The High Latitude Spectroscopic Survey on the Nancy Grace Roman Space Telescope

March 2022 • 2022ApJ...928....1W

Authors • Wang, Yun • Zhai, Zhongxu • Alavi, Anahita • Massara, Elena • Pisani, Alice • Benson, Andrew • Hirata, Christopher M. • Samushia, Lado • Weinberg, David H. • Colbert, James • Doré, Olivier • Eifler, Tim • Heinrich, Chen • Ho, Shirley • Krause, Elisabeth • Padmanabhan, Nikhil • Spergel, David • Teplitz, Harry I.

Abstract • The Nancy Grace Roman Space Telescope will conduct a High Latitude Spectroscopic Survey (HLSS) over a large volume at high redshift, using the near-IR grism (1.0-1.93 μm, R = 435-865) and the 0.28 deg² wide-field camera. We present a reference HLSS that maps 2000 deg² and achieves an emission-line flux limit of 10^-16 erg s^-1 cm^-2 at 6.5σ, requiring ~0.6 yr of observing time. We summarize the flowdown of the Roman science objectives to the science and technical requirements of the HLSS. We construct a mock redshift survey over the full HLSS volume by applying a semianalytic galaxy formation model to a cosmological N-body simulation and use this mock survey to create pixel-level simulations of 4 deg² of HLSS grism spectroscopy. We find that the reference HLSS would measure ~10 million Hα galaxy redshifts that densely map large-scale structure at z = 1-2 and 2 million [O III] galaxy redshifts that sparsely map structures at z = 2-3. We forecast the performance of this survey for measurements of the cosmic expansion history with baryon acoustic oscillations and the growth of large-scale structure with redshift-space distortions. We also study possible deviations from the reference design and find that a deep HLSS at f _line > 7 × 10^-17 erg s^-1 cm^-2 over 4000 deg² (requiring ~1.5 yr of observing time) provides the most compelling stand-alone constraints on dark energy from Roman alone. This provides a useful reference for future optimizations. The reference survey, simulated data sets, and forecasts presented here will inform community decisions on the final scope and design of the Roman HLSS.

Links

• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2022ApJ...928....1W
• PDF https://iopscience.iop.org/article/10.3847/1538-4357/ac4973/pdf
• PREPRINT http://arxiv.org/abs/2110.01829
• ELECTR https://doi.org/10.3847%2F1538-4357%2Fac4973