COMBINED CO AND DUST SCALING RELATIONS OF DEPLETION TIME AND MOLECULAR GAS FRACTIONS WITH COSMIC TIME, SPECIFIC STAR-FORMATION RATE, AND STELLAR MASS

By R. Genzel, L. Tacconi, D. Lutz, A. Saintonge, S. Berta, B. Magnelli, F. Combes, S. García-Burillo, R. Neri, A. Bolatto and 26 more. 2014

385 citations recorded by the source corpus.

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 (tdepl) and gas to stellar mass ratio (Mmol 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 tdepl scales as (1 + z)−0.3 × (sSFR/sSFR(ms, z, M*))−0.5, with little dependence on M*. The resulting steep redshift dependence of Mmol 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 Mmol 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 Mmol gas with an accuracy of ±0.1 dex in relative terms, and ±0.2 dex including systematic uncertainties.

Subfields: Astronomy and Astrophysics, Spectroscopy

View Paper: https://www.semanticscholar.org/paper/705d4185e79c74e9ffea97dad52eb99057cbd1e4

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In Astronomy and Astrophysics

1. P. Hopkins
2. A. Dekel
3. L. Hernquist
4. R. Dav'e
5. P. V. van Dokkum
6. R. Somerville
7. T. Naab
8. M. Franx

In Spectroscopy

1. Mark R. Krumholz
2. F. Walter
3. A. Dekel
4. S. Lilly
5. D. Ceverino
6. R. Genzel
7. L. Tacconi
8. A. Sternberg

Citations in the corpus

• A unified model for galactic discs: star formation, turbulence driving, and mass transport (2017, background): “…et al. 2013, 2015; Meidt et al. 2013; Pety et al. 2013), or the recombination lines of ionized gas (Cresci et al. 2009; Lehnert et al. 2009, 2013; Green et al. 2010, 2014; Le Tiran et al. 2011; Swinbank et al. 2012; Arribas et al. 2014; Genzel et al. 2014; Moiseev, Tikhonov & Klypin 2015).”
• AGN wind scaling relations and the co-evolution of black holes and galaxies (2017, background): “Genzel et al. (2014) use 〈ne〉 = 80 cm−3 because this is the mean value in the disks and centres of star-forming galaxies.”
• Evolution of density profiles in high-z galaxies: compaction and quenching inside-out (2015, methodology): “In addition, the bulge has grown, so the remaining disc is stable gravitationally (morphological quenching, see Martig et al. 2009; Genzel et al. 2014; Tacchella et al. 2015b) and does not drive more gas inward.”
• xCOLD GASS: The Complete IRAM 30 m Legacy Survey of Molecular Gas for Galaxy Evolution Studies (2017, background): “…an ideal z = 0 reference point for studies of molecular gas at higher redshifts (e.g. Combes et al. 2013; Troncoso et al. 2014; Seko et al. 2016; Genzel et al. 2015; Tacconi et al. 2017), and provides powerful constraints for theoretical models and numerical simulations (e.g. Lagos et al. 2011;…”
• CO excitation of normal star forming galaxies out to $z=1.5$ as regulated by the properties of their interstellar medium (2014, background): “…de Bure interferometer (Daddi et al 2008; 2010a; D10 hereafter; Tacconi et al 2010; 2013; Geach et al 2011) and confirmed by gas mass estimates obtained via the conversion of dust masses (Magdis et al 2011; 2012; Santini et al 2014; Scoville et al 2014; Magnelli et al 2013; Genzel et al 2014).”
• The confinement of star-forming galaxies into a main sequence through episodes of gas compaction, depletion and replenishment (2015, background): “…as observed by Cicone et al. (2016), combined with the suppression of gas inflow into the centre because the gas disc has shrunk and (at least temporarily) disappeared, or became gravitationally stable (morphological quenching, Martig et al. 2009; Genzel et al. 2014; Tacchella et al. 2015b).”
• The SINS/zC-SINF Survey of z ∼ 2 Galaxy Kinematics: SINFONI Adaptive Optics–assisted Data and Kiloparsec-scale Emission-line Properties (2018, methodology): “This object has by far the largest nuclear Fbroad/Fnarrow ratio (∼ 3), such that narrower line emission that would trace star formation around the center is comparatively very weak (Förster Schreiber et al. 2014; Genzel et al. 2014a).”
• FORMING COMPACT MASSIVE GALAXIES (2015, background): “Such winds can be driven by star formation (e.g., Heckman, Armus, & Miley 1987) and/or AGNs (e.g., Proga, Stone, & Kallman 2000) and are ubiquitous in star forming galaxies at high redshifts (Franx et al. 1997; Pettini et al. 1998; Förster Schreiber et al. 2014; Genzel et al. 2014a).”