Circumgalactic Oxygen Absorption and Feedback

Mathews, William G.; Prochaska, J. Xavier

doi:10.3847/2041-8213/aa8861

Cited by 50 publications

(49 citation statements)

References 30 publications

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“…Alternative versions of the halo gas profile have also been derived in the context of feedback which modifies the distribution away from the NFW profile by altering the entropy distribution of the gas. Mathews & Prochaska (2017) introduced such a model to investigate the observed profile of N OVI absorption in present-day L * galaxies. We generalize their modified NFW (mNFW) model as,…”

Section: Halo Modelsmentioning

confidence: 99%

“…High column density measurements of O +5 have revealed a more highly-ionized plasma, interpreted by many as a tracer of the predicted T 10 6 K virialized halo gas (e.g. Oppenheimer et al 2016;Faerman et al 2017;Mathews & Prochaska 2017). Estimating the mass of this putative, hot-phase is even more challenging because it is difficult to assess the degree of H i absorption associated with it and one rarely has access to neighboring ions of the same element to constrain the ionization state of the gas.…”

Section: Introductionmentioning

confidence: 99%

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Probing Galactic Halos with Fast Radio Bursts

Prochaska

Zheng

2019

Monthly Notices of the Royal Astronomical Society

212

247

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The precise localization (< 1 ) of multiple fast radio bursts (FRBs) to z > 0.1 galaxies has confirmed that the dispersion measures (DMs) of these enigmatic sources afford a new opportunity to probe the diffuse ionized gas around and in between galaxies. In this manuscript, we examine the signatures of gas in dark matter halos (aka halo gas) on DM observations in current and forthcoming FRB surveys. Combining constraints from observations of the high velocity clouds, O vii absorption, and the DM to the Large Magellanic Cloud with hydrostatic models of halo gas, we estimate that our Galactic halo will contribute DM MW,halo ≈ 50 − 80pc cm −3 from the Sun to 200 kpc independent of any contribution from the Galactic ISM. Extending analysis to the Local Group, we demonstrate that M31's halo will be easily detected by high-sample FRB surveys (e.g. CHIME) although signatures from a putative Local Group medium may compete. We then review current empirical constraints on halo gas in distant galaxies and discuss the implications for their DM contributions. We further examine the DM probability distribution function of a population of FRBs at z 0 using an updated halo mass function and new models for the halo density profile. Lastly, we illustrate the potential of FRB experiments for resolving the baryonic fraction of halos by analyzing simulated sightlines through the CASBaH survey. All of the code and data products of our analysis are available at https://github.com/FRBs.

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Section: Halo Modelsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Probing Galactic Halos with Fast Radio Bursts

Prochaska

Zheng

2019

Monthly Notices of the Royal Astronomical Society

212

247

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“…29) while f O vi which depends mainly on T is roughly independent of M. Hence, in principle a cooling flow with M ∼ 25 SFR could reproduce the O vi observations, though such a model would have t cool < t ff and hence would be unstable. It has been shown that any model which assumes O vi traces radiatively cooling gas requires M SFR (Mathews & Prochaska 2017;Faerman et al 2017;McQuinn & Werk 2018;Stern et al 2018).…”

Section: Ovi Absorptionmentioning

confidence: 99%

“…Since the hydrostatic equation on its own is insufficient to fully specify the structure of the halo gas, these studies evoked additional assumptions on the density or entropy profile. Specifically, Maller & Bullock (2004) assumed a flat entropy profile out to R cool , Faerman et al (2017) derived the density profile from the average X-ray emission and absorption in the MW and from the O vi absorption around external galaxies, Mathews & Prochaska (2017) assumed a density which follows the dark matter density with a flat entropy core, and Voit (2018) assumed an entropy profile which yields t cool /t ff ≈ 10 at all radii. In the cooling flow solutions for the MW halo gas , the pressure profile is also close to hydrostatic, since the correction to the momentum equation is of order M 2 , while M is small at halo radii (≈ 0.1 at 100 kpc, eqn.…”

Section: Comparison With Hydrostatic Modelsmentioning

confidence: 99%

“…Preferential heating of the OVI-bearing outer halo: To maintain the large cooling rates implied by the O vi observations, previous studies typically assumed that gas at 100 kpc is heated by supernovae or AGN in the central galaxy (Cen 2013;Liang et al 2016;Mathews & Prochaska 2017;Faerman et al 2017;Suresh et al 2017;McQuinn & Werk 2018). If this is the case, a heating mechanism powered by the central galaxy must avoid depositing most of its energy in the inner 10s of kpc to explain the order-ofmagnitude lower cooling rates inferred from the X-ray observations.…”

