Simulating properties of emission line galaxies from Nancy Grace Roman Space Telescope

TL;DR

This study uses a semi-analytic galaxy formation model to simulate emission line galaxy properties for the Nancy Grace Roman Space Telescope, validating predictions against observational data and forecasting survey completeness.

Contribution

It provides a validated galaxy mock catalog for Roman, predicting emission line detection completeness and aiding survey planning.

Findings

Model predictions align with observational data across redshifts.

Predicted survey completeness exceeds 94% at specified flux limits.

Roman survey completeness is comparable to Euclid's at similar flux thresholds.

Abstract

We simulate the emission line galaxy properties for the Nancy Grace Roman Space Telescope by creating a 4 deg$^{2}$ galaxy mock catalog using Galacticus, a semi-analytic model (SAM) for galaxy formation and evolution. The simulated galaxy properties include emission line luminosity, equivalent width (EW), broad band photometry, and spectral energy distribution (SED). We compare this mock catalog with the latest observational data from WISP and MOSDEF. We find that our Galacticus model makes predictions consistent with observational data, over a wide redshift range for multiple emission lines. We use this validated galaxy mock catalog to forecast the photometric completeness of H$\alpha$ and [OIII] emission lines as a function of line flux cut and H band magnitdue cut, for both Roman and Euclid-like surveys. Our prediction for the photometric completeness of a Euclid-like survey is in good agreement with previous work based on WISP data. Our predictions for the photometric completeness of possible implementations of the Roman High Latitude Wide Area Spectroscopic Survey (HLWASS) provides key input for the planning of such a survey. We find that at H = 24, a Euclid-like survey to the line flux limit of 2$\times 10^{-16}\,$erg/s/cm$^2$ is 97\% complete, while a Roman HLWASS to the line flux limit of $10^{-16}\,$erg/s/cm$^2$ is only 94.6\% complete (it becomes 98\% complete at H = 25).