The chemical evolution of local star-forming galaxies: radial profiles of ISM metallicity, gas mass, and stellar mass and constraints on galactic accretion and winds

Abstract

The radially averaged metallicity distribution of the ISM and the young stellar population of a sample of 20 disk galaxies is investigated by means of an analytical chemical evolution model which assumes constant ratios of galactic wind mass loss and accretion mass gain to star formation rate. Based on this model the observed metallicities and their gradients can be described surprisingly well by the radially averaged distribution of the ratio of stellar mass to ISM gas mass. The comparison between observed and model predicted metallicity is used to constrain the rate of mass loss through galactic wind and accretion gain in units of the star formation rate. Three groups of galaxies are found: galaxies with either mostly winds and only weak accretion, or mostly accretion and only weak winds, and galaxies where winds are roughly balanced by accretion. The three groups are distinct in the properties of their gas disks.Galaxies with approximately equal rates of mass-loss and accretion gain have low metallicity, atomic hydrogen dominated gas disks with a flat spatial profile. The other two groups have gas disks dominated by molecular hydrogen out to 0.5 to 0.7 isophotal radii and show a radial exponential decline, which is on average steeper for the galaxies with small accretion rates. The rates of accretion ( 1.0 × SFR) and outflow ( 2.4 × SFR) are relatively low. The latter depend on the calibration of the zero point of the metallicity determination from the use of HII region strong emission lines.

Characterization of star-forming dwarf galaxies at 0.1 ≲z ≲ 0.9 in VUDS: probing the low-mass end of the mass-metallicity relation

“…We adopt the general solution for these simple models derived by Kudritzki et al (2015) (hereafter K15) and relating the oxygen mass fraction O m (defined as the mass fraction of oxygen in the ISM: O m = M O /M gas ) and the gas fraction f gas :…”

Red Supergiant Stars as Cosmic Abundance Probes: Kmos Observations in NGC 6822

“…According to Kudritzki et al (2015), the ratio y/(1 − R) can be empirically determined from the fact that the metallicity of the young stellar population in the solar neighborhood is solar, with a mass fraction Z e = 0.014 (Nieva & Przybilla 2012). With a stellar-to-gas mass column density of 4.48 in the solar neighborhood (Wolfire et al 2003;Bovy & Rix 2013) one then obtains y/(1 − R) = 0.0082 = 0.59 Z e with an uncertainty of 15% dominated by the 0.05 dex uncertainty of the metallicity determination of the young population.…”

On the Effective Oxygen Yield in the Disks of Spiral Galaxies

“…The latter manifests itself as the flattening of the (O/H) gradient at large radial distances R, mostly observed in galaxies which experience or have experienced a strong interaction (Werk, Putman, Meurer et al 2011;Zasov, Saburova, Katkov et al 2015). A comparison of y ef f and y o has been used by different authors to clarify the degree of difference of evolution from the closed-box model and to specify the processes which are responsible for the metal abundance besides the star formation and gas consumption (see f.e, Zahid, Dima, Kudritzki et al 2014;Kudritzki, Ho, Schruba et al 2015;Ascasibar, Gavilán, Pinto et al 2015).…”

“…Note, however, that the accretion and wind can in principle be disentangled (see Kudritzki, Ho, Schruba et al 2015). Although the results remain model dependent Kudritzki, Ho, Schruba et al (2015) demonstrated that the role of gas inflow/outflow may be different for different spiral galaxies.…”

“…Pilyugin, Thuan, & Vílchez 2007;Dalcanton 2007;Spitoni, Calura, Matteucci et al 2010;Zahid, Dima, Kudritzki et al 2014;Ascasibar, Gavilán, Pinto et al 2015;Kudritzki, Ho, Schruba et al 2015;Lu, Mo, & Wechsler 2015).…”