TY - JOUR
T1 - Dense Gas, Dynamical Equilibrium Pressure, and Star Formation in Nearby Star-forming Galaxies
AU - Gallagher, Molly J.
AU - Leroy, Adam K.
AU - Bigiel, Frank
AU - Cormier, Diane
AU - Jiménez-Donaire, María J.
AU - Ostriker, Eve Charis
AU - Usero, Antonio
AU - Bolatto, Alberto D.
AU - García-Burillo, Santiago
AU - Hughes, Annie
AU - Kepley, Amanda A.
AU - Krumholz, Mark
AU - Meidt, Sharon E.
AU - Meier, David S.
AU - Murphy, Eric J.
AU - Pety, Jérôme
AU - Rosolowsky, Erik
AU - Schinnerer, Eva
AU - Schruba, Andreas
AU - Walter, Fabian
N1 - Funding Information:
This paper makes use of the following ALMA data: ADS/JAO. ALMA#2013.1.00634.S and ADS/JAO.ALMA#2011.0.00004. SV. ALMA is a partnership of ESO (representing its member states), NSF (USA), and NINS (Japan), together with NRC (Canada), NSC and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO, and NAOJ. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. This work is partially based on observations carried out with the IRAM IRAM 30 m telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain). The work of M.G. and A.K.L. is partially supported by the National Science Foundation under grant nos. 1615105, 1615109, and 1653300. E.S. acknowledges financial support to the DAGAL network from the People Programme (Marie Curie Actions) of the European Union’s Seventh Frame-work Programme FP7/2007–2013/under REA grant agreement no. PITN-GA-2011-289313. A.H. acknowledges support from the Centre National d’Etudes Spatiales (CNES). A.U. acknowledges support from Spanish MINECO grants ESP2015-68964 and AYA2016-79006. E.R. is supported by a Discovery Grant from NSERC Canada. F.B. acknowledges funding from the European Unions Horizon 2020 research and innovation programme (grant agreement no. 726384—EMPIRE) This paper made use of the NASA Astrophysics Data Abstract service, AstroPy, the IDL Astronomy User’s Library, CASA, and the NASA Extragalactic Database. M.G. and A.K.L. gratefully acknowledge helpful discussions with Todd Thompson and the OSU galaxy and ISM discussion groups. Diane Cormier is supported by the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 702622. M.J.J.-D. and F.B. acknowledge support from DFG grant BI 1546/ 1-1. E.O. is supported by grant AST-7173949 from the National Science Foundation.
Publisher Copyright:
© 2018. The American Astronomical Society. All rights reserved..
PY - 2018/5/10
Y1 - 2018/5/10
N2 - We use new ALMA observations to investigate the connection between dense gas fraction, star formation rate (SFR), and local environment across the inner region of four local galaxies showing a wide range of molecular gas depletion times. We map HCN (1-0), HCO+ (1-0), CS (2-1), 13CO (1-0), and C18O (1-0) across the inner few kiloparsecs of each target. We combine these data with short-spacing information from the IRAM large program EMPIRE, archival CO maps, tracers of stellar structure and recent star formation, and recent HCN surveys by Bigiel et al. and Usero et al. We test the degree to which changes in the dense gas fraction drive changes in the SFR. (tracing the dense gas fraction) correlates strongly with I CO (tracing molecular gas surface density), stellar surface density, and dynamical equilibrium pressure, P DE. Therefore, becomes very low and HCN becomes very faint at large galactocentric radii, where ratios as low as become common. The apparent ability of dense gas to form stars, (where Σdense is traced by the HCN intensity and the star formation rate is traced by a combination of Hα and 24 μm emission), also depends on environment. decreases in regions of high gas surface density, high stellar surface density, and high P DE. Statistically, these correlations between environment and both and are stronger than that between apparent dense gas fraction () and the apparent molecular gas star formation efficiency . We show that these results are not specific to HCN.
AB - We use new ALMA observations to investigate the connection between dense gas fraction, star formation rate (SFR), and local environment across the inner region of four local galaxies showing a wide range of molecular gas depletion times. We map HCN (1-0), HCO+ (1-0), CS (2-1), 13CO (1-0), and C18O (1-0) across the inner few kiloparsecs of each target. We combine these data with short-spacing information from the IRAM large program EMPIRE, archival CO maps, tracers of stellar structure and recent star formation, and recent HCN surveys by Bigiel et al. and Usero et al. We test the degree to which changes in the dense gas fraction drive changes in the SFR. (tracing the dense gas fraction) correlates strongly with I CO (tracing molecular gas surface density), stellar surface density, and dynamical equilibrium pressure, P DE. Therefore, becomes very low and HCN becomes very faint at large galactocentric radii, where ratios as low as become common. The apparent ability of dense gas to form stars, (where Σdense is traced by the HCN intensity and the star formation rate is traced by a combination of Hα and 24 μm emission), also depends on environment. decreases in regions of high gas surface density, high stellar surface density, and high P DE. Statistically, these correlations between environment and both and are stronger than that between apparent dense gas fraction () and the apparent molecular gas star formation efficiency . We show that these results are not specific to HCN.
KW - galaxies: ISM
KW - galaxies: star formation
KW - radio lines: ISM
UR - http://www.scopus.com/inward/record.url?scp=85047213012&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85047213012&partnerID=8YFLogxK
U2 - 10.3847/1538-4357/aabad8
DO - 10.3847/1538-4357/aabad8
M3 - Article
AN - SCOPUS:85047213012
SN - 0004-637X
VL - 858
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 90
ER -