization of the optical system and detectors. We use a realistic noise model based on the known properties of the detector. n this presentation we show results from our analysis of the resulting host-galaxy-subtracted noisy-spectra of SNe Ia and evaluate how well we can recover the SNe Ia spectra given the statistical and systematic uncertainties of different survey observing strategies.
iPoster-Plus Sessions
The Roman Space Telescope Science Operations Center: Overview of Software and Data Simulation Tools - R. Cosentino (STScI)
(Tuesday, June 14, 9:00–10:00 a.m. PDT)
The 2.4m Nancy Grace Roman Space Telescope will be NASA's next flagship astrophysics mission after JWST, with launch planned for no later than July 2027 and an operational baseline of five years. Roman is a survey mission by-design, with the majority of the prime mission dedicated to three core surveys: the High Latitude Time Domain Survey, the High Latitude Wide Area Survey, and the Galactic Bulge Time Domain Survey. Approximately 25% of the observing time will be dedicated to General Astrophysics Survey observations which extend the scientific aims of the core surveys, and approximately 5% of prime mission time will be devoted to a coronagraphic technology demonstration. The Wide FieldInstrument (WFI) is the central observational engine for these surveys, with comparable sensitivity and resolution to Hubble, but with a field of view 100 times larger. The Space Telescope Science Institute (STScI) is the Science Operations Center (SOC) for Roman, with leadership over the mission's scheduling, archive, and most WFI-imaging related systems (including data processing, calibration, user support). In this presentation, we highlight the resources available from the Roman SOC which can be used to enable preparatory Roman science and explore the capabilities of the WFI. This includes a point-spread function (PSF) simulator, an exposure time calculator, and an image simulator. Lastly, we will present a high-level overview of how archival Roman science will be enabled by SOC resources, including a cloud-based science platform, a database of empirical PSFs, and high-level value-added catalogs.
Below the iceberg: Low surface brightness astronomy with HST, Euclid, and Roman - A. Borlaff and P. Marcum (NASA Ames)
(Wednesday, June 15, 9:00–10:00 a.m. PDT)
Our current view of the universe is tightly limited by the light intensity ranges that we are able to detect. Like icebergs partially afloat, apparently well-defined and non-interacting galaxies such as M31 reveal a myriad of satellites, halos, and tidal tails when observed at surface brightness magnitudes lower than 30 mag arcsec⁻². Such structures are not always predicted by current Lambda-CDM models, making deep optical and NIR imaging the next frontier for galaxy evolution and cosmology. Extended low surface brightness sources like outer galactic discs, stellar halos, ultra-diffuse galaxies, or the intracluster light trace provide strong observational tests for cosmology and the structure of Dark Matter. Nevertheless, these features are thousands of times dimmer than the sky background, requiring an unprecedented advance in image processing to push the surface brightness limits to such faint levels. Upcoming observatories like NASA/Nancy Grace Roman or ESA/Euclid have the potential to become major cornerstones for the study of galactic formation and evolution, not only at high redshift but also at the dim and extended envelopes of the objects in the Local Universe. In this contribution, we describe some of the most important technical advances of deep astronomical imaging from space, including source detection, in-orbit detector calibration, as well stray-light correction. By using specific techniques to minimize unwanted systematic effects, structures can be detected down to ~31 mag arcsec⁻² in Hubble Space Telescope images. These new techniques make it possible to reveal the large scale structures that surround the galaxies with the HST, which will be critical for the Euclid/VIS survey (Borlaff et al. 2021b) and the Wide Field Instrument aboard the Nancy Grace Roman Space Telescope. We demonstrate these methods in a new version of the WFC3/IR Hubble Ultra Deep Field (ABYSS HUDF, Borlaff et al. 2019), which improves the detection of extended stellar halos that were invisible until now, revealing that they were double their size at z=0.6-1.0. This new methodology will be fundamental for future space missions with an extremely wide field of view if we want to exploit their capabilities to their true limit, providing unique datasets to study the traces of cosmological evolution in the local Universe and beyond.
