# DESI survey validation data in the COSMOS/HSC field: Cool gas trace main sequence star-forming galaxies at the cosmic noon

## TL;DR

This study uses DESI validation data to analyze the gaseous halos of star-forming galaxies at cosmic noon, revealing correlations between gas absorption features and galaxy properties, and evidence of feedback processes.

## Contribution

First to utilize DESI validation data for CGM studies at high redshift, providing new insights into gas-galaxy interactions and evolution during cosmic noon.

## Key findings

- Strong MgII absorption correlates with star formation rate within 250 kpc.
- Covering fraction of MgII evolves significantly in main-sequence galaxies from z=0.9 to 2.2.
- Detection of gas out of virial radius suggests feedback effects.

## Abstract

We present the first result in exploring the gaseous halo and galaxy correlation using the Dark Energy Spectroscopic Instrument (DESI) survey validation data in the Cosmic Evolution Survey (COSMOS) and Hyper Suprime-Cam (HSC) field. We obtain the multiphase gaseous halo properties in the circumgalactic medium (CGM) by using 115 quasar spectra (S/N > 3). We detect MgII absorption at redshift 0.6 < z < 2.5, CIV absorption at 1.6 < z < 3.6, and HI absorption associated with the MgII and CIV. By cross-matching the COSMOS2020 catalog, we identify the MgII and CIV host galaxies in ten quasar fields at 0.9 < z < 3.1. We find that within the impact parameter of 250 kpc, a tight correlation is seen between strong MgII equivalent width and the host galaxy star formation rate. The covering fraction fc of strong MgII selected galaxies, which is the ratio of absorbing galaxy in a certain galaxy population, shows significant evolution in the main-sequence galaxies and marginal evolution in all the galaxy populations within 250 kpc at 0.9 < z < 2.2. The fc increase in the main-sequence galaxies likely suggests the co-evolution of strong MgII absorbing gas and the main-sequence galaxies at the cosmic noon. Furthermore, several MgII and CIV absorbing gas is detected out of the galaxy virial radius, tentatively indicating the feedback produced by the star formation and/or the environmental effects.