The EDGE─CALIFA Survey: Variations in the Molecular Gas Depletion Time in Local Galaxies

DOI: 
10.3847/1538-4357/aa88c0
Publication date: 
01/11/2017
Main author: 
Utomo, Dyas
IAA authors: 
Garcia-Benito, Ruben
Authors: 
Utomo, Dyas;Bolatto, Alberto D.;Wong, Tony;Ostriker, Eve C.;Blitz, Leo;Sanchez, Sebastian F.;Colombo, Dario;Leroy, Adam K.;Cao, Yixian;Dannerbauer, Helmut;Garcia-Benito, Ruben;Husemann, Bernd;Kalinova, Veselina;Levy, Rebecca C.;Mast, Damian;Rosolowsky, Erik;Vogel, Stuart N.
Journal: 
The Astrophysical Journal
Refereed: 
Yes
Publication type: 
Article
Volume: 
849
Pages: 
26
Abstract: 

We present results from the EDGE survey, a spatially resolved CO(1−0) follow-up to CALIFA, an optical Integral Field Unit survey of local galaxies. By combining the data products of EDGE and CALIFA, we study the variation in molecular gas depletion time (τ <SUB>dep</SUB>) on kiloparsec scales in 52 galaxies. We divide each galaxy into two parts: the center, defined as the region within 0.1 {R}<SUB>25</SUB>, and the disk, defined as the region between 0.1 and 0.7 {R}<SUB>25</SUB>. We find that 14 galaxies show a shorter τ <SUB>dep</SUB> (∼1 Gyr) in the center relative to that in the disk (τ <SUB>dep</SUB> ∼ 2.4 Gyr), 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 <SUB>dep</SUB> resemble the intermediate regime between galactic disks and starburst galaxies. Furthermore, the central drop in τ <SUB>dep</SUB> is correlated with a central increase in the stellar surface density, suggesting that a shorter τ <SUB>dep</SUB> is associated with molecular gas compression by the stellar gravitational potential. We argue that varying the CO-to-H<SUB>2</SUB> conversion factor only exaggerates the central drop of τ <SUB>dep</SUB>.

Database: 
ADS
URL: 
https://ui.adsabs.harvard.edu/#abs/2017ApJ...849...26U/abstract
ADS Bibcode: 
2017ApJ...849...26U
Keywords: 
galaxies: star formation;galaxies: structure;ISM: abundances;ISM: molecules