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Stars, Gas, and Star Formation of Distant Post-starburst Galaxies

Published version
Peer-reviewed

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Abstract

jats:titleAbstract</jats:title> jats:pWe present a comprehensive multiwavelength study of five post-starburst galaxies with jats:italicM</jats:italic> jats:sub*</jats:sub> > 10jats:sup11</jats:sup> jats:italicM</jats:italic> jats:sub⊙</jats:sub> at jats:italicz</jats:italic> ∼ 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 × 10jats:sup9</jats:sup> jats:italicM</jats:italic> jats:sub⊙</jats:sub> to 10jats:sup11</jats:sup> jats:italicM</jats:italic> jats:sub⊙</jats:sub>, 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 × 10jats:sup10</jats:sup> jats:italicM</jats:italic> jats:sub⊙</jats:sub>. 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.</jats:p>

Description

Keywords

Post-starburst galaxies, Galaxy stellar content, Star formation, Galaxy kinematics, Interstellar medium, Galaxy evolution, Galaxy quenching, Active galactic nuclei

Journal Title

The Astrophysical Journal

Conference Name

Journal ISSN

0004-637X
1538-4357

Volume Title

955

Publisher

American Astronomical Society
Sponsorship
Istituto Nazionale di Astrofisica (INAF) (1.05.12.04.01)
National Science and Technology Council (NSTC) (111-2112-M-002-048-MY2)
National Taiwan University () (112L7439)
National Taiwan University () (112L7318)
EC ∣ ERC ∣ HORIZON EUROPE European Research Council (ERC) (695671)