A High Fidelity Spectroscopic Simulation Pipeline for Nancy Grace Roman Space Telescope Grism Data - A. Gabrielpillai (NASA GSFC) et al.
(Wednesday, June 15, 9:00–10:00 a.m. PDT)
The Nancy Grace Roman Space Telescope will measure emission lines from millions of emission line galaxies (ELGs) using grism spectroscopy in its wide area survey, and will be capable of medium- and deep-field observations with potential to identify much fainter objects including z > 7 Lyman alpha galaxies. We present our simulation pipeline showcasing the robust capability of Roman spectroscopy. We use Hubble Space Telescope images and detailed spectral energy distribution fitting to create a realistic Roman foreground scene with a focus on ELGs. This scene forms the basis of an upcoming data release and associated data challenge to the astronomy community.
NASA Hyperwall Talks (NASA exhibit)
Obscured AGN – Hiding High Growth at the Cosmic Noon - Andreea Petric (STScI)
(Monday, June 13, 9:10–9:22 a.m. PDT)
Dr. Andreea Petric from the Space Telescope Science Institute, talking about future Roman Space Telescope discoveries of obscured Active Galactic Nuclei.
Paving the way for Big Eyes with Theory and Simulations - Aaron Yung (NASA GSFC)
(Monday, June 13, 6:16–6:28 p.m. PDT)
Dr. Aaron Yung from NASA Goddard presents theoretical simulations that guide the design of Webb and Roman surveys for galaxies in the early Universe. Dr. Yung will present simulated JWST images and the making-of for these physically accurate predictions.
Overview of the Nancy Grace Roman Space Telescope Coronagraph Instrument and Its Technology Demonstration - R. Zellem (NASA JPL)
(Tuesday, June 14, 9:10–9.22 a.m. PDT)
Dr. Robert Zellem from NASA JPL presents the Nancy Grace Roman Space Telescope Coronagraph Instrument, which will be the first high-performance stellar coronagraph using active wavefront control for deep starlight suppression in space, providing unprecedented levels of contrast, spatial resolution, and sensitivity for astronomical observations in the optical. During its Technology Demonstration phase, the Coronagraph will resolve the signal of an exoplanet via photometry and spectroscopy and directly image and measure the polarization of disks, providing a critical intermediate step toward establishing the technology and methods that will potentially be used with a future UVIOR mission. Here, I present the Roman Coronagraph’s design and capability as well as some anticipated results from its technology demonstration.
Roman Science Operations, SOC Data Management System - H. Ferguson (STScI)
(Wednesday, June 15, 9:22–9:34 a.m. PDT)
This presentation by Dr. Harry Ferguson will highlight the data management plans at the STScI Science Operations Center (SOC). Standard pipeline processing for the Wide Field Instrument will remove the instrument signatures and rectify and co-add images multiple images of the same field. The pipeline will generate catalogs of sources, including variable sources. The SOC will also provide tools to assist with simulating Roman data and to provide effective point-spread functions.
The Roman Space Telescope and You - D. Benford (NASA HQ)
(Thursday, June 16, 5:40–5:52 p.m. PDT)
The Nancy Grace Roman Space Telescope will revolutionize space-based astronomy with its unprecedented combination of sensitivity, angular resolution, and survey speed. With less than five years to launch, now is the time to prepare for the flood of science it will enable. Dr. Dominic Benford from NASA HQ presents a new proposal opportunity that is available this year for *you* to be involved.
The Nancy Grace Roman Space Telescope - R. Hounsell (UMBC/GSFC)
(Thursday, June 16, 5:40–5:52 p.m. PDT)
Dr. Rebekah Hounsell from the University of Maryland Baltimore County and NASA Goddard presents the Roman mission and the core surveys it plans to conduct.
