Constraints on star formation driven galaxy winds from the mass–metallicity relation at z= 0

By Molly Peeples, Francesco Shankar. 2010

183 citations recorded by the source corpus.

We extend a chemical evolution model relating galaxy stellar mass and gas-phase oxygen abundance (the mass–metallicity relation) to explicitly consider the mass-dependence of galaxy gas fractions and outflows. Using empirically derived scalings of galaxy mass with halo virial velocity in conjunction with the most recent observations of z∼ 0 total galaxy cold gas fractions and the mass–metallicity relation, we place stringent global constraints on the magnitude and scaling of the efficiency with which star-forming galaxies expel metals. We demonstrate that under the assumptions that metal accretion is negligible and the stellar initial mass function does not vary, efficient outflows are required to reproduce the mass–metallicity relation; without winds, gas-to-stellar mass ratios ≳0.3 dex higher than observed are needed. Moreover, z= 0 gas fractions are low enough that while they have some effect on the magnitude of outflows required, the slope of the gas fraction–stellar mass relation does not strongly affect our conclusions on how the wind efficiencies must scale with galaxy mass. Because theoretical descriptions of the mass loading factor , where is the mass outflow rate and is the star formation rate, are often cast in terms of the depth of the galaxy potential well, which is in turn linked to the host halo virial velocity vvir, we use one of the latest abundance matching analyses to describe outflow efficiencies in terms of vvir rather than stellar mass. Despite systematic uncertainties in the normalization and slope of the mass–metallicity relation, we show that the metal expulsion efficiency ζw≡ (Zw/Zg)ηw (where Zw is the wind metallicitiy and Zg is the interstellar medium metallicity) must be both high and scale steeply with mass. Specifically, we show that ζw≫ 1 and ζw∝v−3vir or steeper. In contrast, momentum- or energy-driven outflow models suggest that ηw should scale as v−1vir or v−2vir, respectively, implying that the Zw–M★ relation should be shallower than the Zg–M★ relation.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/d282899b06431af3208cc91ba0d7f11d9f7969e9

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Citations in the corpus

CHARACTERIZING THE CIRCUMGALACTIC MEDIUM OF NEARBY GALAXIES WITH HST/COS AND HST/STIS ABSORPTION-LINE SPECTROSCOPY (2012, background): “Molecular and atomic disk gas and dust usually are a small fraction of the total and HVCs detected in 21-cm emission are likewise a negligible amount, although the percentage of baryons in these reservoirs could be much more significant in dwarfs (Peeples & Shankar 2011).”
MaGICC discs: matching observed galaxy relationships over a wide stellar mass range (2012, background): “…no mechanism to account for the steep decrease in stellar mass of galaxies found in lower mass galaxies, even accounting C© 2012 The Authors Monthly Notices of the Royal Astronomical Society C© 2012 RAS for the fact that lower mass galaxies have higher gas contents (e.g. Peeples & Shankar 2011).”
THE MASS–METALLICITY RELATION WITH THE DIRECT METHOD ON STACKED SPECTRA OF SDSS GALAXIES (2012, methodology): “Peeples & Shankar (2011) developed an analytic model for understanding the importance of outflows in governing the MZR based on the assumption that galaxies follow zero scatter relations between stellar mass, gas fraction, metallicity, outflow efficiency, and host halo properties.”
Star formation sustained by gas accretion (2014, background): “In order to reproduce the observed mass-metallicity relationship, Davé et al. (2012) and Peeples & Shankar (2011) need w to change from 1 to 6 when M? varies from 10 11 to 109 M .”
Towards a more realistic population of bright spiral galaxies in cosmological simulations (2013, background): “Observed gas fractions in z = 0 galaxies show a clear trend of higher gas fractions at lower galaxy masses (Haynes & Giovanelli 2012, see Peeples & Shankar 2011 for a recent compilation of data).”
A model for cosmological simulations of galaxy formation physics: multi-epoch validation (2013, methodology): “We note that wind metal loadings were recently discussed in Peeples & Shankar (2011), where it was argued that winds should actually be “super-enriched” such that their metallicity should be higher than the of the surrounding ISM gas.”
Metallicity gradients in local field star-forming galaxies: insights on inflows, outflows, and the coevolution of gas, stars and metals (2015, methodology): “…is possible to put constraints on the inflow and outflow history by studying the global metallicity of star-forming galaxies using the mass-metallicity relation (e.g.,Spitoni et al. 2010; Peeples & Shankar 2011; Zahid et al. 2012; Lilly et al. 2013; Peeples et al. 2014; see alsoDavé et al. 2011a).”
The COS-Halos Survey: Metallicities in the Low-redshift Circumgalactic Medium (2017, background): “…which the CGM metallicity is higher than the metallicity derived from ionized gas within the galaxies can potentially be understood by invoking metalenriched outflows (Peeples & Shankar 2011), the median CGM metallicity is significantly lower than the ISM metallicity (Figure 10; Werk et al. 2012).”
THE UNIVERSAL RELATION OF GALACTIC CHEMICAL EVOLUTION: THE ORIGIN OF THE MASS–METALLICITY RELATION (2014, background): “A constant scale factor relates metallicity defined in terms of mass density to metallicity defined in terms of number density (Peeples & Shankar 2011).”
The role of cold gas and environment on the stellar mass-metallicity relation of nearby galaxies (2012, result): “Such behavior is not seen in our observations (see also Cortese et al. 2011), nor in those from past studies (e.g. Peeples & Shankar 2011).”
A BUDGET AND ACCOUNTING OF METALS AT z ∼ 0: RESULTS FROM THE COS-HALOS SURVEY (2013, background): “…expected to be α-enhanced (as they are presumably primarily driven by Type II supernovae, the primary sites of α-element formation), and the efficiency of such outflows in removing metals from the ISM should vary as a function of galaxy mass (e.g., Murray et al. 2005; Peeples & Shankar 2011).”
Physical Models of Galaxy Formation in a Cosmological Framework (2014, background): “Hence the MZR primarily reflects galactic outflows, modulated by wind recycling and the “metal loading factor” (Peeples & Shankar 2011).”
GAS REGULATION OF GALAXIES: THE EVOLUTION OF THE COSMIC SPECIFIC STAR FORMATION RATE, THE METALLICITY–MASS–STAR-FORMATION RATE RELATION, AND THE STELLAR CONTENT OF HALOS (2013, methodology): “Finally we note that the approach adopted here is quite similar to that taken by Peeples & Shankar (2011) who used a close analogue of Equation (27), together with observational estimates of the gas ratio µ to fit the mass-metallicity relation.”
A fundamental relation between the metallicity, gas content, and stellar mass of local galaxies (2013, background): “…for the relation have focused on explanations involving the global behaviour of gas (i.e. Audouze & Tinsley 1976), which can serve both as a pristine infalling diluent (e.g. Finlator & Davé 2008; Davé et al. 2010) and as a metal-rich outflow (Spitoni et al. 2010; Peeples & Shankar 2011).”
An origin for multiphase gas in galactic winds and haloes (2015, background): “…al. 1990), helping to regulate star formation, shaping the stellar mass function and the massmetallicity relation (Dekel & Silk 1986; Finlator & Davé 2008; Erb 2008; Peeples & Shankar 2011), and enriching the intergalactic medium with metals (Aguirre et al. 2001; Oppenheimer & Davé 2006, 2008).”