THE DEARTH OF NEUTRAL HYDROGEN IN GALACTIC DWARF SPHEROIDAL GALAXIES
THE DEARTH OF NEUTRAL HYDROGEN IN GALACTIC DWARF SPHEROIDAL GALAXIES
复制标题
银矮星系中中性氢的缺乏
DOI：
10.1088/2041-8205/795/1/l5
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
J. Aguirre
中科院分区：
文献类型：
--
作者：
K. Spekkens;N. Urbancic;B. Mason;B. Willman;J. Aguirre
我们给出了15个银河系矮小球状星系(DSphs)恒星半光椭圆内中性氢(H I)含量的新上限，这些数据来自于绿岸望远镜的定点观测以及阿雷西博-L波段的快速阿尔法观测和银河系全天巡天数据。所有的限制都比之前报道的值更严格，GBT的限制比文献中的限制提高了23倍。通过对V波段光度LV和动力学质量Mdyn进行归一化，我们发现并且与银晕中的位置无关。将这些相对H I含量与麦康奈奇编制的局域群和邻近矮星的含量进行比较，我们发现银河系dSphs是极度贫气的。因此，我们的H I上限提供了迄今为止最清晰的图像，说明了局部体积矮星中H I含量与环境的相关性。如果冲压剥离解释了这些系统中H I的缺乏，那么相对大质量的银河系中的轨道有利于外晕dSph Leo I，而Leo II和Canes Venatii I在过去曾有过一次中心附近的通道。对于德拉科和小熊座来说，在震心通道之间通过恒星质量损失积累的星际介质质量超过了∼30倍。在Ursa Minor中，这意味着要么这种材料不处于原子相，要么另一种机制在更短的时间尺度上清除了回收的气体。
We present new upper limits on the neutral hydrogen (H i) content within the stellar half-light ellipses of 15 Galactic dwarf spheroidal galaxies (dSphs), derived from pointed observations with the Green Bank Telescope (GBT) as well as Arecibo L-band Fast ALFA survey and Galactic All-Sky Survey data. All of the limits are more stringent than previously reported values, and those from the GBT improve upon constraints in the literature by a median factor of 23. Normalizing by V-band luminosity LV and dynamical mass Mdyn, we find and , irrespective of location in the Galactic halo. Comparing these relative H i contents to those of the Local Group and nearby neighbor dwarfs compiled by McConnachie, we find that the Galactic dSphs are extremely gas-poor. Our H i upper limits therefore provide the clearest picture yet of the environmental dependence of the H i content in Local Volume dwarfs. If ram pressure stripping explains the dearth of H i in these systems, then orbits in a relatively massive Milky Way are favored for the outer halo dSph Leo I, while Leo II and Canes Venatici I have had a pericentric passage in the past. For Draco and Ursa Minor, the interstellar medium mass that should accumulate through stellar mass loss in between pericentric passages exceeds by a factor of ∼30. In Ursa Minor, this implies that either this material is not in the atomic phase, or that another mechanism clears the recycled gas on shorter timescales.
DOI：
10.1086/590336
发表时间：
2008-05
期刊：
The Astrophysical Journal
影响因子：
--
作者：
N. Martin;J. D. de Jong;H. Rix
通讯作者：
N. Martin;J. D. de Jong;H. Rix