A Huge Reservoir of Ionized Gas Around the Milky Way: Accounting for the Missing Mass?

Gupta, Anjali; Mathur, S.; Krongold, Y.; Nicastro, F.; Galeazzi, M.

doi:10.1088/2041-8205/756/1/l8

Cited by 298 publications

(416 citation statements)

References 35 publications

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“…Moreover, the preheated media at the present time implied by our model may be detected by QSO absorption line systems of highly ionized elements, such as CIV and OVI, and may indeed be the 'missing' baryons we are looking for (e.g. Yao et al 2008;Gupta et al 2012). Finally, our model suggests that the morphologies of galaxies are closely tied to the thermal state of hot halo gas and even the circum-halo medium, as it determines the angular momentum of the baryons that assembly the disk galaxies.…”

Section: Conclusion and Discussionmentioning

confidence: 94%

Formation of disc galaxies in preheated media: a preventative feedback model

Lu¹,

Mo²

2014

Monthly Notices of the Royal Astronomical Society

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We introduce a semi-analytic galaxy formation model implementing a self-consistent treatment for the hot halo gas configuration and the assembly of central disks. Using the model, we explore a preventative feedback model, in which the circum-halo medium is assumed to be preheated up to a certain entropy level by early starbursts or other processes, and compare it with an ejective feedback model, in which baryons are first accreted into dark matter halos and subsequently ejected out by feedback. The model demonstrates that when the medium is preheated to an entropy comparable to the halo virial entropy the baryon accretion can be largely reduced and delayed. In addition, the preheated medium can establish an extended low density gaseous halo when it accretes into the dark matter halos, and result in a specific angular momentum of the cooling gas large enough to form central disks as extended as those observed. Combined with simulated halo assembly histories, the preventative feedback model can reproduce remarkably well a number of observational scaling relations. These include the cold baryon (stellar plus cold gas) mass fraction-halo mass relations, star formation histories, disk size-stellar mass relation and its evolution, and the number density of low-mass galaxies as a function of redshift. In contrast, the conventional ejective feedback model fails to reproduce these observational trends. Using the model, we demonstrate that the properties of disk galaxies are closely tied to the thermal state of hot halo gas and even possibly the circum-halo medium, which suggests that observational data for the disk properties and circum-galactic hot/warm medium may jointly provide interesting constraints for galaxy formation models.

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Section: Conclusion and Discussionmentioning

confidence: 94%

Formation of disc galaxies in preheated media: a preventative feedback model

Lu¹,

Mo²

2014

Monthly Notices of the Royal Astronomical Society

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“…He notes that most local accretion may be warm rather than cool gas, although cool infalling HVCs undoubtedly are important components of local galaxy star formation (e.g., Pisano 2014). A massive (10 10 M ) hot (10 6 K) gas is indeed detected over a large region (100 kpc) around the MW (Gupta et al 2012). Part of the gas supply needed to balance the MW SFR may be due to ionized HVCs.…”

Section: Neutral Gas Observationsmentioning

confidence: 95%

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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“…Our analysis sample includes 37 known O VII absorbers at z=0 with RGS data (Fang et al 2002(Fang et al , 2006(Fang et al , 2015Nicastro et al 2002;McKernan et al 2004;Williams et al 2005Williams et al , 2006Williams et al , 2007Yao et al 2009b;Gupta et al 2012; Table 1). These include active galactic nuclei (AGNs) as well as several X-ray binaries in the Milky Way's halo and Magellanic Clouds.…”

Section: Sample and Reductionmentioning

confidence: 99%

“…They are also consistent with a spherical model. However, larger samples of absorption lines (∼40 sight lines; Bregman & LloydDavies 2007;Gupta et al 2012;Fang et al 2015) and the all-sky emission-line intensities (≈1000 sight lines Henley & Shelton 2012;Miller & Bregman 2013) favor a spherical model. Similar analyses on independent observables that also probe the hot gas, such as the pulsar dispersion measure toward the Large Magellanic Cloud and the ram-pressure stripping of Milky Way satellites favor an extended halo (Fang et al 2013;Salem et al 2015).…”

Section: Halo and Disk Modelsmentioning

confidence: 99%

The Rotation of the Hot Gas Around the Milky Way

Hodges-Kluck

Miller

Bregman

2016

ApJ

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The hot gaseous halos of galaxies likely contain a large amount of mass and are an integral part of galaxy formation and evolution. The Milky Way has a2 10 6 K halo that is detected in emission and by absorption in the O VII resonance line against bright background active galactic nuclei (AGNs), and for which the best current model is an extended spherical distribution. Using XMM-Newton Reflection Grating Spectrometer data, we measure the Doppler shifts of the O VII absorption-line centroids toward an ensemble of AGNs. These Doppler shifts constrain the dynamics of the hot halo, ruling out a stationary halo at about s 3 and a co-rotating halo at s 2 , and leading to a best-fit rotational velocity of =  f v 183 41 km s −1 for an extended halo model. These results suggest that the hot gas rotates and that it contains an amount of angular momentum comparable to that in the stellar disk. We examined the possibility of a model with a kinematically distinct disk and spherical halo. To be consistent with the emission-line X-ray data, the disk must contribute less than 10% of the column density, implying that the Doppler shifts probe motion in the extended hot halo.

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A Huge Reservoir of Ionized Gas Around the Milky Way: Accounting for the Missing Mass?

Cited by 298 publications

References 35 publications

Formation of disc galaxies in preheated media: a preventative feedback model

Formation of disc galaxies in preheated media: a preventative feedback model

Star formation sustained by gas accretion

The Rotation of the Hot Gas Around the Milky Way

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