Recently, the temperature T and luminosity L_X of the hot gas halos of early type galaxies have been derived with unprecedented accuracy from Chandra data, for 30 galaxies covering a wider range of galactic luminosity (and central velocity dispersion sigma_c) than before. This work investigates the origin of the observed temperatures, by examining the relationship between them and the galaxy structure, the gas heating due to Type Ia supernovae (SNIa's) and the gravitational potential, and the dynamical status of the gas flow. In galaxies with sigma_c<200 km/s, the T's are close to a fiducial average temperature for the gas when in outflow; at 200<sigma_c (km/s)<250, the T's are generally lower than this, and unrelated with sigma_c, which requires a more complex gas flow status; at larger sigma_c, the T's may increase as sigma_c^2, as expected for infall heating, though heating from SNIa's, independent of sigma_c, should be dominant. All observed T's are larger than the virial temperature, by up to ~0.5 keV. This additional heating can be provided in the X-ray brightest galaxies by SNIa's and infall heating, with a SNIa's energy input even lower than in standard assumptions; in the X-ray fainter ones it can be provided by SNIa's, whose energy input would be required close to the full standard value at the largest sigma_c. This same energy input, though, would produce temperatures larger than observed at low sigma_c, if entirely thermalized. The values of the observed T's increase from outflows to inflows; the gas is relatively hotter in outflows, though, if the T's are rescaled by the virial temperature. For 200<sigma_c(km/s)<250, lower L_X values tend to correspond to lower T's, which deserves further investigation.
Retrieving the hot circumgalactic medium physics from the X-ray radial profile from eROSITA with an IlustrisTNG-based forward model
Max Planck Institute for Extraterrestrial Physics（马克斯·普朗克地外物理研究所）；INAF-Osservatorio Astronomico di Brera（意大利国家天体物理研究所布雷拉天文台）；Como Lake Center for Astrophysics (CLAP)（科莫湖天体物理中心）；Università degli Studi dell’Insubria（因苏布里亚大学）；European Southern Observatory（欧洲南方天文台）
Probing the Hot Gaseous Halos of Milky Way-like Galaxies in the TNG50 simulation
Xiamen University（厦门大学）；Shanghai Jiao Tong University（上海交通大学）；Tsinghua University（清华大学）；Columbia University（哥伦比亚大学）；University of Bologna（博洛尼亚大学）；INAF, Astrophysics and Space Science Observatory Bologna（意大利国家天体物理研究所博洛尼亚天文台与空间科学观测站）；University of Virginia（弗吉尼亚大学）；Massachusetts Institute of Technology（麻省理工学院）
The hot gas mass fraction in halos. From Milky Way-like groups to massive clusters
European Southern Observatory（欧洲南方天文台）；Excellence Cluster ORIGINS（ORIGINS卓越集群）；INAF – Osservatorio Astronomico di Trieste（意大利国家天体物理研究所的里雅斯特天文台）；IFPU – Institute for Fundamental Physics of the Universe（宇宙基础物理研究所）；Universitäts-Sternwarte, Fakultät für Physik, Ludwig-Maximilians-Universität München（慕尼黑大学物理学院大学天文台）；Max-Planck-Institut für Astrophysik（马克斯·普朗克天体物理学研究所）；Universität Innsbruck（因斯布鲁克大学）；Leibniz-Institut für Astrophysik Potsdam (AIP)（波茨坦莱布尼茨天体物理研究所）；International Centre for Radio Astronomy Research（国际射电天文研究中心）
Determining The Galactic Halo's Emission Measure from UV and X-ray Observations
We analyze a pair of Suzaku shadowing observations in order to determine the X-ray spectrum of the Galaxy's gaseous halo. We simultaneously fit the spectra with models having halo, local, and extragalactic components. The intrinsic intensities of the halo OVII triplet and OVIII Lyman alpha emission lines are 9.98^{+1.10}_{-1.99} LU (line unit; photons cm^-2 s^-1 Sr^-1) and 2.66^{+0.37}_{-0.30} LU, respectively. Meanwhile, FUSE OVI observations for the same directions and SPEAR CIV observations for a nearby direction indicate the existence of hot halo gas at temperatures of ~10^{5.0} K to ~10^{…
A Possible Hidden Hot Halo Component Revealed by Joint X-ray and Sunyaev--Zel'dovich Observations
Purple Mountain Observatory, Chinese Academy of Sciences（中国科学院紫金山天文台）；University of Michigan（密歇根大学）；Tsinghua University（清华大学）；University of Massachusetts, Amherst（马萨诸塞大学阿默斯特分校）
The Milky Way's million degree gaseous halo contains a considerable amount of mass that, depending on its structural properties, can be a significant mass component. In order to analyze the structure of the Galactic halo , we use XMM-Newton Reflection Grating Spectrometer archival data and measure OVII K alpha absorption-line strengths toward 26 active galactic nuclei, LMC X-3, and two Galactic sources (4U 1820-30 and X1735-444). We assume a beta-model as the underlying gas density profile and find best-fit parameters of n_o = 0.46^{+0.74}_{-0.35} cm^-3, r_c = 0.35^{+0.29}_{-0.27} kpc, and bet…
