论文标题
气体选择星系中的CO激发和线路能量分布
CO Excitation and Line Energy Distributions in Gas-selected Galaxies
论文作者
论文摘要
虽然排放选择的银河系调查偏向星系群体中最明亮的部分，但吸收选择是一种潜在的无偏星系选择技术，就光度而言。但是，吸收选择的星系的物理特性未充分表征。在这里，我们研究了在阻尼的$α$（DLA）吸收选择的星系中的星际培养基（ISM）中的激发条件。我们介绍了四个高金属吸收选择星系中的CO光谱线能分布（雪橇）的研究，并在中级（$ z \ sim 0.7 $）和高（$ z \ sim 2 $）红移时在先前报道的CO检测中进行了研究。我们发现了这些星系中各种ISM条件的进一步证据。四个星系中的两个显示了与银河系内磁盘相一致的雪橇。有趣的是，这些星系之一是$ z \ sim 2 $，在类似的红移下的主要序列星系低于主要序列星系。 $ z> 2 $的其他两个星系显示出更多激动的ISM条件，其中一个显示了中$ j $（j $ = 3，4 $）的热激发，类似于在这些红移时在两个大型主序列星系中看到的。总体而言，我们发现吸收选择范围会导致各种星系种群。
While emission-selected galaxy surveys are biased towards the most luminous part of the galaxy population, absorption selection is a potentially unbiased galaxy selection technique with respect to luminosity. However, the physical properties of absorption-selected galaxies are not well characterised. Here we study the excitation conditions in the interstellar medium (ISM) in damped Ly$α$ (DLA) absorption-selected galaxies. We present a study of the CO spectral line energy distribution (SLED) in four high-metallicity absorption-selected galaxies with previously reported CO detections at intermediate ($z \sim 0.7$) and high ($z \sim 2$) redshifts. We find further evidence for a wide variety of ISM conditions in these galaxies. Two out of the four galaxies show CO SLEDs consistent with that of the Milky Way inner disk. Interestingly, one of these galaxies is at $z \sim 2$ and has a CO SLED below that of main-sequence galaxies at similar redshifts. The other two galaxies at $z>2$ show more excited ISM conditions, with one of them showing thermal excitation of the mid-$J$ (J$=3, 4$) levels, similar to that seen in two massive main-sequence galaxies at these redshifts. Overall, we find that absorption selection traces a diverse population of galaxies.
