TY - JOUR
T1 - Molecular Gas Contents and Scaling Relations for Massive, Passive Galaxies at Intermediate Redshifts from the LEGA-C Survey
AU - Spilker, Justin
AU - Bezanson, Rachel
AU - Barišić, Ivana
AU - Bell, Eric
AU - Lagos, Claudia Del
AU - Maseda, Michael
AU - Muzzin, Adam
AU - Pacifici, Camilla
AU - Sobral, David
AU - Straatman, Caroline
AU - Wel, Arjen Van Der
AU - Dokkum, Pieter Van
AU - Weiner, Benjamin
AU - Whitaker, Katherine
AU - Williams, Christina C.
AU - Wu, Po Feng
N1 - Publisher Copyright:
© 2018. The American Astronomical Society. All rights reserved..
PY - 2018/6/20
Y1 - 2018/6/20
N2 - A decade of study has established that the molecular gas properties of star-forming galaxies follow coherent scaling relations out to z ∼ 3, suggesting remarkable regularity of the interplay between molecular gas, star formation, and stellar growth. Passive galaxies, however, are expected to be gas-poor and therefore faint, and thus little is known about molecular gas in passive galaxies beyond the local universe. Here we present deep Atacama Large Millimeter/submillimeter Array observations of CO(2-1) emission in eight massive (M star ∼ 1011 M o) galaxies at z ∼ 0.7 selected to lie a factor of 3-10 below the star-forming sequence at this redshift, drawn from the Large Early Galaxy Astrophysics Census survey. We significantly detect half the sample, finding molecular gas fractions ≲0.1. We show that the molecular and stellar rotational axes are broadly consistent, arguing that the molecular gas was not accreted after the galaxies became quiescent. We find that scaling relations extrapolated from the star-forming population overpredict both the gas fraction and gas depletion time for passive objects, suggesting the existence of either a break or large increase in scatter in these relations at low specific star formation rate. Finally, we show that the gas fractions of the passive galaxies we have observed at intermediate redshifts are naturally consistent with evolution into local, massive early-type galaxies by continued low-level star formation, with no need for further gas accretion or dynamical stabilization of the gas reservoirs in the intervening 6 billion years.
AB - A decade of study has established that the molecular gas properties of star-forming galaxies follow coherent scaling relations out to z ∼ 3, suggesting remarkable regularity of the interplay between molecular gas, star formation, and stellar growth. Passive galaxies, however, are expected to be gas-poor and therefore faint, and thus little is known about molecular gas in passive galaxies beyond the local universe. Here we present deep Atacama Large Millimeter/submillimeter Array observations of CO(2-1) emission in eight massive (M star ∼ 1011 M o) galaxies at z ∼ 0.7 selected to lie a factor of 3-10 below the star-forming sequence at this redshift, drawn from the Large Early Galaxy Astrophysics Census survey. We significantly detect half the sample, finding molecular gas fractions ≲0.1. We show that the molecular and stellar rotational axes are broadly consistent, arguing that the molecular gas was not accreted after the galaxies became quiescent. We find that scaling relations extrapolated from the star-forming population overpredict both the gas fraction and gas depletion time for passive objects, suggesting the existence of either a break or large increase in scatter in these relations at low specific star formation rate. Finally, we show that the gas fractions of the passive galaxies we have observed at intermediate redshifts are naturally consistent with evolution into local, massive early-type galaxies by continued low-level star formation, with no need for further gas accretion or dynamical stabilization of the gas reservoirs in the intervening 6 billion years.
KW - galaxies: ISM
KW - galaxies: evolution
KW - galaxies: high-redshift
UR - http://www.scopus.com/inward/record.url?scp=85049205648&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85049205648&partnerID=8YFLogxK
U2 - 10.3847/1538-4357/aac438
DO - 10.3847/1538-4357/aac438
M3 - Article
AN - SCOPUS:85049205648
SN - 0004-637X
VL - 860
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 103
ER -