Constraint on the inflow/outflow rates in star-forming galaxies at z ∼ 1.4 from molecular gas observations

Journal article

We constrain the rate of gas inflow into and outflow from a main-sequence star-forming galaxy at z ∼ 1.4 by fitting a simple analytic model for the chemical evolution in a galaxy to the observational data of the stellar mass, metallicity, and molecular gas mass fraction. The molecular gas mass is derived from CO observations with a metallicity-dependent CO-to-H 2 conversion factor, and the gas metallicity is derived from the Hα and [N II]λ 6584 emission line ratio. Using a stacking analysis of CO integrated intensity maps and the emission lines of Hα and [N II] , the relation between stellar mass, metallicity, and gas mass fraction is derived. We constrain the inflow and outflow rates with least-chi-square fitting of a simple analytic chemical evolution model to the observational data. The best-fit inflow and outflow rates are ∼1.7 and ∼0.4 in units of star formation rate (SFR), respectively. The inflow rate is roughly comparable to the sum of the SFR and outflow rate, which supports the equilibrium model for galaxy evolution; i.e., all inflow gas is consumed by star formation and outflow.

Authors: Seko, A; Ohta, K; Yabe, K; Hatsukade, B; Akiyama, M

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Astronomical Societ
• Journal: Astrophysical Journal
• Volume: 833
• Issue: 1
• Pages: 53-53
• Publication date: 2016-12-10
• Acceptance date: 2016-10-09
• DOI: 10.3847/1538-4357/833/1/53
• EISSN: 1538-4357
• ISSN: 0004-637X
• Keywords: galaxies: ISM; galaxies: evolution