Simulating continuum-based redshift measurement in the $\mathit{\text{Roman’s}}$ High Latitude Spectroscopy Survey

We investigate the capability of the $\mathit{\text{Nancy}}\mathit{\text{Grace}}\mathit{\text{Roman}}\mathit{\text{Space}}\mathit{\text{Telescope’s}}\mathit{\text{(Roman)}}$ Wide-Field Instrument (WFI) G150 slitless grism to detect red, quiescent galaxies based on the current reference survey. We simulate dispersed images for $\mathit{\text{Roman}}$ reference High-Latitude Spectroscopic Survey (HLSS) and analyze two-dimensional spectroscopic data using the grism Redshift and Line Analysis (\verb|Grizli|) software. This study focus on assessing $\mathit{\text{Roman}}$ grism’s capability for continuum-level redshift measurement for a redshift range of $0.5\le z\le 2.5$. The redshift recovery is assessed by setting three requirements of: ${\sigma }_z=\frac{\mid z-z_{\mathrm{t}\mathrm{r}\mathrm{u}\mathrm{e}}\mid }{1+z}\le 0.01$, signal-to-noise ratio (S/N) $\ge 5$ and the presence of a single dominant peak in redshift likelihood function. We find that, for quiescent galxaies, the reference HLSS can reach a redshift recovery completeness of $\ge 50\mathrm{\%}$ for F158 magnitude brighter than 20.2 mag. We also explore how different survey parameters, such as exposure time and the number of exposures, influence the accuracy and completeness of redshift recovery, providing insights that could optimize future survey strategies and enhance the scientific yield of the $\mathit{\text{Roman}}$ in cosmological research.