We combine 126 new galaxy-O
We combine data sets from the CGM2and CASBaH surveys to model a transition point,
- Award ID(s):
- 2044303
- NSF-PAR ID:
- 10413673
- Publisher / Repository:
- DOI PREFIX: 10.3847
- Date Published:
- Journal Name:
- The Astrophysical Journal
- Volume:
- 948
- Issue:
- 2
- ISSN:
- 0004-637X
- Format(s):
- Medium: X Size: Article No. 114
- Size(s):
- ["Article No. 114"]
- Sponsoring Org:
- National Science Foundation
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Abstract vi absorber pairs from the CGM2survey with 123 pairs drawn from the literature to examine the simultaneous dependence of the column density of Ovi absorbers (N O VI) on galaxy stellar mass, star-formation rate, and impact parameter. The combined sample consists of 249 galaxy-Ovi absorber pairs coveringz = 0–0.6, with host galaxy stellar massesM *= 107.8–1011.2M ⊙and galaxy-absorber impact parametersR ⊥= 0–400 proper kiloparsecs. In this work, we focus on the variation ofN O VIwith galaxy mass and impact parameter among the star-forming galaxies in the sample. We find that the averageN O VIwithin one virial radius of a star-forming galaxy is greatest for star-forming galaxies withM *= 109.2–1010M ⊙. Star-forming galaxies withM *between 108and 1011.2M ⊙can explain most Ovi systems with column densities greater than 1013.5cm−2. Sixty percent of the Ovi mass associated with a star-forming galaxy is found within one virial radius, and 35% is found between one and two virial radii. In general, we find that some departure from hydrostatic equilibrium in the CGM is necessary to reproduce the observed Ovi amount, galaxy mass dependence, and extent. Our measurements serve as a test set for CGM models over a broad range of host galaxy masses. -
Abstract This study addresses how the incidence rate of strong O
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null (Ed.)ABSTRACT We examine the thermodynamic state and cooling of the low-z circumgalactic medium (CGM) in five FIRE-2 galaxy formation simulations of Milky Way-mass galaxies. We find that the CGM in these simulations is generally multiphase and dynamic, with a wide spectrum of largely non-linear density perturbations sourced by the accretion of gas from the intergalactic medium (IGM) and outflows from both the central and satellite galaxies. We investigate the origin of the multiphase structure of the CGM with a particle-tracking analysis and find that most of the low-entropy gas has cooled from the hot halo as a result of thermal instability triggered by these perturbations. The ratio of cooling to free-fall time-scales tcool/tff in the hot component of the CGM spans a wide range of ∼1−100 at a given radius but exhibits approximately constant median values of ∼5−20 at all radii 0.1Rvir < r < Rvir. These are similar to the ≈10−20 value typically adopted as the thermal instability threshold in ‘precipitation’ models of the ICM. Consequently, a one-dimensional model based on the assumption of a constant tcool/tff and hydrostatic equilibrium approximately reproduces the number density and entropy profiles of each simulation but only if it assumes the metallicity profile and temperature boundary condition taken directly from the simulation. We explicitly show that the tcool/tff value of a gas parcel in the hot component of the CGM does not predict its probability of subsequently accreting on to the central galaxy. This suggests that the value of tcool/tff is a poor predictor of thermal stability in gaseous haloes in which large-amplitude density perturbations are prevalent.more » « less
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