Massive Warm/Hot Galaxy Coronae as Probed by Uv/X-Ray Oxygen Absorption and Emission. I. Basic Model

Faerman, Yakov; Sternberg, A.; McKee, Christopher F.

doi:10.3847/1538-4357/835/1/52

Cited by 152 publications

(179 citation statements)

References 122 publications

(172 reference statements)

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“…Both observations and theoretical models imply that the gas density in the CGM falls with radius roughly like r −1 to r −1.5 (Maller & Bullock 2004;Miller & Bregman 2013Werk et al 2014;Voit et al 2017;Faermon et al 2017). When we take an initial radial density profile for the volume-filling phase of n vf ∝1/r, and following the self-similar solutions for energy-driven bubbles in Dyson (1989), the radius of the expanding bubble is given by ), M hot,10 is the total mass of the volume-filling phase out to a radius of 200 kpc in units of 10 10 M e , and t 8 is the time since the starburst began, given in units of 10 8 years.…”

Section: A Two-phase Cgmmentioning

confidence: 97%

COS-burst: Observations of the Impact of Starburst-driven Winds on the Properties of the Circum-galactic Medium

Heckman

Borthakur

Wild

et al. 2017

ApJ

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We report on observations made with the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST) using background quasi-stellar objects to probe the circum-galactic medium (CGM) around 17 low-redshift galaxies that are undergoing or have recently undergone a strong starburst (the COS-Burst program). The sightlines extend out to roughly the virial radius of the galaxy halo. We construct control samples of normal star-forming low-redshift galaxies from the COS/HST archive that match the starbursts in terms of galaxy stellar mass and impact parameter. We find clear evidence that the CGM around the starbursts differs systematically compared to the control galaxies. The Lyα, Si III, C IV, and possibly O VI absorption lines are stronger as a function of impact parameter, and the ratios of the equivalent widths of C IV/Lyα and Si III/Lyα are both higher than in normal starforming galaxies. We also find that the widths and the velocity offsets (relative to v sys ) of the Lyα absorption lines are significantly larger in the CGM of the starbursts, implying velocities of the absorbing material that are roughly twice the halo virial velocity. We show that these properties can be understood as a consequence of the interaction between a starburst-driven wind and the preexisting CGM. These results underscore the importance of winds driven from intensely star-forming galaxies in helping drive the evolution of galaxies and the intergalactic medium. They also offer a new probe of the properties of starburst-driven winds and of the CGM itself.

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Section: A Two-phase Cgmmentioning

confidence: 97%

COS-burst: Observations of the Impact of Starburst-driven Winds on the Properties of the Circum-galactic Medium

Heckman

Borthakur

Wild

et al. 2017

ApJ

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“…Dai et al 2012;Bogdán et al 2013;Anderson, Churazov & Bregman 2016). By combining observations of Ovi absorbers around star-forming galaxies (from the COS-Halos survey, see below) together with the Ovii and Oviii absorption associated with our Galaxy in a single model of corona, Faerman, Sternberg & McKee (2017) found that the typical coronal gas mass of a Milky-Way-like galaxy is ∼ 1.35 × 10 11 M . Regarding the cooler phase of the CGM, Hi observations in the Milky Way revealed a population of HVCs, characterized by velocities inconsistent with the rotation of the Galactic disc (e.g.…”

Section: Introductionmentioning

confidence: 92%

The survival of gas clouds in the circumgalactic medium of Milky Way-like galaxies

