广角阿雷西博室女座河外巡天：II. WAVES南区的中性氢属性与环境特征研究
Widefield Arecibo Virgo Extragalactic Survey: II. Characterizing the HI properties and environment of the WAVES South region
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中文总结 AI 辅助
该研究通过分析WAVES南区HI数据，对比VC1区域，发现WAVES南区HI探测比例更低，更趋演化，还发现光学暗气体云与“蓝 blob”可能存在演化关联。
中文摘要 AI 辅助
背景：星系团是极端环境，与热的星系际介质的相互作用会驱动星系快速演化，这些过程可形成光学暗气体云，此前已在室女座星系团及其他星系团中观测到该现象。目标：研究室女座星系团两个相邻大区域内中性氢（HI）的分布与属性，以理解星系团环境如何影响星系转变，具体考察恒星形成星系与宁静星系的气体含量，搜寻气体流失驱动演化的证据。方法：采用目视与自动源提取方法对21cm HI广角阿雷西博室女座河外巡天（WAVES）南区数据进行编目，结合光学选样本，将WAVES南区的HI属性与此前研究的VC1区域对比；为探测标称探测限以下的气体储库，对WAVES南区、VC1和VC2天区的射电频谱开展堆叠分析。结果：共探测到56个HI源，其中值均方根（rms）噪声为0.8 mJy，包括50个星系、2个气体云（其中1个为光学暗气体云）以及ALFALFA室女座7复合体；结果显示WAVES南区的探测比例显著低于VC1区域；堆叠分析在0.080 mJy的rms噪声下未探测到新的HI信号，最大堆叠天体数量为157个，来自WAVES南区、VC1和VC2。结论：较低的HI探测比例表明WAVES南区是比VC1区域更动力学弛豫、演化程度更高的环境；一小部分早型星系中残留HI的存在支持了通过环境剥离发生矮不规则星系到矮椭圆星系转变的模型；最后，注意到光学暗气体云与近期发现的“蓝 blob”之间可能存在演化关联。
英文摘要
Context. Galaxy clusters are extreme environments where interactions with the hot intracluster medium drive rapid galaxy evolution. These processes can result in the formation of optically dark gas clouds, as previously observed in Virgo and other clusters. Aims. We investigate the distribution and properties of neutral hydrogen (HI) in two large adjoining regions of the Virgo cluster to understand how the cluster environment influences galaxy transformation. Specifically, we examine the gas content of both star-forming and quiescent populations and search for evidence of gas-loss driven evolution. Methods. We cataloged the 21cm HI Widefield Arecibo Virgo Extragalactic Survey (WAVES) South data using visual and automatic source extraction methods. By combining these results with an optically selected sample, we compared the HI properties of WAVES South with the previously studied VC1 region. To probe gas reservoirs below the nominal detection limit, we performed a stacking analysis of radio spectra across the WAVES South, VC1 and VC2 footprints. Results. We detected 56 HI sources with a median root mean square (rms) noise of 0.8 mJy, including 50 galaxies, two gas clouds (one being optically dark), and the ALFALFA Virgo 7 complex. Our results reveal a significantly lower detection fraction in WAVES South compared to the VC1 region. Stacking showed no new HI detection at a 0.080 mJy rms with a maximum of 157 stacked objects from WAVES South, VC1, and VC2. Conclusions. The lower HI detection fraction suggests that WAVES South is a more dynamically relaxed and evolved environment than the VC1 region. The presence of residual HI in a small subset of early-type galaxies supports a model of dwarf irregular to dwarf elliptical transformation via environmental stripping. Finally, we note a possible evolutionary link between optically dark clouds and recently discovered "blue blobs."