Section: Reconciling Ovi and X-ray Observationsmentioning

confidence: 99%

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Cooling flow solutions for the circumgalactic medium

Stern

Fielding

Faucher-Giguère

et al. 2019

Monthly Notices of the Royal Astronomical Society

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ABSTRACT In several models of galaxy formation feedback occurs in cycles or mainly at high redshift. At times and in regions where feedback heating is ineffective, hot gas in the galaxy halo is expected to form a cooling flow, where the gas advects inward on a cooling timescale. Cooling flow solutions can thus be used as a benchmark for observations and simulations to constrain the timing and extent of feedback heating. Using analytic calculations and idealized 3D hydrodynamic simulations, we show that for a given halo mass and cooling function, steady-state cooling flows form a single-parameter family of solutions, while initially hydrostatic gaseous haloes converge on one of these solutions within a cooling time. The solution is thus fully determined once either the mass inflow rate ${\dot{M}}$ or the total halo gas mass are known. In the Milky Way halo, a cooling flow with ${\dot{M}}$ equal to the star formation rate predicts a ratio of the cooling time to the free-fall time of ∼10, similar to some feedback-regulated models. This solution also correctly predicts observed $\rm{O\,{\small VII}}$ and $\rm{O\,{\small VIII}}$ absorption columns, and the gas density profile implied by $\rm{O\,{\small VII}}$ and $\rm{O\,{\small VIII}}$ emission. These results suggest ongoing heating by feedback may be negligible in the inner Milky-Way halo. Extending similar solutions out to the cooling radius however underpredicts observed $\rm{O\,{\small VI}}$ columns around the Milky-Way and around other low-redshift star-forming galaxies. This can be reconciled with the successes of the cooling flow model with either a mechanism which preferentially heats the $\rm{O\,{\small VI}}$-bearing outer halo, or alternatively if $\rm{O\,{\small VI}}$ traces cool photoionized gas beyond the accretion shock. We also demonstrate that the entropy profiles of some of the most relaxed clusters are reasonably well described by a cooling flow solution.

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Properties of the circumgalactic medium in simulations compared to observations

Machado

Tissera

Neto

et al. 2018

A&A

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Context. Galaxies are surrounded by extended gaseous halos which store significant fractions of chemical elements. These are syntethized by the stellar populations and later ejected into the circumgalactic medium (CGM) by different mechanism, of which supernova feedback is considered one of the most relevant. Aims. We explore the properties of this metal reservoir surrounding star-forming galaxies in a cosmological context aiming to investigate the chemical loop between galaxies and their CGM, and the ability of the subgrid models to reproduce observational results. Methods. Using cosmological hydrodynamical simulations, we analyse the gas-phase chemical contents of galaxies with stellar masses in the range 10 9 − 10 11 M ⊙ . We estimate the fractions of metals stored in the different CGM phases, and the predicted O vi and Si iii column densities within the virial radius. Results. We find roughly 10 7 M ⊙ of oxygen in the CGM of simulated galaxies having M ⋆ ∼10 10 M ⊙ , in fair agreement with the lower limits imposed by observations. The M oxy is found to correlate with M ⋆ , at odds with current observational trends but in agreement with other numerical results. The estimated profiles of O vi column density reveal a substantial shortage of that ion, whereas Si iii, which probes the cool phase, is overpredicted. Nevertheless, the radial dependences of both ions follow the respective observed profiles. The analysis of the relative contributions of both ions from the hot, warm and cool phases suggests that the warm gas (10 5 K < T < 10 6 K) should be more abundant in order to bridge the mismatch with the observations, or alternatively, that more metals should be stored in this gas-phase. These discrepancies provide important information to improve the subgrid physics models. Our findings show clearly the importance of tracking more than one chemical element and the difficulty of simultaneously satisfying the observables that trace the circumgalactic gas at different physical conditions. Adittionally, we find that the X-ray coronae around the simulated galaxies have luminosities and temperatures in decent agreement with the available observational estimates.

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Circumgalactic Oxygen Absorption and Feedback

Cited by 50 publications

References 30 publications

Probing Galactic Halos with Fast Radio Bursts

Probing Galactic Halos with Fast Radio Bursts

Cooling flow solutions for the circumgalactic medium

Properties of the circumgalactic medium in simulations compared to observations

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