TY - JOUR
T1 - The MASSIVE survey - XI. What drives the molecular gas properties of early-type galaxies
AU - Davis, Timothy A.
AU - Greene, Jenny E.
AU - Ma, Chung Pei
AU - Blakeslee, John P.
AU - Dawson, James M.
AU - Pandya, Viraj
AU - Veale, Melanie
AU - Zabel, Nikki
N1 - Publisher Copyright:
© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.
PY - 2019/6/11
Y1 - 2019/6/11
N2 - In this paper, we study the molecular gas content of a representative sample of 67 of the most massive early-type galaxies (ETGs) in the local universe, drawn uniformly from the MASSIVE survey. We present new Institut de Radioastronomie Millimétrique (IRAM) 30-m telescope observations of 30 of these galaxies, allowing us to probe the molecular gas content of the entire sample to a fixed molecular-to-stellar mass fraction of 0.1 per cent. The total detection rate in this representative sample is 25+5.9-4.4 per cent, and by combining the MASSIVE and atlas3D molecular gas surveys, we find a joint detection rate of 22.4+2.4-2.1 per cent. This detection rate seems to be independent of galaxy mass, size, position on the Fundamental Plane, and local environment. We show here for the first time that true slow rotators can host molecular gas reservoirs, but the rate at which they do so is significantly lower than for fast rotators. Objects with a higher velocity dispersion at fixed mass (a higher kinematic bulge fraction) are less likely to have detectable molecular gas, and where gas does exist, have lower molecular gas fractions. In addition, satellite galaxies in dense environments have ≈0.6 dex lower molecular gas-to-stellar mass ratios than isolated objects. In order to interpret these results, we created a toy model, which we use to constrain the origin of the gas in these systems. We are able to derive an independent estimate of the gas-rich merger rate in the low-redshift universe. These gas-rich mergers appear to dominate the supply of gas to ETGs, but stellar mass loss, hot halo cooling, and transformation of spiral galaxies also play a secondary role.
AB - In this paper, we study the molecular gas content of a representative sample of 67 of the most massive early-type galaxies (ETGs) in the local universe, drawn uniformly from the MASSIVE survey. We present new Institut de Radioastronomie Millimétrique (IRAM) 30-m telescope observations of 30 of these galaxies, allowing us to probe the molecular gas content of the entire sample to a fixed molecular-to-stellar mass fraction of 0.1 per cent. The total detection rate in this representative sample is 25+5.9-4.4 per cent, and by combining the MASSIVE and atlas3D molecular gas surveys, we find a joint detection rate of 22.4+2.4-2.1 per cent. This detection rate seems to be independent of galaxy mass, size, position on the Fundamental Plane, and local environment. We show here for the first time that true slow rotators can host molecular gas reservoirs, but the rate at which they do so is significantly lower than for fast rotators. Objects with a higher velocity dispersion at fixed mass (a higher kinematic bulge fraction) are less likely to have detectable molecular gas, and where gas does exist, have lower molecular gas fractions. In addition, satellite galaxies in dense environments have ≈0.6 dex lower molecular gas-to-stellar mass ratios than isolated objects. In order to interpret these results, we created a toy model, which we use to constrain the origin of the gas in these systems. We are able to derive an independent estimate of the gas-rich merger rate in the low-redshift universe. These gas-rich mergers appear to dominate the supply of gas to ETGs, but stellar mass loss, hot halo cooling, and transformation of spiral galaxies also play a secondary role.
KW - ISM: molecules
KW - galaxies: ISM
KW - galaxies: elliptical and lenticular, cD
KW - galaxies: evolution
KW - galaxies: interactions
KW - stars: mass-loss
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U2 - 10.1093/mnras/stz871
DO - 10.1093/mnras/stz871
M3 - Review article
AN - SCOPUS:85072240426
SN - 0035-8711
VL - 486
SP - 1404
EP - 1423
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 1
ER -