对天炉座星系团的ATCA HI盲观测：HI探测的特性
A blind ATCA HI survey of the Fornax galaxy cluster: properties of the HI detections
摘要：
我们提出了第一个干涉仪盲HI调查的天炉座星系团，其中涵盖了15度$^2$的集群$R_{vir}$。该测量的分辨率为67“x95”和6.6 km $s^{-1}$，3 $σ$灵敏度为N（HI）~ 2x 10 $^{19}$ cm $^{-2}$和MHI 2x 10 $^7$ M $_\odot$。我们在200个光谱确认的天炉座星系团成员中探测到16个星系。检测涵盖HI质量的约3个数量级，从8 × 10 $^6$到1.5 × 10 $^{10}$ M $_\odot$。它们避开了星团的中心，在天空和投影相空间中的维里化区域，表明它们是最近到达的，在天炉座，HI在一个交叉时间内丢失，~2 Gyr。这些星系的一半表现出干扰HI形态，包括几个案件的不对称性，尾巴，HI和光学中心之间的偏移，和一个截断HI光盘的情况下，这表明他们一直在相互作用内或在前往天炉座的路上。我们的HI探测是HI贫穷和形成恒星的速度低于非星系团星系在相同的$M_\star$范围。低质量的星系在整个落入星系团的过程中受到更强烈的影响。天炉座星系的MHI/ $M_\star$比值与室女座星系团相当。在固定的$M_\star$，我们的HI检测遵循MHI和恒星形成率之间的非集群关系，我们认为，这意味着到目前为止，他们已经失去了他们的HI的时间尺度$\gtrsim$ 1-2 Gyr。在星团内部更深的地方，HI的移除可能进行得更快，这一点已经被一群HI未被探测到但H $_2$探测到的恒星形成星系所证实。基于ALMA的数据，我们发现一个大的分散在H $_2$ -HI质量比，有几个星系显示出异常高的比例，这可能是由于更快的HI去除。我们确定了一个可能的相互作用星系的HI丰富的子群主导的NGC 1365，其中预处理是likey已经发生。
英文摘要：
We present the first interferometric blind HI survey of the Fornax galaxy cluster, which covers an area of 15 deg$^2$ out to the cluster $R_{vir}$. The survey has a resolution of 67''x95'' and 6.6 km$s^{-1}$ with a 3$σ$ sensitivity of N(HI)~2x10$^{19}$ cm$^{-2}$ and MHI 2x10$^7$ M$_\odot$. We detect 16 galaxies out of 200 spectroscopically confirmed Fornax cluster members. The detections cover ~3 orders of magnitude in HI mass, from 8x10$^6$ to 1.5x10$^{10}$ M$_\odot$. They avoid the central, virialised region of the cluster both on the sky and in projected phase-space, showing that they are recent arrivals and that, in Fornax, HI is lost within a crossing time, ~2 Gyr. Half of these galaxies exhibit a disturbed HI morphology, including several cases of asymmetries, tails, offsets between HI and optical centres, and a case of a truncated HI disc suggesting that they have been interacting within or on their way to Fornax. Our HI detections are HI-poorer and form stars at a lower rate than non-cluster galaxies in the same $M_\star$ range. Low mass galaxies are more strongly affected throughout their infall towards the cluster. The MHI/$M_\star$ ratio of Fornax galaxies is comparable to that in the Virgo cluster. At fixed $M_\star$, our HI detections follow the non-cluster relation between MHI and the star formation rate, and we argue that this implies that so far they have lost their HI on a timescale $\gtrsim$1-2 Gyr. Deeper inside the cluster HI removal is likely to proceed faster, as confirmed by a population of HI-undetected but H$_2$-detected star-forming galaxies. Based on ALMA data, we find a large scatter in H$_2$-to-HI mass ratio, with several galaxies showing an unusually high ratio that is probably caused by faster HI removal. We identify an HI-rich subgroup of possible interacting galaxies dominated by NGC 1365, where pre-processing is likey to have taken place.
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