EVIDENCE FOR COLD ACCRETION: PRIMITIVE GAS FLOWING ONTO A GALAXY AT<i>z</i>∼ 0.274

Ribaudo, Joseph; Lehner, N.; Howk, J. C.; Werk, Jessica K.; Tripp, Todd M.; Prochaska, J. Xavier; Meiring, Joseph D.; Tumlinson, Jason

doi:10.1088/0004-637x/743/2/207

Cited by 123 publications

(156 citation statements)

References 54 publications

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“…Welty et al 1999). This systematic uncertainty is, however, not restricted to HVCs but is relevant also for the analysis of intervening metal absorbers at low z using UV data with limited S/N and spectral resolution (e.g., Ribaudo et al 2011). For the Voigt profile fitting presented in this paper our strategy was to find the minimum number of velocity components (Voigt components) that are required to obtain a satisfying fit to the STIS HVC absoption profiles.…”

Section: Data Aquisition and Analysis Methodsmentioning

confidence: 99%

The Milky Way halo as a QSO absorption-line system

Herenz¹,

Richter²,

Charlton³

et al. 2013

A&A

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We use archival UV absorption-line data from HST/STIS to statistically analyse the absorption characteristics of the high-velocity clouds (HVCs) in the Galactic halo towards more than 40 extragalactic background sources. We determine absorption covering fractions of low-and intermediate ions (O i, C ii, Si ii, Mg ii, Fe ii, Si iii, C iv, and Si iv) in the range f c = 0.20−0.70. For detailed analysis we concentrate on Si ii absorption components in HVCs, for which we investigate the distribution of column densities, b-values, and radial velocities. Combining information for Si ii and Mg ii, and using a geometrical HVC model we investigate the contribution of HVCs to the absorption cross section of strong Mg ii absorbers in the local Universe. We estimate that the Galactic HVCs would contribute on average ∼52 percent to the total strong Mg ii cross section of the Milky Way, if our Galaxy were to be observed from an exterior vantage point. We further estimate that the mean projected covering fraction of strong Mg ii absorption in the Milky Way halo and disc from an exterior vantage point is f c,sMgII = 0.31 for a halo radius of R = 61 kpc. These numbers, together with the observed number density of strong Mg ii absorbers at low redshift, indicate that the contribution of infalling gas clouds (i.e., HVC analogues) in the halos of Milky Way-type galaxies to the cross section of strong Mg ii absorbers is < 34 percent.These findings are in line with the idea that outflowing gas (e.g., produced by galactic winds) in the halos of more actively star-forming galaxies dominate the absorption-cross section of strong Mg ii absorbers in the local Universe.

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Section: Data Aquisition and Analysis Methodsmentioning

confidence: 99%

The Milky Way halo as a QSO absorption-line system

Herenz¹,

Richter²,

Charlton³

et al. 2013

A&A

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“…A similarly weak evolution with redshift of the metal content of the IGM had been noted by Pettini et al (2003, see also Ryan-Weber et al 2009), who speculated that the observed metals were created by the sources responsible for the re-ionization of the universe or, alternatively, by outflows from star forming galaxies at later times. Ribaudo et al (2011) reported a LLS at z = 0.3 with very low-metallicity gas at 37 kpc from a near solar-metallicity 0.3 L star-forming galaxy. This was taken as proof of gas infalling onto the galaxy (see the discussion in Sect.…”

Section: The Role Of Mergersmentioning

confidence: 99%

Star formation sustained by gas accretion

Alméida

Elmegreen

Muñoz–Tuñón

et al. 2014

Astron Astrophys Rev

183

130

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Numerical simulations predict that metal-poor gas accretion from the cosmic web fuels the formation of disk galaxies. This paper discusses how cosmic gas accretion controls star formation, and summarizes the physical properties expected for the cosmic gas accreted by galaxies. The paper also collects observational evidence for gas accretion sustaining star formation. It reviews evidence inferred from neutral and ionized hydrogen, as well as from stars. A number of properties characterizing large samples of star-forming galaxies can be explained by metal-poor gas accretion, in particular, the relationship among stellar mass, metallicity, and star-formation rate (the so-called fundamental metallicity relationship). They are put forward and analyzed. Theory predicts gas accretion to be particularly important at high redshift, so indications based on distant objects are reviewed, including the global star-formation history of the universe, and the gas around galaxies as inferred from absorption features in the spectra of background sources.

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“…However, even when a hot isotropic atmosphere is present around a galaxy, some residual cold accretion can exist, in particular for massive halos at high redshifts (e.g. Thom et al 2011;Ribaudo et al 2011). The recent works of Nelson et al 2013, based on a new generation of hydrodynamic codes, call into question this bimodal accretion scenario.…”

Section: Introductionmentioning

confidence: 99%

“…Observations (e.g. Thom et al 2011;Ribaudo et al 2011;Crighton et al 2013) and simulations (e.g. Fumagalli et al 2011) indicate that the two accretion modes are associated with different metallicity contents.…”

Section: Introductionmentioning

confidence: 99%

Metal enrichment in a semi-analytical model, fundamental scaling relations, and the case of Milky Way galaxies

Cousin

Buat

Boissier

et al. 2016

A&A

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Context. Gas flows play a fundamental role in galaxy formation and evolution, providing the fuel for the star formation process. These mechanisms leave an imprint in the amount of heavy elements that enrich the interstellar medium. Thus, the analysis of this metallicity signature provides additional constraint on the galaxy formation scenario. Aims. We aim to discriminate between four different galaxy formation models based on two accretion scenarios and two different star formation recipes. We address the impact of a bimodal accretion scenario and a strongly regulated star formation recipe on the metal enrichment process of galaxies. Methods. We present a new extension of the eGalICS model, which allows us to track the metal enrichment process in both stellar populations and in the gas phase. Based on stellar metallicity bins from 0 to 2.5 Z , our new chemodynamical model is applicable for situations ranging from metal-free primordial accretion to very enriched interstellar gas contents. We use this new tool to predict the metallicity evolution of both the stellar populations and gas phase. We compare these predictions with recent observational measurements. We also address the evolution of the gas metallicity with the star formation rate (SFR). We then focus on a subsample of Milky Way-like galaxies. We compare both the cosmic stellar mass assembly and the metal enrichment process of such galaxies with observations and detailed chemical evolution models. Results. Our models, based on a strong star formation regulation, allow us to reproduce well the stellar mass to gas-phase metallicity relation observed in the local Universe. The shape of our average stellar mass to stellar metallicity relations is in good agreement with observations. However, we observe a systematic shift towards high masses. Our M −Z g −SFR relation is in good agreement with recent measurements: our best model predicts a clear dependence with the SFR. Both SFR and metal enrichment histories of our Milky Way-like galaxies are consistent with observational measurements and detailed chemical evolution models. We finally show that Milky Way progenitors start their evolution below the observed main sequence and progressively reach this observed relation at z 0.

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EVIDENCE FOR COLD ACCRETION: PRIMITIVE GAS FLOWING ONTO A GALAXY ATz∼ 0.274

Cited by 123 publications

References 54 publications

The Milky Way halo as a QSO absorption-line system

The Milky Way halo as a QSO absorption-line system

Star formation sustained by gas accretion

Metal enrichment in a semi-analytical model, fundamental scaling relations, and the case of Milky Way galaxies

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