论文标题
MW中的温暖气体：运动学模型
The Warm Gas in the MW: A Kinematical Model
论文作者
论文摘要
我们为银河系含有SI IV的气体开发了运动学模型，以确定其密度分布和运动学。该模型受到从{\ it Hst}/cos档案数据中提取的列密度线形状样品的约束，该数据包含186个AGN视线。 We find that the Si IV ion density distribution is dominated by an extended disk along the $z$-direction (above or below the midplane), i.e., $n(z)=n_0\exp(-(z/z_0)^{0.82})$, where $z_0$ is the scale height of $6.3_{-1.5}^{+1.6}$ kpc (northern半球）和$ 3.6 _ { - 0.9}^{+1.0} $ kpc（南半球）。磁盘在径向方向上的密度分布在$ 15-20 $ kpc上显示出$ n（r _ {\ rm xy}）给出的$ 15-20 $ kpc，= n_0 \ exp（ - （ - （r _ {\ rm xy}/r_0）^{3.36}）^{3.36}） $ r _ {\ rm xy} $和$ z $方向的密度分布的差异表明，\ ion {si} {4}追踪的温暖气体主要与磁盘过程（例如反馈或循环气体）而不是积聚相关。我们估计温暖气体（50 kpc之内）的质量为$ \ log（m（50 {\ rm kpc}）/m_ \ odot）\大约8.1 $（假设$ z \ z \ of0.5z_ \ odot $）和$3σ$上限（$3σ$ $ \ log（m） （不包括麦哲伦系统）。从运动上讲，温暖的气盘几乎与恒星磁盘在$ v _ {\ rm rot} = 215 \ pm3 \ rm〜km〜km〜s^{ - 1} $中，落在平面旋转约8 \ rm〜km〜km〜km〜s^{ - 1}^kpc^kp^km〜km〜km〜s^s^kp^kp^kp^kp^km〜km〜km〜s^{ - 1} $ {-1}同时，我们注意到北半球的温暖气体具有$ v _ {\ rm acc} $ $ 69 \ pm 7 \ rm〜km〜s^s^{ - 1} $的$ v _ {\ rm acc} $ 10 kpc的$ v _ {\ rm acc} $（积聚速度的增值率） $ -0.60 _ { - 0.13}^{+0.11} 〜m_ \ odot \ rm〜 yr^{ - 1} $），而在南半球，没有可测量的增生，上限为$ 0.4〜m_ \ odot \ odot \ odot \ odot \ odot \ rm〜 yr yr^yr^yr^{ - 1} $。
We develop a kinematical model for the Milky Way Si IV-bearing gas to determine its density distribution and kinematics. This model is constrained by a column density line shape sample extracted from the {\it HST}/COS archival data, which contains 186 AGN sight lines. We find that the Si IV ion density distribution is dominated by an extended disk along the $z$-direction (above or below the midplane), i.e., $n(z)=n_0\exp(-(z/z_0)^{0.82})$, where $z_0$ is the scale height of $6.3_{-1.5}^{+1.6}$ kpc (northern hemisphere) and $3.6_{-0.9}^{+1.0}$ kpc (southern hemisphere). The density distribution of the disk in the radial direction shows a sharp edge at $15-20$ kpc given by, $n(r_{\rm XY})=n_0\exp(-(r_{\rm XY}/r_0)^{3.36})$, where $r_0 \approx 12.5\pm0.6$ kpc. The difference of density distributions over $r_{\rm XY}$ and $z$ directions indicates that the warm gas traced by \ion{Si}{4} is mainly associated with disk processes (e.g., feedback or cycling gas) rather than accretion. We estimate the mass of the warm gas (within 50 kpc) is $\log (M(50 {\rm kpc})/M_\odot)\approx8.1$ (assuming $Z\approx0.5Z_\odot$), and a $3σ$ upper limit of $\log (M(250 {\rm kpc})/M_\odot)\approx9.1$ (excluding the Magellanic system). Kinematically, the warm gas disk is nearly co-rotating with the stellar disk at $v_{\rm rot}=215\pm3\rm~km~s^{-1}$, which lags the midplane rotation by about $8\rm~km~s^{-1}~kpc^{-1}$ (within 5 kpc). Meanwhile, we note that the warm gas in the northern hemisphere has significant accretion with $v_{\rm acc}$ of $69\pm 7\rm ~km~s^{-1}$ at 10 kpc (an accretion rate of $-0.60_{-0.13}^{+0.11}~M_\odot\rm~yr^{-1}$), while in the southern hemisphere, there is no measurable accretion, with an upper limit of $0.4~M_\odot\rm~yr^{-1}$.
