Affiliation:
1. Institute for Computational Cosmology, Department of Physics, Durham University, Durham DH1 3LE, UK
Abstract
ABSTRACT
The existence of hot, accreted gaseous coronae around massive galaxies is a long-standing central prediction of galaxy formation models in the ΛCDM cosmology. While observations now confirm that extraplanar hot gas is present around late-type galaxies, the origin of the gas is uncertain with suggestions that galactic feedback could be the dominant source of energy powering the emission. We investigate the origin and X-ray properties of the hot gas that surrounds galaxies of halo mass, $(10^{11}\!-\!10^{14}) \, \mathrm{M}_\odot$, in the cosmological hydrodynamical eagle simulations. We find that the central X-ray emission, ≤0.10Rvir, of haloes of mass $\le 10^{13} \, \mathrm{M}_\odot$ originates from gas heated by supernovae (SNe). However, beyond this region, a quasi-hydrostatic, accreted atmosphere dominates the X-ray emission in haloes of mass $\ge 10^{12} \, \mathrm{M}_\odot$. We predict that a dependence on halo mass of the hot gas to dark matter mass fraction can significantly change the slope of the LX–Mvir relation (which is typically assumed to be 4/3 for clusters) and we derive the scaling law appropriate to this case. As the gas fraction in haloes increases with halo mass, we find a steeper slope for the LX–Mvir in lower mass haloes, $\le 10^{14} \, \mathrm{M}_\odot$. This varying gas fraction is driven by active galactic nuclei feedback. We also identify the physical origin of the so-called ‘missing feedback’ problem, the apparently low X-ray luminosities observed from high star-forming, low-mass galaxies. This is explained by the ejection of SNe-heated gas from the central regions of the halo.
Funder
Science and Technology Facilities Council
European Research Council
Publisher
Oxford University Press (OUP)
Subject
Space and Planetary Science,Astronomy and Astrophysics
Cited by
12 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献