ESpRESSO -- Forward modeling Roman Space Telescope spectroscopy

TL;DR

ESpRESSO is a software tool that simulates Roman Space Telescope slitless spectroscopy, combining archival imaging with spectral models to create realistic mock observations for survey planning and analysis.

Contribution

It introduces a comprehensive simulation suite for Roman grism observations, including background, optical distortions, and source injection, enhancing future spectral data analysis capabilities.

Findings

Realistic simulation of Roman grism observations with background and optical distortions

Ability to inject and analyze custom sources and spectral features

High completeness for Lyα emitter detection in simulated surveys

Abstract

We describe the software package $\texttt{ESpRESSO}$ - [E]xtragalactic [Sp]ectroscopic [R]oman [E]mulator and [S]imulator of [S]ynthetic [O]bjects, created to emulate the slitless spectroscopic observing modes of the Nancy Grace Roman Space Telescope (Roman) Wide Field Instrument (WFI). We combine archival Hubble Space Telescope (HST) imaging data of comparable spatial resolution with model spectral energy distributions to create a data-cube of flux density as a function of position and wavelength. This data-cube is used for simulating a nine detector grism observation, producing a crowded background scene which model field angle dependent optical distortions expected for the grism. We also demonstrate the ability to inject custom sources using the described tools and pipelines. In addition, we show that spectral features such as emission line pairs are unlikely to be mistaken as off order contaminating features and vice versa. Our result is a simulation suite of half of the eighteen detector array, with a realistic background scene and injected Ly$\alpha$ emitter (LAE) galaxies, realized at 25 position angles (PAs), 12 with analogous positive and negative dithers, Using an exposure time of 10ks per PA, the full PA set can be used as a mock deep Roman grism survey with high (synthetic) LAE completeness for developing future spectral data analysis tools.