论文标题
在红移z <〜0.5处的圆形MGII的完整人口普查
A Complete Census of Circumgalactic MgII at Redshift z<~ 0.5
论文作者
论文摘要
我们使用156个背景准恒星对象（QSO）作为吸收线探针，对380个随机星系附近的MGII吸收气体进行了调查。该样品包括211个分离的（73个静止和138个星形的星系）和43个非分离星系，对MGII吸收和HA发射具有敏感约束。投影距离的范围从d = 9到497 kpc，星系的红移范围从z = 0.10到0.48，而静止框架绝对B波段的大小从$ m _ {\ rm b} = -16.7 $到$ -22.8 $。 Our analysis shows that the rest-frame equivalent width of MgII, $W_r$(2796), depends on halo radius($R_h$), $B$-band luminosity($L_{\rm B}$) and stellar mass ($M_{\rm star}$) of the host galaxies, and declines steeply with increasing $d$ for isolated, star-forming星系。 $ W_R $（2796）对于孤立的，静止的星系或非分离星系都没有明确的趋势。 The covering fraction of MgII absorbing gas $\langle κ\rangle$ is high with $\langle κ\rangle\gtrsim 60$% at $<40$ kpc for isolated galaxies and declines rapidly to $\langle κ\rangle\approx 0$ at $d\gtrsim100$ kpc.在气态半径内，$ \langleκ\ rangle $敏感地取决于$ m _ {\ rm star} $和从HA推断出的特定星形形成率。与大量的静态光环不同，观察到的MGII气体周围的速度分散恒星形成星系与病毒运动的期望一致，病毒运动的期望将单个团块质量限制为$ m _ {\ rm cl} \ gtrsim 10^5 \，\ rm m_ \ odot $ and $ rm m_ \ odot $ sim $ 0.7-2。 \，m_ \ odot \，\ rm yr^{ - 1} $。我们发现MGII吸收对星形成或静态星系的强烈方位角依赖性。我们的结果表明，需要在狭窄空间中对化学富集的气体建立整体描述的均匀，吸收盲样品。
We present a survey of MgII absorbing gas in the vicinity of 380 random galaxies, using 156 background quasi-stellar objects(QSOs) as absorption-line probes. The sample comprises 211 isolated (73 quiescent and 138 star-forming galaxies) and 43 non-isolated galaxies with sensitive constraints for both MgII absorption and Ha emission. The projected distances span a range from d=9 to 497 kpc, redshifts of the galaxies range from z=0.10 to 0.48, and rest-frame absolute B-band magnitudes range from $M_{\rm B}=-16.7$ to $-22.8$. Our analysis shows that the rest-frame equivalent width of MgII, $W_r$(2796), depends on halo radius($R_h$), $B$-band luminosity($L_{\rm B}$) and stellar mass ($M_{\rm star}$) of the host galaxies, and declines steeply with increasing $d$ for isolated, star-forming galaxies. $W_r$(2796) exhibits no clear trend for either isolated, quiescent galaxies or non-isolated galaxies. The covering fraction of MgII absorbing gas $\langle κ\rangle$ is high with $\langle κ\rangle\gtrsim 60$% at $<40$ kpc for isolated galaxies and declines rapidly to $\langle κ\rangle\approx 0$ at $d\gtrsim100$ kpc. Within the gaseous radius, $\langle κ\rangle$ depends sensitively on both $M_{\rm star}$ and the specific star formation rate inferred from Ha. Different from massive quiescent halos, the observed velocity dispersion of MgII gas around star-forming galaxies is consistent with expectations from virial motion, which constrains individual clump mass to $m_{\rm cl} \gtrsim 10^5 \,\rm M_\odot$ and cool gas accretion rate of $\sim 0.7-2 \,M_\odot\,\rm yr^{-1}$. We find no strong azimuthal dependence of MgII absorption for either star-forming or quiescent galaxies. Our results highlight the need of a homogeneous, absorption-blind sample for establishing a holistic description of chemically-enriched gas in the circumgalactic space.
