Stars, Gas, and Star Formation of Distant Post-starburst Galaxies
Journal
The Astrophysical Journal
Journal Volume
955
Journal Issue
1
Start Page
75
ISSN
0004-637X
1538-4357
Date Issued
2023-09-01
Author(s)
Rachel Bezanson
Francesco D’Eugenio
Anna R. Gallazzi
Jenny E. Greene
Michael V. Maseda
Katherine A. Suess
Arjen van der Wel
Abstract
We present a comprehensive multiwavelength study of five post-starburst galaxies with M * > 1011 M ⊙ at z ∼ 0.7, examining their stars, gas, and current and past star formation activities. Using optical images from the Subaru Telescope and Hubble Space Telescope, we observe a high incidence of companion galaxies and low surface brightness tidal features, indicating that quenching is closely related to interactions between galaxies. From optical spectra provided by the LEGA-C survey, we model the stellar continuum to derive the star formation histories and show the stellar masses of progenitors ranging from 2 × 109 M ⊙ to 1011 M ⊙, undergoing a burst of star formation several hundred million years prior to observation, with a decay timescale of ∼100 Myr. Our Atacama Large Millimeter/submillimeter Array observations detect CO(2-1) emission in four galaxies, with the molecular gas spreading over up to >1″, or ∼10 kpc, with a mass of up to ∼2 × 1010 M ⊙. However, star-forming regions are unresolved by either the slit spectra or 3 GHz continuum observed by the Very Large Array. Comparisons between the star formation rates (SFRs) and gas masses, and the sizes of CO emission and star-forming regions suggest a low star-forming efficiency. We show that the SFRs derived from IR and radio luminosities with commonly used calibrations tend to overestimate the true values because of the prodigious amount of radiation from old stars and the contribution from active galactic nuclei (AGNs), as the optical spectra reveal weak AGN-driven outflows.
SDGs
Publisher
American Astronomical Society
Type
journal article