CONSTRAINT on the INFLOW/OUTFLOW RATES in STAR-FORMING GALAXIES at z ∼ 1.4 from MOLECULAR GAS OBSERVATIONS

Akifumi Seko, Kouji Ohta, Kiyoto Yabe, Bunyo Hatsukade, Masayuki Akiyama, Naoyuki Tamura, Fumihide Iwamuro, Gavin Dalton

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

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-H2 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.

Original languageEnglish
Article number53
JournalAstrophysical Journal
Volume833
Issue number1
DOIs
Publication statusPublished - 2016 Dec 10

Keywords

  • galaxies: ISM
  • galaxies: evolution

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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