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arXiv 1405.4307astro-ph.GA
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镓富螺旋群中$10^{5-6}$ K气体的吸收线探测

Absorption-Line Detections of $10^{5-6}$ K Gas in Spiral-Rich Groups of Galaxies

J. T. Stocke, B. A. Keeney, C. W. Danforth, D. Syphers, H. Yamamoto, J. M. Shull, J. C. Green, C. Froning, B. D. Savage, B. Wakker, T. -S. Kim, E. V. Ryan-Weber, G. G. Kacprzak

摘要:

利用哈勃太空望远镜(HST)上的宇宙起源光谱仪(COS),COS科学小组对14个明亮的类星体进行了高信噪比的调查。在之前的一篇论文(Savage等人,2014)中,这些远紫外光谱被用于发现14种“温”($T > 10^5$ K)吸收剂,使用宽Lyα和O VI吸收剂的组合。使用稍微放松的拟合标准对这种新类型的吸收体中的一些进行重新分析,发现在该样品中可能存在多达20个暖吸收体。在这些视线周围进行了一次浅的、宽的光谱星系红移巡天,以研究温暖的吸收体环境,发现这是富含螺旋的星系群或星系团外围,径向速度色散为σ = 250-750 km/s。虽然2σ证据支持这一假设,即这些星系团与星系群有关,而不是与个别最近的星系有关,但这一证据具有相当大的系统不确定性,并且基于小样本量,因此并不完全是结论性的。如果这些星协是与星系群有关,那么观测到的暖吸收体的频率(dN/dz = 3.5-5每单位红移)要求它们非常大(在高覆盖因子下,半径约为1 Mpc)。这些温暖的吸收体很可能是界面气体云,其存在意味着存在一种更热的($T \sim 10^{6.5}$ K)、扩散的和可能非常大的($>10^{11}~M_{\odot}$)组内介质,这种介质尚未被直接探测到。

英文摘要:

Using the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST) the COS Science Team has conducted a high signal-to-noise survey of 14 bright QSOs. In a previous paper (Savage et al. 2014) these far-UV spectra were used to discover 14 "warm" ($T > 10^5$ K) absorbers using a combination of broad Lyα and O VI absorptions. A reanalysis of a few of this new class of absorbers using slightly relaxed fitting criteria finds as many as 20 warm absorbers could be present in this sample. A shallow, wide spectroscopic galaxy redshift survey has been conducted around these sight lines to investigate the warm absorber environment, which is found to be spiral-rich galaxy groups or cluster outskirts with radial velocity dispersions of σ = 250-750 km/s. While 2σ evidence is presented favoring the hypothesis that these absorptions are associated with the galaxy groups and not with the individual, nearest galaxies, this evidence has considerable systematic uncertainties and is based on a small sample size so it is not entirely conclusive. If the associations are with galaxy groups, the observed frequency of warm absorbers (dN/dz = 3.5-5 per unit redshift) requires them to be very large (~1 Mpc in radius at high covering factor). Most likely these warm absorbers are interface gas clouds whose presence implies the existence of a hotter ($T \sim 10^{6.5}$ K), diffuse and probably very massive ($>10^{11}~M_{\odot}$) intra-group medium which has yet to be detected directly.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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