Armillotta

Fraternali

Werk

et al. 2017

Monthly Notices of the Royal Astronomical Society

166

137

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Observational evidence shows that low-redshift galaxies are surrounded by extended haloes of multiphase gas, the so-called 'circumgalactic medium' (CGM). To study the survival of relatively cool gas (T < 10 5 K) in the CGM, we performed a set of hydrodynamical simulations of cold (T = 10 4 K) neutral gas clouds travelling through a hot (T = 2 × 10 6 K) and low-density (n = 10 −4 cm −3 ) coronal medium, typical of Milky Way-like galaxies at large galactocentric distances (∼ 50 − 150 kpc). We explored the effects of different initial values of relative velocity and radius of the clouds. Our simulations were performed on a two-dimensional grid with constant mesh size (2 pc) and they include radiative cooling, photoionization heating and thermal conduction. We found that for large clouds (radii larger than 250 pc) the cool gas survives for very long time (larger than 250 Myr): despite that they are partially destroyed and fragmented into smaller cloudlets during their trajectory, the total mass of cool gas decreases at very low rates. We found that thermal conduction plays a significant role: its effect is to hinder formation of hydrodynamical instabilities at the cloud-corona interface, keeping the cloud compact and therefore more difficult to destroy. The distribution of column densities extracted from our simulations are compatible with those observed for low-temperature ions (e.g. Siii and Siiii) and for high-temperature ions (Ovi) once we take into account that Ovi covers much more extended regions than the cool gas and, therefore, it is more likely to be detected along a generic line of sight.

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“…where we used Λ = Λ ⊙ (T, n)Z ′ , ignoring cooling by hydrogen and helium and resulting in a lower limit for the cooling time. Given the shape of the cooling function and the OVI 8 In Faerman et al (2017) we used the isobaric cooling time, longer by a factor of 5/3 and t dyn = r 3 /GM, shorter by √ 2. Thus, the ratio t cool /t dyn from FSM17 should be scaled down by ≈ 2.35 to compare with the values adopted here.…”

Section: Timescalesmentioning

confidence: 99%

Massive Warm/Hot Galaxy Coronae. II. Isentropic Model

Faerman

Sternberg

McKee

2020

ApJ

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We construct a new analytic phenomenological model for the extended circumgalactic material (CGM) of L * galaxies. Our model reproduces the OVII/OVIII absorption observations of the Milky Way (MW) and the OVI measurements reported by the COS-Halos and eCGM surveys. The warm/hot gas is in hydrostatic equilibrium in a MW gravitational potential, and we adopt a barotropic equation of state, resulting in a temperature variation as a function of radius. A pressure component with an adiabatic index of γ = 4/3 is included to approximate the effects of a magnetic field and cosmic rays. We introduce a metallicity gradient motivated by the enrichment of the inner CGM by the Galaxy. We then present our fiducial model for the corona, tuned to reproduce the observed OVI-OVIII column densities, and with a total mass of M CGM ≈ 5.5 × 10 10 M ⊙ inside r CGM ≈ 280 kpc. The gas densities in the CGM are low (n H = 10 −5 − 3 × 10 −4 cm −3 ) and its collisional ionization state is modified by the metagalactic radiation field (MGRF). We show that for OVI-bearing warm/hot gas with typical observed column densities N OVI ∼ 3 × 10 14 cm −2 at large ( 100 kpc) impact parameters from the central galaxies, the ratio of the cooling to dynamical times, t cool /t dyn , has a model-independent upper limit of ∼ 5. In our model, t cool /t dyn at large radii is ∼ 2 − 3. We present predictions for a wide range of future observations of the warm/hot CGM, from UV/X-ray absorption and emission spectroscopy, to dispersion measure (DM) and Sunyaev-Zeldovich CMB measurements.

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Massive Warm/Hot Galaxy Coronae as Probed by Uv/X-Ray Oxygen Absorption and Emission. I. Basic Model

Cited by 152 publications

References 122 publications

COS-burst: Observations of the Impact of Starburst-driven Winds on the Properties of the Circum-galactic Medium

COS-burst: Observations of the Impact of Starburst-driven Winds on the Properties of the Circum-galactic Medium

The survival of gas clouds in the circumgalactic medium of Milky Way-like galaxies

Massive Warm/Hot Galaxy Coronae. II. Isentropic Model

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