ALMA Measures Rapidly Depleted Molecular Gas Reservoirs in Massive Quiescent Galaxies at z similar to 1.5

Research output: Contribution to journalJournal articlepeer-review

  • Christina C. Williams
  • Justin S. Spilker
  • Katherine E. Whitaker
  • Romeel Dave
  • Charity Woodrum
  • Brammer, Gabriel
  • Rachel Bezanson
  • Desika Narayanan
  • Benjamin Weiner

We present Atacama Large Millimeter/submillimeter Array (ALMA) CO(2-1) spectroscopy of six massive (log(10) M-*/M-circle dot > 11.3) quiescent galaxies at z similar to 1.5. These data represent the largest sample using CO emission to trace molecular gas in quiescent galaxies above z > 1, achieving an average 3 sigma sensitivity of M-H2 similar to 10(10)M(circle dot). We detect one galaxy at 4 sigma significance and place upper limits on the molecular gas reservoirs of the other five, finding molecular gas mass fractions M-H2/M-* = f(H2) <2%-6% (3 sigma upper limits). This is 1-2 orders of magnitude lower than coeval star-forming galaxies at similar stellar.mass, and comparable to galaxies at z.=.0 with similarly low specific star formation rate (sSFR). This indicates that their molecular gas reservoirs were rapidly and efficiently used up or destroyed, and that gas fractions are uniformly low ( 12 by z similar to 4 that halt the accretion of baryons early in the universe. Our data are consistent with a simple picture where galaxies truncate accretion and then consume the existing gas at or faster than typical main-sequence rates. Alternatively, we cannot rule out that these galaxies reside in lower.mass halos, and low gas fractions may instead reflect either stronger feedback, or more efficient gas consumption.

Original languageEnglish
Article number54
JournalAstrophysical Journal
Volume908
Issue number1
Number of pages15
ISSN0004-637X
DOIs
Publication statusPublished - 11 Feb 2021

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