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Diffuse coronae in cosmological simulations of milky way-sized galaxies


Sokołowska, A; Mayer, L; Babul, A; Madau, P; Shen, S (2016). Diffuse coronae in cosmological simulations of milky way-sized galaxies. The Astrophysical Journal, 819(1):21.

Abstract

We investigate the properties of halo gas using three cosmological “zoom-in” simulations of realistic Milky Way-galaxy analogs with varying sub-grid physics. In all three cases, the mass of hot (T > 106 K) halo gas is ˜1% of the host's virial mass. The X-ray luminosity of two of the runs is consistent with observations of the Milky Way, while the third simulation is X-ray bright and resembles more closely a very massive, star-forming spiral. Hot halos extend to 140 kpc from the galactic center and are surrounded by a bubble of warm-hot (T={10}5-{10}6 K) gas that extends to the virial radius. Simulated halos agree well outside 20-30 kpc with the β-model of Miller & Bregman based on O vii absorption and O viii emission measurements. Warm-hot and hot gas contribute up to 80% of the total gas reservoir, and contain nearly the same amount of baryons as the stellar component. The mass of warm-hot and hot components falls into the range estimated for {L}* galaxies. With key observational constraints on the density of the Milky Way corona being satisfied, we show that concealing of the ubiquitous warm-hot baryons, along with the ejection of just 20%-30% of the diffuse gas out of the potential wells by supernova-driven outflows, can solve the “missing baryon problem.” The recovered baryon fraction within 3 virial radii is 90% of the universal value. With a characteristic density of ˜10-4 cm-3 at 50-80 kpc, diffuse coronae meet the requirement for fast and complete ram-pressure stripping of the gas reservoirs in dwarf galaxy satellites.

Abstract

We investigate the properties of halo gas using three cosmological “zoom-in” simulations of realistic Milky Way-galaxy analogs with varying sub-grid physics. In all three cases, the mass of hot (T > 106 K) halo gas is ˜1% of the host's virial mass. The X-ray luminosity of two of the runs is consistent with observations of the Milky Way, while the third simulation is X-ray bright and resembles more closely a very massive, star-forming spiral. Hot halos extend to 140 kpc from the galactic center and are surrounded by a bubble of warm-hot (T={10}5-{10}6 K) gas that extends to the virial radius. Simulated halos agree well outside 20-30 kpc with the β-model of Miller & Bregman based on O vii absorption and O viii emission measurements. Warm-hot and hot gas contribute up to 80% of the total gas reservoir, and contain nearly the same amount of baryons as the stellar component. The mass of warm-hot and hot components falls into the range estimated for {L}* galaxies. With key observational constraints on the density of the Milky Way corona being satisfied, we show that concealing of the ubiquitous warm-hot baryons, along with the ejection of just 20%-30% of the diffuse gas out of the potential wells by supernova-driven outflows, can solve the “missing baryon problem.” The recovered baryon fraction within 3 virial radii is 90% of the universal value. With a characteristic density of ˜10-4 cm-3 at 50-80 kpc, diffuse coronae meet the requirement for fast and complete ram-pressure stripping of the gas reservoirs in dwarf galaxy satellites.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Institute for Computational Science
Dewey Decimal Classification:530 Physics
Language:English
Date:2016
Deposited On:04 Jan 2017 08:08
Last Modified:02 Feb 2018 11:13
Publisher:IOP Publishing
ISSN:1538-4357
OA Status:Hybrid
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.3847/0004-637X/819/1/21

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