The Warm Gaseous Disk and the Anisotropic Circumgalactic Medium of the Milky Way

Qu, Zhijie; Bregman, Joel N.

doi:10.3847/1538-4357/ab2a0b

Cited by 23 publications

(18 citation statements)

References 84 publications

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“…In contrast, shocks are prevalent in non-CR haloes around and within the virial radius which heats up the halo gas to the virial temperature; the halo is inflow-dominated, and outflows are sparse and trapped inside the virial radius (the latter point is discussed in details in Hopkins et al 2020a). Compared to the MHD+ case, the CR+ run shows highly anisotropic spatial structures (Qu & Bregman 2019).…”

Section: Figurementioning

confidence: 94%

Virial shocks are suppressed in cosmic ray-dominated galaxy haloes

Kereš

Chan

et al. 2021

Monthly Notices of the Royal Astronomical Society

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We study the impact of cosmic rays (CRs) on the structure of virial shocks, using a large suite of high-resolution cosmological FIRE-2 simulations accounting for CR injection by supernovae. In Milky Way-mass, low-redshift (z ≲ 1−2) haloes, which are expected to form ‘hot haloes’ with slowly cooling gas in quasi-hydrostatic equilibrium (with a stable virial shock), our simulations without CRs do exhibit clear virial shocks. The cooler phase condensing out from inflows becomes pressure confined to overdense clumps, embedded in low-density, volume-filling hot gas with volume-weighted cooling time longer than inflow time. The gas thus transitions sharply from cool free-falling inflow, to hot and thermal-pressure supported at approximately the virial radius (≈Rvir), and the shock is quasi-spherical. With CRs, we previously argued that haloes in this particular mass and redshift range build up CR-pressure-dominated gaseous haloes. Here, we show that when CR pressure dominates over thermal pressure, there is no significant virial shock. Instead, inflowing gas is gradually decelerated by the CR pressure gradient and the gas is relatively subsonic out to and even beyond Rvir. Rapid cooling also maintains subvirial temperatures in the inflowing gas within ∼Rvir.

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Section: Figurementioning

confidence: 94%

Virial shocks are suppressed in cosmic ray-dominated galaxy haloes

Kereš

Chan

et al. 2021

Monthly Notices of the Royal Astronomical Society

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“…The purple circles are the SZ signal inferred from X-ray observations, mostly of massive spiral galaxies(Li et al 2018), while the black squares are the stacked galaxies from Planck Collaboration et al (2013), mostly massive early type galaxies in the centers of galaxy groups and clusters. The blue line is our scaling relationship for Y for the hot halo gas mass ofQu & Bregman (2018a). This relationship falls below our stacked value by a factor of three, it passes within a factor of two of the massive spirals, and lies an order of magnitude below the stacks from PlanckCollaboration et al (2013).…”

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confidence: 50%

“…The model was developed for comparison with the columns of ionic species, so the cooling function is corrected for photoionization and here we use the results of this TPIE case. At R 200 , the model gas mass is about half of the value for the stack, but the better comparison may be the SZ Y value, which we have calculated here, based on the Qu & Bregman (2018a) work. This work provides M * , M gas and massweighted temperatures as a function of M h , and the results are shown in Figure 11.…”

Section: Comparison To Semi-analytic Modelsmentioning

confidence: 71%

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Hot Extended Galaxy Halos Around Local L* Galaxies From Sunyaev-Zeldovich Measurements

