Hot Gas Halos Around Disk Galaxies: Confronting Cosmological Simulations With Observations

Rasmussen, Jesper; Sommer–Larsen, Jesper; Pedersen, K.; Toft, Sune; Benson, Andrew; Bower, Richard G.; Grove, L. F.

doi:10.1088/0004-637x/697/1/79

Cited by 99 publications

(131 citation statements)

References 90 publications

(183 reference statements)

Supporting

Mentioning

121

Contrasting

Order By: Relevance

“…3,4]. As the hot gas of these more massive systems, the coronal gas is unlikely to fragment into clouds via thermal instability [5], but it is expected to cool monolithically and feed the central black hole rather than produce an extended cold disc in which stars can form.…”

Section: The Proposed Scenariomentioning

confidence: 99%

Galactic Fountains and Gas Accretion

Marinacci

Binney

Fraternali

et al. 2010

AIP Conference Proceedings

109

168

View full text Add to dashboard Cite

Abstract. Star-forming disc galaxies such as the Milky Way need to accrete > ∼ 1 M ⊙ of gas each year to sustain their star formation. This gas accretion is likely to come from the cooling of the hot corona, however it is still not clear how this process can take place. We present simulations supporting the idea that this cooling and the subsequent accretion are caused by the passage of cold galactic-fountain clouds through the hot corona. The Kelvin-Helmholtz instability strips gas from these clouds and the stripped gas causes coronal gas to condense in the cloud's wake. For likely parameters of the Galactic corona and of typical fountain clouds we obtain a global accretion rate of the order of that required to feed the star formation.Keywords: turbulence -ISM: kinematics and dynamics -Galaxy: kinematics and dynamics -Galaxy: structure -galaxies: formation PACS: 98.35.Ac, 98.38.Am, 98.58.Ay, 98.62.Ai THE PROPOSED SCENARIOStar-forming disc galaxies like the Milky Way must accrete > ∼ 1 M ⊙ of fresh gas each year [see 1, and references therein] and have built their discs gradually over the last 10 Gyr [e.g. 2]. A central question is the origin of the accreted gas and how this gas reaches the thin disc whitin which the process of star formation takes place. The virial-temperature corona, in which disc galaxies are embedded, is the only reservoir of baryons capable of sustaining an accretion rate of ∼ 1 M ⊙ yr −1 for a Hubble time. We present the results of a set of grid-based hydrodynamical simulations supporting the idea that the gas needed by the disc to form stars is drawn from this corona.Coronae of disc galaxies are similar in many respects to the hot atmospheres of giant elliptical galaxies and galaxy clusters, but with lower gas temperature and density [e.g. 3, 4]. As the hot gas of these more massive systems, the coronal gas is unlikely to fragment into clouds via thermal instability [5], but it is expected to cool monolithically and feed the central black hole rather than produce an extended cold disc in which stars can form. However, if the gas needed to feed star formation has to be drawn from the corona, a mechanism that makes the hot gas accrete onto the disc must be at work.There is abundant evidence that star formation in galaxies like the Milky Way powers a galactic fountain: ejection of gas from the mid-plane by supernova explosions [6]. Through the fountain a significant fraction (from 10 to 25 %) of the whole HI content of the galaxy is carried into its halo [see 7, and references therein]. In this work, supported by several lines of argument, we hypothesise that the transfer of gas from the corona to the star-forming disc is effected by the HI clouds ejected by the galactic fountain [8].Our hydrodynamical simulations suggest that the gas accretion proceeds through the following steps: (i) stripping of gas from fountain clouds by the corona as a result of the Kelvin-Helmholtz instability, (ii) mixing of the (high metallicity) stripped gas with a comparable amount of coronal gas in the turbulent ...

show abstract

Section: The Proposed Scenariomentioning

confidence: 99%

Galactic Fountains and Gas Accretion

Marinacci

Binney

Fraternali

et al. 2010

AIP Conference Proceedings

109

168

View full text Add to dashboard Cite

show abstract

“…Such hot galactic coronae are predicted to arise by shock heating of gas falling into potential wells (hot-mode accretion; Rees & Ostriker 1977;Birnboim & Dekel 2003;Kereš et al 2005Kereš et al , 2009, and by feedback from stellar activity (supernovae) within the galaxies themselves (e.g. Rasmussen et al 2009;Crain et al 2010;Henley et al 2010). If this boundary layer scenario is correct, then the larger significance of O vi observations in DLAs at z = 2-3 would then be that feedback and/or hot-mode accretion are already active at this epoch and have created hot galactic coronae.…”

Section: Collisional Ionization Modelsmentioning

confidence: 99%

High-ion absorption in the proximate damped Ly-αsystem toward Q0841+129

Ledoux¹,

Petitjean²,

Srianand³

et al. 2011

A&A

View full text Add to dashboard Cite

We present VLT/UVES spectroscopy of the quasar Q0841+129, whose spectrum shows a proximate damped Ly-α (PDLA) absorber at z = 2.47621 and a proximate sub-DLA at z = 2.50620, both lying close in redshift to the QSO itself at z em = 2.49510 ± 0.00003. This fortuitous arrangement, with the sub-DLA acting as a filter that hardens the QSO's ionizing radiation field, allows us to model the ionization level in the foreground PDLA, and provides an interesting case-study on the origin of the high-ion absorption lines Si iv, C iv, and O vi in DLAs. The high ions in the PDLA show at least five components spanning a total velocity extent of ≈160 km s −1 , whereas the low ions exist predominantly in a single component spanning just 30 km s −1 . We examine various models for the origin of the high ions. Both photoionization and turbulent mixing layer models are fairly successful at reproducing the observed ionic ratios after correcting for the non-solar relative abundance pattern, though neither model can explain all five components. We show that the turbulent mixing layer model, in which the high ions trace the interfaces between the cool PDLA gas and a hotter phase of shock-heated plasma, can explain the average high-ion ratios measured in a larger sample of 12 DLAs.

show abstract

“…Anderson & Bregman 2010). Simulations and semi-analytic models each predict that the circum-galactic halo should extend out to the virial radius, and contains a large fraction or most of the socalled missing baryons (Toft et al 2002;Maller & Bullock 2004;Sommer-Larsen 2006;Rasmussen et al 2009;Crain et al 2010;Gnedin 2012).…”

Section: Introductionmentioning

confidence: 99%

Circum-Galactic Gas and the Isotropic Gamma-Ray Background

Feldmann

Hooper

Gnedin

2012

ApJ

101

View full text Add to dashboard Cite

Interactions of cosmic rays with the interstellar medium in the disk of the Milky Way provide the majority of the diffuse gamma-ray emission observed by the Fermi Gamma-ray Space Telescope. In addition to the gas which is densely concentrated along the galactic plane, hydrodynamical simulations and observational evidence favor the presence of a halo of hot (T ∼ 10 6 K) ionized hydrogen (H ii), extending with non-negligible densities out to the virial radius of the Milky Way. We show that cosmic-ray collisions with this circum-galactic gas should be expected to provide on the order of 3%-10% of the observed isotopic gamma-ray background at energies above 1 GeV. In addition, gamma rays originating from the extended H ii halos of other galaxies along a given line of sight should contribute at a similar level.

show abstract

Hot Gas Halos Around Disk Galaxies: Confronting Cosmological Simulations With Observations

Cited by 99 publications

References 90 publications

Galactic Fountains and Gas Accretion

Galactic Fountains and Gas Accretion

High-ion absorption in the proximate damped Ly-αsystem toward Q0841+129

Circum-Galactic Gas and the Isotropic Gamma-Ray Background

Contact Info

Product

Resources

About