论文标题
宇宙中午的CGM与KCWI：Z = 2.071的星形星系流出
The CGM at Cosmic Noon with KCWI: Outflows from a Star-forming Galaxy at z=2.071
论文作者
论文摘要
我们通过KCWI计划从COSMIC中午的CGM提出了第一个结果，该计划在$ z = 2-3 $的情况下研究圆环培养基（CGM）中的气流。将高分辨率VLT/uves Quasar Spectrum，HST/ACS图像和整体场谱与Keck/KCWI结合使用，我们从$ 1.7L _ {\ ast} $ galaaxy at $ z _ {\ rm gal} = 2.0711 $相关的LYA发射从$ 1.7L _ {\ ast} $ galaaxy发射（$ w_r（2796）= 0.24 $ ang）quasar field J143040 $+$+$ 014939。银河系是星形的（$ {\ rm sfr} _ {\ rm fuv} = 37.8 $ m $ _ {\ odot} $ yr $^{ - 1} $）和块状：要么边缘磁盘（$ i = 85^{\ circ} $）或更可能背景类星体沿投影的星系次要轴（$φ= 89^{\ circ} $）以$ d = 66 $ kpc的影响参数探测星系。从吸收系统的光电离建模中，我们推断出$ {\ rm [si/h]} = - 1.5^{+0.4} _ { - 0.3} $ $ {\ rm [si/h]} = -1.5^{+1.5^{ - 0.3} $的总of of $ {\ rm [si/h]} $。吸收系统大约在运动学上对称$ z {\ rm gal} $，完整的MGII速度差异为$ \ sim210 $ km s $ s $^{ - 1} $。鉴于银河系的方向，CGM金属性和气体运动学，我们将这种气体解释为可能已扫除其他材料的流出。通过将吸收作为极性流出锥进行建模，我们发现气体正在减速，平均径向速度$ v _ {\ rm out} = 109-588 $ km s $ s $ s $ s $^{ - 1} $，用于$θ_0= 14^{\ circ} -75^{\ 75^{\ circ} $的一半开头。假设有一个常数$ v _ {\ rm out} $，则平均需要$ t _ {\ rm out} \ sim111-597 $ myr，以达到66 kpc。流出充满活力，质量流率为$ \ dot {m} _ {\ rm out} <52 {\ pm37} $ m $ _ {\ odot} $ yr $^{ - 1} $和$η<1.4 <1.4 {\ pm1.0} $的质量负载因子和质量负载因子。我们的目标是建立一个$ \ sim50 $ mGII吸收器的样本 - 在这个时期，galaxy对，以便在最积极地构建星系时更好地了解气流。
We present the first results from our CGM at Cosmic Noon with KCWI program to study gas flows in the circumgalactic medium (CGM) at $z=2-3$. Combining the power of a high-resolution VLT/UVES quasar spectrum, an HST/ACS image, and integral field spectroscopy with Keck/KCWI, we detected Lya emission from a $1.7L_{\ast}$ galaxy at $z_{\rm gal}=2.0711$ associated with a Lyman limit system with weak MgII ($W_r(2796)=0.24$ Ang) in quasar field J143040$+$014939. The galaxy is star-forming (${\rm SFR}_{\rm FUV}=37.8$ M$_{\odot}$ yr$^{-1}$) and clumpy: either an edge-on disk ($i=85^{\circ}$) or, less likely, a major merger. The background quasar probes the galaxy at an impact parameter of $D=66$ kpc along the projected galaxy minor axis ($Φ=89^{\circ}$). From photoionization modeling of the absorption system, we infer a total line-of-sight CGM metallicity of ${\rm [Si/H]}=-1.5^{+0.4}_{-0.3}$. The absorption system is roughly kinematically symmetric about $z_{\rm gal}$, with a full MgII velocity spread of $\sim210$ km s$^{-1}$. Given the galaxy-quasar orientation, CGM metallicity, and gas kinematics, we interpret this gas as an outflow that has likely swept-up additional material. By modeling the absorption as a polar outflow cone, we find the gas is decelerating with average radial velocity $V_{\rm out}=109-588$ km s$^{-1}$ for half opening angles of $θ_0=14^{\circ}-75^{\circ}$. Assuming a constant $V_{\rm out}$, it would take on average $t_{\rm out}\sim111-597$ Myr for the gas to reach 66 kpc. The outflow is energetic, with a mass outflow rate of $\dot{M}_{\rm out}<52{\pm37}$ M$_{\odot}$ yr$^{-1}$ and mass loading factor of $η<1.4{\pm1.0}$. We aim to build a sample of $\sim50$ MgII absorber--galaxy pairs at this epoch to better understand gas flows when they are most actively building galaxies.