Bregman,

Hodges-Kluck,

et al. 2021

Preprint

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Most of the baryons in L * galaxies are unaccounted for and are predicted to lie in hot gaseous halos (T ∼ 10 6.5 K) that may extend beyond R 200 . A hot gaseous halo will produce a thermal Sunyaev-Zeldovich signal that is proportional to the product of the gas mass and the mass-weighted temperature. To best detect this signal, we used a Needlet Independent Linear Combination all-sky Planck map that we produced from the most recent Planck data release, also incorporating WMAP data. The sample is 12 L* spiral galaxies with distances of 3 − 10 Mpc, which are spatially resolved so that contamination from the optical galaxy can be excluded. One galaxy, NGC 891, has a particularly strong SZ signal, and when excluding it, the stack of 11 galaxies is detected at about 4σ (declining with radius) and is extended to at least 250 kpc (≈ R 200 ) at > 99% confidence. The gas mass within a spherical volume to a radius of 250 kpc is 9.8 ± 2.8 × 10 10 M , for T avg = 3 × 10 6 K. This is about 30% of the predicted baryon content of the average galaxy (3.1×10 11 M ), and about equal to the mass of stars, disk gas, and warm halo gas. The remaining missing baryons (≈ 1.4 × 10 11 M , 40-50% of the total baryon content) are likely to be hot and extend to the 400 − 500 kpc volume, if not beyond. The result is higher than predictions, but within the uncertainties.

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“…The warm-hot gas (log T ≈ 5) in galaxies is a unique tracer for accretion and feedback processes, because it is at the peak of the radiative cooling curve, which leads to short cooling timescale (log τ 10 Myr; e.g., Oppenheimer & Schaye 2013;Gnat 2017). The existence of this gas is unstable, so it needs to be refreshed by accretion (e.g., accretion shocks McQuinn & Werk 2018;Qu & Bregman 2018;Stern et al 2018) and feedback processes (e.g., galactic fountain and galactic wind; Shapiro & Field 1976;Bregman 1980;Thompson et al 2016).…”

Section: Introductionmentioning

confidence: 99%

The Warm Gas in the MW: A Kinematical Model

Qu,

Bregman,

Hodges-Kluck

et al. 2020

Preprint

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We develop a kinematical model for the Milky Way Si IV-bearing gas to determine its density distribution and kinematics. This model is constrained by a column density line shape sample extracted from the HST/COS archival data, which contains 186 AGN sight lines. We find that the Si IV ion density distribution is dominated by an extended disk along the z-direction (above or below the midplane), i.e., n(z) = n 0 exp(−(z/z 0 ) 0.82 ), where z 0 is the scale height of 6.3 +1.6 −1.5 kpc (northern hemisphere) and 3.6 +1.0 −0.9 kpc (southern hemisphere). The density distribution of the disk in the radial direction shows a sharp edge at 15 − 20 kpc given by, n(r XY ) = n 0 exp(−(r XY /r 0 ) 3.36 ), where r 0 ≈ 12.5 ± 0.6 kpc. The difference of density distributions over r XY and z directions indicates that the warm gas traced by Si IV is mainly associated with disk processes (e.g., feedback or cycling gas) rather than accretion. We estimate the mass of the warm gas (within 50 kpc) is log(M (50kpc)/M ⊙ ) ≈ 8.1 (assuming Z ≈ 0.5Z ⊙ ), and a 3σ upper limit of log(M (250kpc)/M ⊙ ) ≈ 9.1 (excluding the Magellanic system). Kinematically, the warm gas disk is nearly co-rotating with the stellar disk at v rot = 215 ± 3 km s −1 , which lags the midplane rotation by about 8 km s −1 kpc −1 (within 5 kpc). Meanwhile, we note that the warm gas in the northern hemisphere has significant accretion with v acc of 69 ± 7 km s −1 at 10 kpc (an accretion rate of −0.60 +0.11 −0.13 M ⊙ yr −1 ), while in the southern hemisphere, there is no measurable accretion, with an upper limit of 0.4 M ⊙ yr −1 .

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The Warm Gaseous Disk and the Anisotropic Circumgalactic Medium of the Milky Way

Cited by 23 publications

References 84 publications

Virial shocks are suppressed in cosmic ray-dominated galaxy haloes

Virial shocks are suppressed in cosmic ray-dominated galaxy haloes

Hot Extended Galaxy Halos Around Local L* Galaxies From Sunyaev-Zeldovich Measurements

The Warm Gas in the MW: A Kinematical Model

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