The Hot Circumgalactic Medium of the Milky Way: Evidence for Supervirial, Virial, and Subvirial Temperatures; Nonsolar Chemical Composition; and Nonthermal Line Broadening

被引:33
作者
Das, Sanskriti [1 ]
Mathur, Smita [1 ,2 ]
Gupta, Anjali [1 ,3 ]
Krongold, Yair [4 ]
机构
[1] Ohio State Univ, Dept Astron, 140 West 18th Ave, Columbus, OH 43210 USA
[2] Ctr Cosmol & Astroparticle Phys, 191 West Woodruff Ave, Columbus, OH 43210 USA
[3] Columbus State Community Coll, 550 East Spring St, Columbus, OH 43210 USA
[4] Univ Nacl Autonoma Mexico, Inst Astron, Mexico City 04510, DF, Mexico
基金
美国国家航空航天局; 芬兰科学院;
关键词
X-RAY-ABSORPTION; LOW-REDSHIFT; O VI; COSMOLOGICAL SIMULATIONS; INTERGALACTIC MEDIUM; GAS; HALO; CHANDRA; FOREST; ORIGIN;
D O I
10.3847/1538-4357/ac0e8e
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
For the first time, we present the simultaneous detection and characterization of three distinct phases at >10(5) K in z = 0 absorption using deep Chandra observations toward Mrk 421. The extraordinarily high signal-to-noise ratio (>= 60) of the spectra has allowed us to detect a hot phase of the Milky Way circumgalactic medium (CGM) at 3.2(-0.5)(+1.5) x 10(7) K coexisting with a warm-hot phase at 1.5 +/- 0.1 x 10(6) K and a warm phase at 3.0 +/- 0.4 x 10(5) K. The warm-hot phase is at the virial temperature of the Galaxy, and the warm phase may have cooled from the warm-hot phase, but the supervirial hot phase remains a mystery. We find that [C/O] in the warm and warm-hot phases, [Mg/O] in the warm-hot phase, and [Ne/O] in the hot phase are supersolar, and the hot and the warm-hot phases are alpha-enhanced. Nonthermal line broadening is evident in the warm-hot and the hot phases, and it dominates the total line broadening. Our results indicate that the >10(5) K CGM is a complex ecosystem. It provides insights on the thermal and chemical history of the Milky Way CGM and theories of galaxy evolution.
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页数:15
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