Evidence for late-time feedback from the discovery of multiphase gas in a massive elliptical at z = 0.4

Fakhri S. Zahedy, Hsiao Wen Chen, Erin Boettcher, Michael Rauch, K. Decker French, Ann I. Zabludoff

Research output: Contribution to journalArticlepeer-review

Abstract

We report the first detection of multiphase gas within a quiescent galaxy beyond z ≈ 0. The observations use the brighter image of doubly lensed QSO HE 0047-1756 to probe the interstellar medium (ISM) of the massive (Mstar ≈ 10 M⊙ 11 ) elliptical lens galaxy at z = 0.408 gal . Using Hubble Space Telescope's Cosmic Origins Spectrograph (COS), we obtain a medium-resolution FUV spectrum of the lensed QSO and identify numerous absorption features from H2 in the lens ISM at projected distance d = 4.6 kpc. The H2 column density is log N(H2)/- cm-2 = - 17.8+ 2 2 0.3 0.1 with a molecular gas fraction of f = 2%-5% H2 , roughly consistent with some local quiescent galaxies. The new COS spectrum also reveals kinematically complex absorption features from highly ionized species O VI and N V with column densities log N(O VI) cm-2 = 15.2 ± 0.1 and log N(N V) cm-2 = 14.6 ± 0.1, among the highest known in external galaxies. Assuming the high-ionization absorption features originate in a transient warm (T∼105 K) phase undergoing radiative cooling from a hot halo surrounding the galaxy, we infer a mass accretion rate of∼0.5-1.5 M⊙ yr-1. The lack of star formation in the lens suggests that the bulk of this flow is returned to the hot halo, implying a heating rate of∼1048 erg yr-1. Continuous heating from evolved stellar populations (primarily SNe Ia but also winds from AGB stars) may suffice to prevent a large accumulation of cold gas in the ISM, even in the absence of strong feedback from an active nucleus.

Original languageEnglish (US)
Article numberabc48d
JournalAstrophysical Journal Letters
Volume904
Issue number1
DOIs
StatePublished - Nov 20 2020

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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