An Empirical Approach to Cosmological Galaxy Survey Simulation: Application to SPHEREx Low-Resolution Spectroscopy

TL;DR

This paper develops a data-driven galaxy population model based on COSMOS survey data to simulate and predict the performance of the SPHEREx cosmological mission, enabling realistic end-to-end mission simulations.

Contribution

It introduces a novel, empirically constrained galaxy simulation framework tailored for SPHEREx, capturing galaxy complexity for accurate mission performance predictions.

Findings

Simulation reproduces known galaxy properties accurately

Framework enables realistic end-to-end mission performance predictions

Potential applications extend to future cosmology missions

Abstract

Highly accurate models of the galaxy population over cosmological volumes are necessary in order to predict the performance of upcoming cosmological missions. We present a data-driven model of the galaxy population constrained by deep 0.1-8 $\rm \mu m$ imaging and spectroscopic data in the COSMOS survey, with the immediate goal of simulating the spectroscopic redshift performance of the proposed SPHEREx mission. SPHEREx will obtain over the full-sky $R\sim41$ spectrophotometry at moderate spatial resolution ($\sim6"$) over the wavelength range 0.75-4.18 $\rm \mu m$ and $R\sim135$ over the wavelength range 4.18-5 $\rm \mu m$. We show that our simulation accurately reproduces a range of known galaxy properties, encapsulating the full complexity of the galaxy population and enables realistic, full end-to-end simulations to predict mission performance. Finally, we discuss potential applications of the simulation framework to future cosmology missions and give a description of released data products.