Query : 2020A&A...643A.180H

2020A&A...643A.180H - Astronomy and Astrophysics, volume 643A, 180-180 (2020/11-1)

Scaling relations and baryonic cycling in local star-forming galaxies. II. Gas content and star-formation efficiency.


Abstract (from CDS):

Assessments of the cold-gas reservoir in galaxies are a cornerstone for understanding star-formation processes and the role of feedback and baryonic cycling in galaxy evolution. Here we exploit a sample of 392 galaxies (dubbed MAGMA, Metallicity and Gas for Mass Assembly), presented in a recent paper, to quantify molecular and atomic gas properties across a broad range in stellar mass, Mstar, from ∼107-1011M. First, we find the metallicity (Z) dependence of the conversion factor for CO luminosity to molecular H2 mass αCO to be shallower than previous estimates, with αCO ∝ (Z/Z)–1.55. Second, molecular gas mass MH2 is found to be strongly correlated with Mstar and star-formation rate (SFR), enabling predictions of MH2 good to within ∼0.2dex; analogous relations for atomic gas mass MHI and total gas mass Mgas are less accurate, ∼0.4dex and ∼0.3dex, respectively.Indeed, the behavior of atomic gas mass MHI in MAGMA scaling relations suggests that it may be a third, independent variable that encapsulates information about the circumgalactic environment and gas accretion.If Mgas is considered to depend on MHI, together with Mstar and SFR, we obtain a relation that predicts Mgas to within ∼0.05dex. Finally, the analysis of depletion times and the scaling of MHI/Mstar and MH2/Mstar over three different mass bins suggests that the partition of gas and the regulation of star formation through gas content depends on the mass regime. Dwarf galaxies (Mstar≤3x109M) tend to be overwhelmed by (HI) accretion, and despite short τH2 (and thus presumably high star-formation efficiency), star formation is unable to keep up with the gas supply. For galaxies in the intermediate Mstar "gas-equilibrium" bin (3x109M≤M_star ≤3 x 1010M), star formation proceeds apace with gas availability, and HI and H2 are both proportional to SFR.In the most massive "gas-poor, bimodality" regime (Mstar≥3x1010M), HI does not apparently participate in star formation, although it generally dominates in mass over H2. Our results confirm that atomic gas plays a key role in baryonic cycling, and is a fundamental ingredient for current and future star formation, especially in dwarf galaxies.

Abstract Copyright: © ESO 2020

Journal keyword(s): galaxies: star formation - galaxies: ISM - galaxies: fundamental parameters - galaxies: statistics - galaxies: dwarf - evolution

Simbad objects: 4

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Number of rows : 4
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
1 NGC 1569 IG 04 30 49.186 +64 50 52.52 11.72 11.86 11.03     ~ 1200 3
2 Mrk 209 bCG 12 26 16.02 +48 29 36.6   15.3       ~ 324 0
3 NGC 4423 GiG 12 27 08.972 +05 52 48.81   14.4       ~ 129 0
4 IC 4553 SyG 15 34 57.22396 +23 30 11.6084   14.76 13.88     ~ 2847 4

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