Combined CO and Dust Scaling Relations of Depletion Time and Molecular Gas Fractions with Cosmic Time, Specific Star-formation Rate, and Stellar Mass
Reinhard Genzel
(1)
,
L. J. Tacconi
(1)
,
Dieter Lutz
(1)
,
Amélie Saintonge
(2)
,
S. Berta
(1)
,
Benjamin Magnelli
(3)
,
Françoise Combes
(4, 5)
,
Santiago García-Burillo
(6)
,
Roberto Neri
(7)
,
Alberto D. Bolatto
(8)
,
Thierry Contini
(9)
,
S. J. Lilly
(10)
,
Jérémie Boissier
(7)
,
Frédéric Boone
(9)
,
N. Bouché
(9)
,
Frédéric Bournaud
(11)
,
Andreas Burkert
(1)
,
Marcella Carollo
(10)
,
L. Colina
(12)
,
Michael C. Cooper
(13)
,
P. Cox
(14)
,
C. Feruglio
(7)
,
Natascha M. Förster Schreiber
(1)
,
Jonathan Freundlich
(4, 5)
,
J. Graciá-Carpio
(1)
,
Stéphanie Juneau
(11)
,
K. Kovac
(10)
,
Magdalena Lippa
(1)
,
Thorsten Naab
(15)
,
Philippe Salomé
(4, 5)
,
Alvio Renzini
(16)
,
Amiel Sternberg
(17)
,
F. Walter
(15)
,
Benjamin Weiner
(18)
,
Achim Weiss
(19)
,
Stijn Wuyts
(1)
1
MPE -
Max-Planck-Institut für Extraterrestriche Physik
2 UCL - University College of London [London]
3 Rheinische Friedrich-Wilhelms-Universität Bonn
4 LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique
5 Galaxies et cosmologie
6 Observatorio Astronomico Nacional, Madrid
7 IRAM - Institut de RadioAstronomie Millimétrique
8 Department of Astronomy, University of Maryland
9 IRAP - Institut de recherche en astrophysique et planétologie
10 ETH Zürich - Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich]
11 DAPNIA - Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée
12 DAMIR/CSIC - Department of Molecular and Infrared Astrophysics, Consejo Superior de Investigaciones Científicas
13 Department of Physics and Astronomy, University of California
14 ALMA - Atacama Large Millimeter Array
15 MPA - Max-Planck-Institut für Astrophysik
16 INAF-Osservatorio Astronomico di Padova
17 TAU - Tel Aviv University
18 Steward Observatory, University of Arizona
19 MPIfR - Max-Planck-Institut für Radioastronomie
2 UCL - University College of London [London]
3 Rheinische Friedrich-Wilhelms-Universität Bonn
4 LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique
5 Galaxies et cosmologie
6 Observatorio Astronomico Nacional, Madrid
7 IRAM - Institut de RadioAstronomie Millimétrique
8 Department of Astronomy, University of Maryland
9 IRAP - Institut de recherche en astrophysique et planétologie
10 ETH Zürich - Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich]
11 DAPNIA - Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée
12 DAMIR/CSIC - Department of Molecular and Infrared Astrophysics, Consejo Superior de Investigaciones Científicas
13 Department of Physics and Astronomy, University of California
14 ALMA - Atacama Large Millimeter Array
15 MPA - Max-Planck-Institut für Astrophysik
16 INAF-Osservatorio Astronomico di Padova
17 TAU - Tel Aviv University
18 Steward Observatory, University of Arizona
19 MPIfR - Max-Planck-Institut für Radioastronomie
Résumé
We combine molecular gas masses inferred from CO emission in 500 star-forming galaxies (SFGs) between z = 0 and 3, from the IRAM-COLDGASS, PHIBSS1/2, and other surveys, with gas masses derived from Herschel far-IR dust measurements in 512 galaxy stacks over the same stellar mass/redshift range. We constrain the scaling relations of molecular gas depletion timescale (t depl) and gas to stellar mass ratio (M mol gas/M* ) of SFGs near the star formation "main-sequence" with redshift, specific star-formation rate (sSFR), and stellar mass (M* ). The CO- and dust-based scaling relations agree remarkably well. This suggests that the CO --> H2 mass conversion factor varies little within ±0.6 dex of the main sequence (sSFR(ms, z, M *)), and less than 0.3 dex throughout this redshift range. This study builds on and strengthens the results of earlier work. We find that t depl scales as (1 z)-0.3 × (sSFR/sSFR(ms, z, M *))-0.5, with little dependence on M *. The resulting steep redshift dependence of M mol gas/M * ≈ (1 z)3 mirrors that of the sSFR and probably reflects the gas supply rate. The decreasing gas fractions at high M* are driven by the flattening of the SFR-M * relation. Throughout the probed redshift range a combination of an increasing gas fraction and a decreasing depletion timescale causes a larger sSFR at constant M *. As a result, galaxy integrated samples of the M mol gas-SFR rate relation exhibit a super-linear slope, which increases with the range of sSFR. With these new relations it is now possible to determine M mol gas with an accuracy of ±0.1 dex in relative terms, and ±0.2 dex including systematic uncertainties.