AGC198606: A gas-bearing dark matter minihalo?
AGC198606: A gas-bearing dark matter minihalo?
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AGC198606：含有气体的暗物质迷你晕？
DOI：
10.1051/0004-6361/201425211
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
R. Muñoz
中科院分区：
文献类型：
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作者：
Elizabeth A. K. Adams;Y. Faerman;W. Janesh;S. Janowiecki;T. Oosterloo;K. Rhode;R. Giovanelli;M. Haynes;J. Salzer;A. Sternberg;J. Cannon;R. Muñoz
我们展示了AGC198606的Westerbork合成射电望远镜对中性氢（HI）的成像观测，这是在ALFALFA 21cm巡天中发现的一个HI云。这个天体特别值得注意，因为它位于距离含气体的超暗矮星系狮子座T 16公里/秒和1.2度的地方，同时具有相似的HI线宽和大约两倍的通量密度。在5x10^18原子cm^-2水平上，HI成像观察显示出光滑、未受干扰的HI形态，其完整范围为23‘x16’。AGC198606的速度场呈有序运动，梯度为~25 km/s，横跨~20′。全球速度色散为9.3 km/s，没有窄谱分量的证据。没有检测到与AGC198606对应的光器件。AGC198606的距离是未知的，我们考虑了几种不同的情况：与狮子座T的物理关联，根据Faerman等人（2013）的模型，距离约150 kpc的小晕，以及银河系晕中的云。在420 kpc的距离上，AGC198606的HI质量为6.2x10^5 Msun， HI半径为1.4 kpc， HI范围内的动态质量为1.5x10^8 Msun。
We present neutral hydrogen (HI) imaging observations with the Westerbork Synthesis Radio Telescope of AGC198606, an HI cloud discovered in the ALFALFA 21cm survey. This object is of particular note as it is located 16 km/s and 1.2 degrees from the gas-bearing ultra-faint dwarf galaxy Leo T while having a similar HI linewidth and approximately twice the flux density. The HI imaging observations reveal a smooth, undisturbed HI morphology with a full extent of 23'x16' at the 5x10^18 atoms cm^-2 level. The velocity field of AGC198606 shows ordered motion with a gradient of ~25 km/s across ~20'. The global velocity dispersion is 9.3 km/s with no evidence for a narrow spectral component. No optical counterpart to AGC198606 is detected. The distance to AGC198606 is unknown, and we consider several different scenarios: physical association with Leo T, a minihalo at a distance of ~150 kpc based on the models of Faerman et al. (2013), and a cloud in the Galactic halo. At a distance of 420 kpc, AGC198606 would have an HI mass of 6.2x10^5 Msun, an HI radius of 1.4 kpc, and a dynamical mass within the HI extent of 1.5x10^8 Msun.