%0 Journal Article %1 kelly2020origin %A Kelly, Ashley J %A Jenkins, Adrian %A Frenk, Carlos S %D 2020 %K X-ray heating starburst %T The origin of X-ray coronae around simulated disc galaxies %U http://arxiv.org/abs/2005.12926 %X The existence of hot, accreted gaseous coronae around massive galaxies is a long-standing central prediction of galaxy formation models in the $Łambda$CDM 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, $(10^11-10^14) M_ødot$, in the cosmological hydrodynamical EAGLE simulations. We find that the central X-ray emission, $0.10 R_vir$, of halos of mass $10^13 M_ødot$ originates from gas heated by supernovae (SNe). However, beyond this region, a quasi-hydrostatic, accreted atmosphere dominates the X-ray emission in halos of mass $10^12 M_ødot$. We predict that a dependence on halo mass of the hot gas to dark matter mass fraction can significantly change the slope of the $L_X-M_vir$ 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 halos increases with halo mass, we find a steeper slope for the $L_X-M_vir$ in lower mass halos, $10^14 M_ødot$. This varying gas fraction is driven by active galactic nuclei (AGN) 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.

@article{kelly2020origin, abstract = {The existence of hot, accreted gaseous coronae around massive galaxies is a long-standing central prediction of galaxy formation models in the $\Lambda$CDM 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, $\leq 0.10 R_{\mathrm{vir}}$, of halos of mass $\leq 10^{13} \mathrm{M}_\odot$ originates from gas heated by supernovae (SNe). However, beyond this region, a quasi-hydrostatic, accreted atmosphere dominates the X-ray emission in halos of mass $\geq 10^{12} \mathrm{M}_\odot$. We predict that a dependence on halo mass of the hot gas to dark matter mass fraction can significantly change the slope of the $L_{\mathrm{X}}-M_{\mathrm{vir}}$ 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 halos increases with halo mass, we find a steeper slope for the $L_{\mathrm{X}}-M_{\mathrm{vir}}$ in lower mass halos, $\leq 10^{14} \mathrm{M}_\odot$. This varying gas fraction is driven by active galactic nuclei (AGN) 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.}, added-at = {2020-05-28T11:25:54.000+0200}, author = {Kelly, Ashley J and Jenkins, Adrian and Frenk, Carlos S}, biburl = {https://www.bibsonomy.org/bibtex/2b2880bccd534875c2cfeb4487e1ff7fc/kiwasawa}, description = {The origin of X-ray coronae around simulated disc galaxies}, interhash = {545464c24829d130733a01a5fbae2299}, intrahash = {b2880bccd534875c2cfeb4487e1ff7fc}, keywords = {X-ray heating starburst}, note = {cite arxiv:2005.12926Comment: 18 pages, 11 figures, submitted to MNRAS}, timestamp = {2020-05-28T11:25:54.000+0200}, title = {The origin of X-ray coronae around simulated disc galaxies}, url = {http://arxiv.org/abs/2005.12926}, year = 2020 }