The Metallicity of Galaxy Disks: Infall versus Outflow

By J. J. Dalcanton. 2006

191 citations recorded by the source corpus.

Both gas accretion (infall) and winds (outflow) change a galaxy's metallicity and gas fraction, lowering the effective yield. Low effective yields in galaxies with rotation speeds <120 km s-1 have been widely interpreted as due to the onset of supernova-driven winds below a characteristic galaxy mass, but gas accretion is also a viable explanation. However, calculations presented here prove that (1) metal-enriched outflows are the only mechanism that can significantly reduce the effective yield, but only for gas-rich systems; (2) it is nearly impossible to reduce the effective yield of a gas-poor system, no matter how much gas is lost or accreted; and (3) any subsequent star formation drives the effective yield back to the closed-box value. Thus, only gas-rich systems with low star formation rates (such as dwarf irregulars) can produce and maintain low effective yields. The drop in effective yield seen in low-mass galaxies is therefore due to these galaxies' gas richnesses and low star formation rates, which result from their surface densities falling entirely below the Kennicutt SF threshold. Additional calculations confirm that the fraction of baryonic mass lost through winds varies only weakly with galaxy mass, shows no sharp upturn at any mass scale, and does not require that >15% of the baryons have been lost by galaxies of any mass. Supernova feedback is therefore unlikely to be effective for removing large amounts of gas from low-mass disk galaxies. In addition, the dependence between metal loss and galaxy mass is sufficiently weak that massive galaxies dominate metal enrichment of the IGM. The calculations in this paper provide limiting cases for any arbitrary chemical evolution history, as is proven in an Appendix.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/1c741b5aec65f2d9c0f28dda40372f11271efb06

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In Astronomy and Astrophysics

1. P. Hopkins
2. R. Dav'e
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4. R. Somerville
5. R. Maiolino
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In Instrumentation

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5. Simon D. M. White
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7. M. Blanton
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Citations in the corpus

• The role of cold gas and environment on the stellar mass-metallicity relation of nearby galaxies (2012, methodology): “Firstly, most previous studies have lacked spatially integrated, drift-scan spectra for a moderately-sized galaxy sample, instead using SDSS fiber spectroscopy or standard longslit spectroscopy (see e.g. Garnett 2002; Tremonti et al. 2004; Dalcanton 2007).”
• Constraints on star formation driven galaxy winds from the mass–metallicity relation at z= 0 (2010, background): “The wind metallicity is thus Zw = (1− fe)Zej,max + feZg, (14) where we note thatfe may vary with galaxy mass and must satisfy 0 6 fe 1.”
• Physical properties and environments of nearby galaxies (2009, background): “However, a detailed analysis by Dalcanton (2007) demonstrates that inflow of pristine gas can only reduce yeff by a limited amount (30%–50% for reasonably gas-rich galaxies) and cannot explain the observed trends.”
• A BUDGET AND ACCOUNTING OF METALS AT z ∼ 0: RESULTS FROM THE COS-HALOS SURVEY (2013, background): “…highly efficient winds that remove large amounts of freshly produced metals are necessary to understand the ISM abundances of both local and high-redshift galaxies (e.g., Dalcanton 2007; Erb 2008; Finlator & Davé 2008; Arrigoni 2010; Peeples & Shankar 2011; Davé et al. 2011; Dayal et al. 2013).”
• DIRECT OXYGEN ABUNDANCES FOR LOW-LUMINOSITY LVL GALAXIES (2012, background): “However, Dalcanton (2007) emphasizes the importance of star formation efficiency as outflows are an insufficient regulator in the absence of depressed star formation.”
• De re metallica: the cosmic chemical evolution of galaxies (2018, background): “The effective yields are a way to measure the influence of infall and outflows on the chemical evolution of a galaxy (Matteucci, 2001; Garnett, 2002; Dalcanton, 2007).”
• The Evolution of the Intergalactic Medium (2015, background): “Observationally, galactic disks contain only a fraction of the metals synthesized by their stars (e.g. Dalcanton 2007; Davé, Finlator & Oppenheimer 2011), with the fraction of metals retained in a galaxy’s ISM estimated to be ∼ 20% across a large range of stellar masses at z ∼ 0 (with an uncertain…”
• THREE-DIMENSIONAL INTEGRAL FIELD OBSERVATIONS OF 10 GALACTIC WINDS. I. EXTENDED PHASE (≳10 Myr) OF MASS/ENERGY INJECTION BEFORE THE WIND BLOWS (2010, background): “…manage to retain a large fraction of their metals, in contrast to lower mass galaxies where metal loss appears to be anticorrelated with baryonic mass. Recent theoretical work has shown that a low-metal content in dwarf galaxies is attributable to efficient metal-enriched outflows (Dalcanton 2007).”
• GAS-PHASE OXYGEN GRADIENTS IN STRONGLY INTERACTING GALAXIES. I. EARLY-STAGE INTERACTIONS (2010, background): “Intense study of the mass-metallicity (hereafter, M − Z) relation in recent years has yet to pin down its origin (e.g., Tremonti et al. 2004; Köppen et al. 2007; Brooks et al. 2007; Dalcanton 2007; Zahid et al. 2010).”
• LSD: Lyman-break galaxies Stellar populations and Dynamics – I. Mass, metallicity and gas at z∼ 3.1 (2009, background): “In all cases, yeff must be smaller than y, as discussed, for example, by Edmunds (1990) and Dalcanton (2007).”
• 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, background): “…have included differing star-formation efficiencies within galaxies (e.g. Brooks et al 2007, Mouhcine et al 2008, Calura et al., 2009), supernova-driven winds (e.g. Larson 1974, T+04, Dalcanton, 2007, Finlator & Davé 2008), and variations in the initial mass function of stars (Köppen et al 2007).”
• Cold gas properties of the Herschel Reference Survey - II. Molecular and total gas scaling relations (2014, background): “The relationship between the total gas-to-stellar mass r tio vs. metallicity, for instance, is a well known relation expected for the chemical evolution of galaxies (Searle & Sargent 1972, Edmunds 1990, Garnett 2002, Dalcanton 2007).”
• Clues to the Origin of the Mass-Metallicity Relation: Dependence on Star Formation Rate and Galaxy Size (2007, methodology): “However, Dalcanton (2007) has used an analytic model of gas infall/outflow to show that even a modest amount of star formation following metal loss through winds quickly erases the signature of such an event.”
• ABSORPTION-LINE PROBES OF THE PREVALENCE AND PROPERTIES OF OUTFLOWS IN PRESENT-DAY STAR-FORMING GALAXIES (2010, background): “The massmetallicity and effective yield relations observed in local galaxies suggest that galactic winds transport highly metalenriched gas out of galaxies and into the IGM (e.g., Garnett 2002; Tremonti et al. 2004; Dalcanton 2007).”
• On the galaxy stellar mass function, the mass-metallicity relation, and the implied baryonic mass function (2008, background): “If there are continuing infalls and outflows (e.g. Dalcanton 2007; Erb 2008), the case is less clear because of the dependence on the metallicity of the infalling gas.”