The EDGE-CALIFA survey: Variations in the Molecular Gas Depletion Time in Local Galaxies

Dyas Utomo; Alberto D. Bolatto; Tony Wong; Eve C. Ostriker; Leo Blitz; Sebastian F. Sanchez; Dario Colombo; Adam K. Leroy; Yixian Cao; Helmut Dannerbauer; Ruben Garcia-Benito; Bernd Husemann; Veselina Kalinova; Rebecca C. Levy; Damian Mast; Erik Rosolowsky; Stuart N. Vogel

doi:10.3847/1538-4357/aa88c0

paper

The EDGE-CALIFA survey: Variations in the Molecular Gas Depletion Time in Local Galaxies

arXiv:1704.03481 · doi:10.3847/1538-4357/aa88c0

Abstract

We present results from the EDGE survey, a spatially resolved CO(1-0) follow-up to CALIFA, an optical Integral Field Unit (IFU) survey of local galaxies. By combining the data products of EDGE and CALIFA, we study the variation in molecular gas depletion time ( $τ_{dep}$ ) on kiloparsec scales in 52 galaxies. We divide each galaxy into two parts: the center, defined as the region within $0.1 R_{25}$ , and the disk, defined as the region between $0.1$ and $0.7 R_{25}$ . We find that 14 galaxies show a shorter $τ_{dep}$ ( $\sim 1$ Gyr) in the center relative to that in the disk ( $τ_{dep} \sim 2.4$ Gyrs), which means the central region in those galaxies is more efficient at forming stars per unit molecular gas mass. This finding implies that the centers with shorter $τ_{dep}$ resemble the intermediate regime between galactic disks and starburst galaxies. Furthermore, the central drop in $τ_{dep}$ is correlated with a central increase in the stellar surface density, suggesting that a shorter $τ_{dep}$ is associated with molecular gas compression by the stellar gravitational potential. We argue that varying the CO-to-H $_{2}$ conversion factor only exaggerates the central drop of $τ_{dep}$ .

17 pages, accepted in ApJ on Aug 24, 2017

The EDGE-CALIFA survey: Variations in the Molecular Gas Depletion Time in Local Galaxies

Abstract

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