TY - JOUR
T1 - SAGAbg. I. A Near-unity Mass-loading Factor in Low-mass Galaxies via Their Low-redshift Evolution in Stellar Mass, Oxygen Abundance, and Star Formation Rate
AU - Kado-Fong, Erin
AU - Geha, Marla
AU - Mao, Yao Yuan
AU - de los Reyes, Mithi A.C.
AU - Wechsler, Risa H.
AU - Asali, Yasmeen
AU - Kallivayalil, Nitya
AU - Nadler, Ethan O.
AU - Tollerud, Erik J.
AU - Weiner, Benjamin
N1 - Publisher Copyright:
© 2024. The Author(s). Published by the American Astronomical Society.
PY - 2024/5/1
Y1 - 2024/5/1
N2 - Measuring the relation between star formation and galactic winds is observationally difficult. In this work we make an indirect measurement of the mass-loading factor (the ratio between the mass outflow rate and star formation rate) in low-mass galaxies using a differential approach to modeling the low-redshift evolution of the star-forming main sequence and mass-metallicity relation. We use Satellites Around Galactic Analogs (SAGA) background galaxies, i.e., spectra observed by the SAGA Survey that are not associated with the main SAGA host galaxies, to construct a sample of 11,925 spectroscopically confirmed low-mass galaxies from 0.01 ≲ z ≤ 0.21 and measure auroral line metallicities for 120 galaxies. The crux of the method is to use the lowest-redshift galaxies as the boundary condition of our model, and to infer a mass-loading factor for the sample by comparing the expected evolution of the low-redshift reference sample in stellar mass, gas-phase metallicity, and star formation rate against the observed properties of the sample at higher redshift. We infer a mass-loading factor of η m = 0.92 − 0.74 + 1.76 , which is in line with direct measurements of the mass-loading factor from the literature despite the drastically different sets of assumptions needed for each approach. While our estimate of the mass-loading factor is in good agreement with recent galaxy simulations that focus on resolving the dynamics of the interstellar medium, it is smaller by over an order of magnitude than the mass-loading factor produced by many contemporary cosmological simulations.
AB - Measuring the relation between star formation and galactic winds is observationally difficult. In this work we make an indirect measurement of the mass-loading factor (the ratio between the mass outflow rate and star formation rate) in low-mass galaxies using a differential approach to modeling the low-redshift evolution of the star-forming main sequence and mass-metallicity relation. We use Satellites Around Galactic Analogs (SAGA) background galaxies, i.e., spectra observed by the SAGA Survey that are not associated with the main SAGA host galaxies, to construct a sample of 11,925 spectroscopically confirmed low-mass galaxies from 0.01 ≲ z ≤ 0.21 and measure auroral line metallicities for 120 galaxies. The crux of the method is to use the lowest-redshift galaxies as the boundary condition of our model, and to infer a mass-loading factor for the sample by comparing the expected evolution of the low-redshift reference sample in stellar mass, gas-phase metallicity, and star formation rate against the observed properties of the sample at higher redshift. We infer a mass-loading factor of η m = 0.92 − 0.74 + 1.76 , which is in line with direct measurements of the mass-loading factor from the literature despite the drastically different sets of assumptions needed for each approach. While our estimate of the mass-loading factor is in good agreement with recent galaxy simulations that focus on resolving the dynamics of the interstellar medium, it is smaller by over an order of magnitude than the mass-loading factor produced by many contemporary cosmological simulations.
UR - http://www.scopus.com/inward/record.url?scp=85192055000&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85192055000&partnerID=8YFLogxK
U2 - 10.3847/1538-4357/ad3042
DO - 10.3847/1538-4357/ad3042
M3 - Article
AN - SCOPUS:85192055000
SN - 0004-637X
VL - 966
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 129
ER -