A Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE)
A Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE)
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DOI：
10.1051/0004-6361/201732373
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发表时间：
2018-01
影响因子：
6.5
通讯作者：
M. Fossati;J. Mendel;A. Boselli;J. Cuillandre;B. Vollmer;S. Boissier;G. Consolandi;L. Ferrarese-L.-Ferrar
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文献类型：
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作者：
M. Fossati;J. Mendel;A. Boselli;J. Cuillandre;B. Vollmer;S. Boissier;G. Consolandi;L. Ferrarese-L.-Ferrar
处女座环境调查追踪电离气体排放 (VESTIGE) 是一项盲窄带 Hα + [NII] 成像调查，使用加拿大-法国-夏威夷望远镜的 MegaCam 进行。在 2016 年春季进行的试点观测中，我们观察到了 NGC 4330，这是一颗中等质量 (M* ≃ 109.8 M⊙) 的边缘恒星形成螺旋，目前落入室女座星团的核心。虽然之前的 Hα 观测显示星系盘外部存在电离气体结的块状复合体，但新的深层观测揭示了表面亮度约 10 kpc 的低尾部，呈现出奇特的丝状结构。这些细丝彼此非常平行，清楚地表明了处女座势中星系的运动方向。受检测这些表明正在进行气体剥离的特征的启发，我们使用 ESO 甚大望远镜的 FORS2 仪器收集了从远紫外到远红外和深光学长缝光谱的 15 个波段的光度测定文献。使用新开发的蒙特卡罗代码，结合光谱学和光度测量，我们重建了沿星系主轴的孔径中的恒星形成历史。我们的结果已经根据 CIGALE 的输出进行了验证，CIGALE 是之前用于类似研究的拟合代码。我们发现淬火事件开始时半径存在明显的由外向内梯度：最外层半径在约 500 Myr 前被剥离，而在最后 100 Myr 中剥离达到距中心 5 kpc 的内部。目前，半径更小的区域仍在形成由 HI 和 H2 气体推动的恒星。与局部宇宙中淬灭时间尺度的统计研究相比，我们发现冷气体的冲压压力剥离是减少星系落入大质量星团的转变时间的有效机制。未来对 VESTIGE 观测到的室女座星团中所有活跃星系的系统研究将把这些结果扩展到一个强大的统计框架。
The Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE) is a blind narrow-band Hα + [NII] imaging survey carried out with MegaCam at the Canada-France-Hawaii Telescope. During pilot observations taken in the spring of 2016 we observed NGC 4330, an intermediate mass (M* ≃ 109.8 M⊙) edge-on star forming spiral currently falling into the core of the Virgo cluster. While previous Hα observations showed a clumpy complex of ionised gas knots outside the galaxy disc, new deep observations revealed a low surface brightness ~10 kpc tail exhibiting a peculiar filamentary structure. The filaments are remarkably parallel to one another and clearly indicate the direction of motion of the galaxy in the Virgo potential. Motivated by the detection of these features which indicate ongoing gas stripping, we collected literature photometry in 15 bands from the far-UV to the far-IR and deep optical long-slit spectroscopy using the FORS2 instrument at the ESO Very Large Telescope. Using a newly developed Monte Carlo code that jointly fits spectroscopy and photometry, we reconstructed the star formation histories in apertures along the major axis of the galaxy. Our results have been validated against the output of CIGALE, a fitting code which has been previously used for similar studies. We found a clear outside-in gradient with radius of the time when the quenching event started: the outermost radii were stripped ~500 Myr ago, while the stripping reached the inner 5 kpc from the centre in the last 100 Myr. Regions at even smaller radii are currently still forming stars fueled by the presence of HI and H2 gas. When compared to statistical studies of the quenching timescales in the local Universe we find that ram pressure stripping of the cold gas is an effective mechanism to reduce the transformation times for galaxies falling into massive clusters. Future systematic studies of all the active galaxies observed by VESTIGE in the Virgo cluster will extend these results to a robust statistical framework.