THE HIGHLY IONIZED CIRCUMGALACTIC MEDIUM IS KINEMATICALLY UNIFORM AROUND GALAXIES
THE HIGHLY IONIZED CIRCUMGALACTIC MEDIUM IS KINEMATICALLY UNIFORM AROUND GALAXIES
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高度电离的环星系介质在星系周围的运动学上是均匀的
DOI：
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
J. Charlton
中科院分区：
文献类型：
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作者：
N. Nielsen;G. Kacprzak;S. Muzahid;C. Churchill;M. Murphy;J. Charlton
环星系介质（CGM）被发现集中在沿着主星系的投影长轴和短轴。这表明O vi分别追踪吸积和流出的气体，它们是星系重子循环的关键组成部分。我们进一步研究这一点，通过检查29 O VI吸收与星系的运动学作为星系的颜色，倾角和方位角的函数。每个星系都用哈勃太空望远镜（HST）成像，并在附近（kpc）背景类星体的COS/HST光谱中检测到吸收。我们使用像素速度两点相关函数来表征吸收体的速度扩散，这是以前使用的Mg II星系对样本的方法。O VI的吸收速度扩展比Mg II，这表明这两种离子跟踪CGM的不同成分。再次，在对比Mg二，O六吸收速度蔓延是相似的，无论星系的颜色，倾角和方位角。这表明高电离气体的运动学并不受星系中当前星星形成活动的强烈影响。O VI吸收的运动学均匀性及其主要沿沿着投影星系长轴和短轴观察的趋势可能是由于星系周围电离条件和气体密度的变化。处于中间方位角的气体可以被电离出Ovi相，可能导致处于较高电离状态的气体的分布的方位角依赖性。
The circumgalactic medium (CGM) traced by O vi doublet absorption has been found to concentrate along the projected major and minor axes of the host galaxies. This suggests that O vi traces accreting and outflowing gas, respectively, which are key components of the baryon cycle of galaxies. We investigate this further by examining the kinematics of 29 O vi absorbers associated with galaxies at as a function of galaxy color, inclination, and azimuthal angle. Each galaxy was imaged with the Hubble Space Telescope (HST), and the absorption was detected in COS/HST spectra of nearby ( kpc) background quasars. We use the pixel-velocity two-point correlation function to characterize the velocity spread of the absorbers, which is a method used previously for a sample of Mg ii absorber–galaxy pairs. The absorption velocity spread for O vi is more extended than Mg ii, which suggests that the two ions trace differing components of the CGM. Again, in contrast to Mg ii, the O vi absorption velocity spreads are similar regardless of galaxy color, inclination, and azimuthal angle. This indicates that the kinematics of the high-ionization gas is not strongly influenced by the current star formation activity in the galaxy. The kinematic homogeneity of O vi absorption and its tendency to be observed mainly along the projected galaxy major and minor axes is likely due to varying ionization conditions and gas densities about the galaxy. Gas in intermediate azimuthal angles may be ionized out of the O vi phase, possibly resulting in an azimuthal angle dependence of the distribution of gas in higher ionization states.