来自ALFALFA调查I的早型镓的HI含量。室女星系团中已编目的HI源
The HI content of Early-Type Galaxies from the ALFALFA survey I. Catalogued HI sources in the Virgo cluster
摘要：
目的：我们正在使用阿雷西博遗产快速ALFA调查（ALCAFA），这是覆盖17%的天空在21厘米，研究早期型星系（ETG）的HI含量在一个公正的方式。目的是全面了解ETG的热，暖，冷ISM，作为星系质量和环境的函数，了解其起源和命运，并将其与这些物体的形成和演化历史联系起来。方法：本文涉及我们的研究的第一部分，这是专门为8-16度。在室女星系团的十月带。在这个天区中，我们用室女星系团星表（VCC）定义了一个939 ETG的光学样品，其中457个比VCC完全极限（B_T=18.0）亮。我们已经将这个光学样品与从ALUCHFA检测到的HI源的目录相关联。结果：在389例B_T<=18.0的VCC ETG中，在1度范围外。在M87周围的HI探测较差的区域，并对VCC星系的背景污染进行了修正，没有已知的径向速度，只有9个星系（2.3%）在HI中被探测到，对于矮ETG和巨ETG，HI的完整性极限分别为3.5 x 10^7 Mo和7.6 x 10^7 Mo。此外，还检测到具有较暗幅度的4 VCC ETG。我们的HI检测率低于先前声称的。大多数检测到的ETG似乎有特殊的形态，并位于附近的边缘的室女星系团。结论：我们的初步结论是，ETG星系团包含非常少的中性气体，除了少数特殊的矮星系在ETG分类的边缘和非常少的较大的ETG，那里的冷气体可能有一个最近的外部起源。
英文摘要：
Aims: We are using the Arecibo Legacy Fast ALFA survey (ALFALFA), which is covering 17% of the sky at 21 cm, to study the HI content of Early-Type galaxies (ETG) in an unbiased way. The aim is to get an overall picture of the hot, warm and cold ISM of ETG, as a function of galaxy mass and environment, to understand its origin and fate, and to relate it to the formation and evolution history of these objects. Methods: This paper deals with the first part of our study, which is devoted to the 8-16 deg. declination strip in the Virgo cluster. In this sky region, using the Virgo Cluster Catalogue (VCC), we have defined an optical sample of 939 ETG, 457 of which are brighter than the VCC completeness limit at B_T=18.0. We have correlated this optical sample with the catalogue of detected HI sources from ALFALFA. Results: Out of the 389 ETG from the VCC with B_T<=18.0, outside the 1 deg. region of poor HI detection around M87, and corrected for background contamination of VCC galaxies without a known radial velocity, only 9 galaxies (2.3%) are detected in HI with a completeness limit of 3.5 and 7.6 x 10^7 Mo of HI for dwarf and giant ETG, respectively. In addition 4 VCC ETG with fainter magnitudes are also detected. Our HI detection rate is lower than previously claimed. The majority of the detected ETG appear to have peculiar morphology and to be located near the edges of the Virgo cluster. Conclusions: Our preliminary conclusion is that cluster ETG contain very little neutral gas, with the exceptions of a few peculiar dwarf galaxies at the edge of the ETG classification and of very few larger ETG, where the cold gas could have a recent external origin.
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