Roman Virtual Lecture

Dec. 17, 2020

Speaker (Affiliation):
Prabal Saxena (GSFC)

Simulating Roman/CGI Observations of the reflected light exoplanet spectra of the bright, nearby exoplanet ups And d


Simulations of exoplanet albedo profiles are key to planning and interpreting future direct imaging observations. We use the Planetary Spectrum Generator (PSG) to produce simulations of reflected light exoplanet spectra of the bright, nearby exoplanet upsilon Andromedae d, a potential direct imaging target for next-generation facilities. We introduce a new, fast, and accurate sub-sampling technique that enables calculations of disk-integrated spectra one order of magnitude faster than Chebyshev-Gauss sampling for moderate- to high-resolution sampling. Using this method and a first-principles-derived atmosphere for ups And d, we simulate phase-dependent spectra for a variety of different potential atmospheric configurations. The simulated spectra for ups And d include versions with different haze and cloud properties. Based on our combined analysis of this planet’s orbital parameters, phase- and illumination-appropriate model spectra, and realistic instrument noise parameters, we find that ups And d is a potentially favorable direct imaging and spectroscopy target for the Coronagraph Instrument (CGI) on the Nancy Grace Roman Space Telescope. When a noise model corresponding to the Roman CGI SPC spectroscopy mode is included, PSG predicts the time required to reach a signal-to-noise ratio of 10 of the simulated spectra in both the central wavelength bin of the Roman CGI SPC spectroscopy mode (R=50 spectrum) and of the Band 1 HLC imaging mode is approximately 400 and and less than 40 hours, respectively. We also discuss potential pathways to extricating information about the planet and its atmosphere with future observations.