A Universal Entropy Profile for the Hot Atmospheres of Galaxies and Clusters within R<sub>2500</sub>

Babyk, Iu.; McNamara, B. R.; Nulsen, P. E. J.; Russell, H. R.; Vantyghem, A. N.; Hogan, M. T.; Pulido, F.A.

doi:10.3847/1538-4357/aacce5

Cited by 79 publications

(79 citation statements)

References 63 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The index of this power law was first predicted by Kaiser (1991), with an index of α ∼ 1.1. Observations have confirmed the rough picture of a power law K ∝ r α with a α ∼ 0.9 − 1.5 slope (Werner et al 2012;Babyk et al 2018). Meanwhile, the density of the volume-filling phase has been mostly found to follow a power law ρ ∝ −β with slope β ∼ 1 − 2 (Werk et al 2016;Bregman et al 2018), which, as we show in section 2.4 of this paper, is consistent with a hot halo with entropy slope of α ∼ 1.1 in hydrostatic equilibrium.…”

Section: Structure and Kinematics Of The Cgmmentioning

confidence: 58%

Entropy-driven winds: Outflows and fountains lifted gently by buoyancy

Keller

Kruijssen

Wadsley

2020

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We present a new theoretical framework for using entropy to understand how outflows driven by supernovae are launched from disc galaxies: via continuous, buoyant acceleration through the circumgalactic medium (CGM). When young star clusters detonate supernovae in the interstellar medium (ISM) of a galaxy, they generate hot, diffuse bubbles that push on the surrounding ISM and evaporate that ISM into their interiors. As these bubbles reach the scale height of the ISM, they break out of the disc, rising into the CGM. Once these bubbles break out, if they have sufficiently high entropy, they will feel an upward acceleration, owing to a local buoyant force. This upward force will accelerate these bubbles, driving them to high galactocentric radii, keeping them in the CGM for > Gyr, even if their initial velocity is much lower than the local escape velocity. We derive an equation of motion for these entropy-driven winds that connects the ISM properties, halo mass, and CGM profile of galaxies to the ultimate evolution of feedback-driven winds. We explore the parameter space of these equations, and show how this novel mechanism can explain both self-consistent simulations of star formation and galactic outflows as well as the new wealth of observations of CGM kinematics. We show that these entropy-driven winds can produce long wind recycling times, while still carrying a significant amount of mass. Comparisons to simulations and observations show entropy-driven winds convincingly explain the kinematics of galactic outflows.

show abstract

Section: Structure and Kinematics Of The Cgmmentioning

confidence: 58%

Entropy-driven winds: Outflows and fountains lifted gently by buoyancy

Keller

Kruijssen

Wadsley

2020

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

show abstract

“…In contrast, the observed entropy profile appears to flatten, reaching K ∝ r 0.7 at small scales (Panagoulia et al 2014;Babyk et al 2018). The flattening of the profile appears to occur near R cool , suggesting that feedback affects the intracluster medium out to the maximum radius where it is actively cooling.…”

Section: Clustersmentioning

confidence: 94%

Cooling flow solutions for the circumgalactic medium

Stern

Fielding

Faucher-Giguère

et al. 2019

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

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.

show abstract

“…Data reduction was done using CIAO version 4.8 and CALDB version 4.7.1 (see Babyk et al 2018a;Hogan et al 2017a for more details). Chandra observations were downloaded from HEASARC 5 archive.…”

Section: Data Processingmentioning

confidence: 99%

“…Here we present profiles of temperature, density, cooling, mass and free-fall time for the range of radii ∼ 0.1-50.0 kpc. Analysis of entropy profiles is presented in Babyk et al (2018b). The multi-component spectral model described above was applied, and the output temperature and normalization parameter of APEC model were extracted.…”

Section: Galaxy Propertiesmentioning

confidence: 99%

See 1 more Smart Citation

Origins of Molecular Clouds in Early-type Galaxies

Babyk

McNamara

Tamhane

et al. 2019

ApJ

Self Cite

View full text Add to dashboard Cite

We analyze Chandra observations of the hot atmospheres of 40 early spiral and elliptical galaxies. Using new temperature, density, cooling time, and mass profiles, we explore relationships between their hot atmospheres and cold molecular gas. Molecular gas mass correlates with atmospheric gas mass and density over four decades from central galaxies in clusters to normal giant ellipticals and early spirals. The mass and density relations follow power laws: M mol ∝ M 1.4±0.1 X and M mol ∝ n 1.8±0.3 e , respectively, at 10 kpc. The ratio of molecular gas to atmospheric gas within a 10 kpc radius lies between 3% and 10% for early-type galaxies and between 3% and 50% for central galaxies in clusters. Molecular gas mass is correlated with AGN radio mechanical power, with the scaling M mol ∝ P 0.8±0.1 jet . Early-type galaxies have detectable levels of molecular gas when their atmospheric cooling times falls below ∼ Gyr at a radius of 10 kpc. A similar trend is found in central cluster galaxies. We find no relationship between the ratio of the cooling time to free fall time, t c /t ff , and the presence or absence of molecular clouds in early-type galaxies. Molecular gas related to the hot atmosphere is thus formed internally, from stellar mass loss or cooling from the atmosphere. The correlation between AGN jet power and molecular gas mass is consistent with AGN having been fueled by accretion of molecular gas.

show abstract

A Universal Entropy Profile for the Hot Atmospheres of Galaxies and Clusters within R₂₅₀₀

Cited by 79 publications

References 63 publications

Entropy-driven winds: Outflows and fountains lifted gently by buoyancy

Entropy-driven winds: Outflows and fountains lifted gently by buoyancy

Cooling flow solutions for the circumgalactic medium

Origins of Molecular Clouds in Early-type Galaxies

Contact Info

Product

Resources

About

A Universal Entropy Profile for the Hot Atmospheres of Galaxies and Clusters within R2500

Cited by 79 publications

References 63 publications

Entropy-driven winds: Outflows and fountains lifted gently by buoyancy

Entropy-driven winds: Outflows and fountains lifted gently by buoyancy

Cooling flow solutions for the circumgalactic medium

Origins of Molecular Clouds in Early-type Galaxies

Contact Info

Product

Resources

About

A Universal Entropy Profile for the Hot Atmospheres of Galaxies and Clusters within R₂₅₀₀