Resolving the Galaxies within a Giant Lya Nebula: Witnessing the Formation of a Galaxy Group?
Moire K. M. Prescott, Arjun Dey, Mark Brodwin, Frederic H. Chaffee, Vandana Desai, Peter Eisenhardt, Emeric Le Floc'h, Buell T. Jannuzi, Nobunari Kashikawa, Yui… 展开作者
Moire K. M. Prescott, Arjun Dey, Mark Brodwin, Frederic H. Chaffee, Vandana Desai, Peter Eisenhardt, Emeric Le Floc'h, Buell T. Jannuzi, Nobunari Kashikawa, Yuichi Matsuda, B. T. Soifer
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Accepted to ApJ after minor revision; 33 pages in emulateapj format, 21 figures, 4 tables
Detailed analysis of the substructure of Lya nebulae can put important constraints on the physical mechanisms at work and the properties of galaxies forming within them. Using high resolution HST imaging of a Lya nebula at z~2.656, we have taken a census of the compact galaxies in the vicinity, used optical/near-infrared colors to select system members, and put constraints on the morphology of the spatially-extended emission. The system is characterized by (a) a population of compact, low luminosity (~0.1 L*) sources --- 17 primarily young, small (Re~1-2 kpc), disky galaxies including an obscured AGN --- that are all substantially offset (>20 kpc) from the line-emitting nebula; (b) the lack of a central galaxy at or near the peak of the Lya emission; and (c) several nearly coincident, spatially extended emission components --- Lya, HeII, and UV continuum --- that are extremely smooth. These morphological findings are difficult to reconcile with theoretical models that invoke outflows, cold flows, or resonant scattering, suggesting that while all of these physical phenomena may be occurring, they are not sufficient to explain the powering and large extent of Lya nebulae. In addition, although the compact galaxies within the system are irrelevant as power sources, the region is significantly overdense relative to the field galaxy population (by at least a factor of 4). These observations provide the first estimate of the luminosity function of galaxies within an individual Lya nebula system, and suggest that large Lya nebulae may be the seeds of galaxy groups or low-mass clusters.
What is the physical origin of strong Lya emission? II. Gas Kinematics and Distribution of Lya Emitters
本文统计研究了z~2处Lya发射体的速度、星际吸收、星云谱线和气体覆盖率。根据我们的深Keck/LRIS观测，结合Subaru/FMOS计划和文献的光谱数据，我们制作了22个Lya等效宽度（EW）大于50的LAE样本。我们用星云谱线确定的系统红移dv_Lya=234+-9 km s-1来估计Lya的平均速度偏移。使用Kolmogorv-Smirnov检验，我们证实了Hashimoto等人（2013）先前的声明，即LAEs的平均dv_Lya小于LBG的平均dv_Lya。我们的LRIS数据成功地确定蓝移的多个IS吸收线在紫外连续的四个LAEs在个人的基础上。IS吸收线相对于系统红移的平均速度偏移为dv_IS=204 ± 27 km s-1，表明LAE的气体外流速度与典型的LBG相当。因此，LAE的比率R^Lya_ IS = dv_Lya/dv_IS约为1，表明IS介质中中性氢的共振散射对Lya传输的影响较低。我们发现Lya EW和覆盖分数f_c之间存在反相关关系，其中f_c是平均中性氢柱密度N_HI的指标。我们的研究结果支持了NHI是决定Lya发射率的关键量的观点。
Lyman-alpha Blobs Like Company : The Discovery of A Candidate 100 kpc Lyman-alpha Blob Near to A Radio Galaxy with A Giant Lyman-alpha halo, B3 J2330+3927 at z=3.1
