Stellar feedback drives the baryon deficiency in low-mass galaxies

TL;DR

This study provides observational evidence that stellar feedback causes low-mass galaxies to lose baryons by driving outflows capable of escaping their dark matter halos, affecting baryon retention.

Contribution

It offers the first large-scale observational evidence linking stellar feedback-driven outflows to baryon deficiency in low-mass galaxies.

Findings

Star formation driven outflows are detected in Mg II absorption lines.

Outflows from low-mass galaxies can escape beyond dark matter halos.

Stellar feedback influences baryon retention in low-mass galaxies.

Abstract

Stellar feedback, as a key process regulating the baryon cycle, is thought to greatly redistribute baryonic material inside and outside the dark matter halos (DMHs), however the observational evidences are lacking. Through stacking analyses of ~400,000 galaxy spectra from Dark Energy Spectroscopic Instrument (DESI), we find star formation driven cool outflows in Mg II absorption line. Assuming only gravity acts on the launched gas, our calculations reveal that outflows from low mass galaxies ($M_*<10^{10}\,\rm M_\odot$) are capable of escaping beyond the DMHs, which aligns well with our finding in the circumgalactic medium (CGM) absorption along the minor-axes of galaxies using background quasars. This research offers indirect evidence that stellar feedback drives the low baryon retention rate in low-mass haloes, implicating that baryonic processes within galaxies are connected with the diffuse matter beyond the DMHs.