Roman Galactic Plane Early Science White Paper Submitted
Proposed observational plan for a Galactic Roman Infrared Plane Survey (GRIPS) overlaid on an optical Gaia star count map which shows the high level of extinction in the Galactic plane. The survey area is shown in white; the grey contours of COBE/DIRBE 4.9 μm emission (at 1,2,4,8, and 16 MJy/sr), which outline the stellar disk and bulge, fit within the survey area. Of the 991 sq.deg covered, only 2.8 sq.deg / 0.3 sq.deg has high angular resolution coverage by HST (yellow)/ESO-VLT GALACTICNUCLEUS program (red). Approximate area of the 1.96 sq.deg Roman Galactic Bulge Time Domain Survey is shown in blue. Four example star-forming fields— Galactic Center, NGC 6357, M8, and M20—are noted in cyan. The combination of lowered extinction in the K band with high angular resolution will allow for the identification of 120 billion sources, a significant fraction of the Milky Way’s stars. For comparison, this area contains only 0.38 billion sources in Gaia eDR3.
News • October 22nd, 2021
A wide area Galactic survey with Roman will characterize most of the stellar content of our Galaxy and will provide unique information on both the history of Galaxy formation, and the on-going process of star formation in vastly different environments, as Roman is uniquely suited to deal with the confusion and extinction prevalent in the plane of the Galaxy. We propose a 991 sq.deg survey of the inner Galactic plane, spanning latitudes |b| < 3° over the longitude range |l| < 60°, with additional latitude coverage up to |b| < 10° in the bulge (|l| < 10°). We will leverage the Wide Field Instrument in three filters: F106, F158, and F213. The F106 filter was chosen to provide continuous wavelength coverage with Rubin at shorter wavelengths, and the F213 filter was selected to maximize the potential of Roman in dust-enshrouded regions deep in the plane. F158 will complement the other two filters and allow building diagnostics for the identification of the surveyed stellar populations. We propose an integration time of 55 seconds per filter, reaching a minimum depth of 25.5 mag in F106, 25.3 mag in F158, and 24.7 mag in F213. We will need approximately 3600 pointings for our 991 sq.deg survey area, yielding an estimated total time of 673 hours. By extrapolating to our proposed footprint the Penny et al. (2019) stellar density estimates based on the Besançon model, we estimate that up to 120 billion unique stellar sources shall be characterized, as compared to the 0.38 billion sources in Gaia eDR3.
