THE ALFALFA “ALMOST DARKS” CAMPAIGN: PILOT VLA HI OBSERVATIONS OF FIVE HIGH MASS-TO-LIGHT RATIO SYSTEMS
THE ALFALFA “ALMOST DARKS” CAMPAIGN: PILOT VLA HI OBSERVATIONS OF FIVE HIGH MASS-TO-LIGHT RATIO SYSTEMS
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苜蓿“近乎黑暗”活动：VLA HI 飞行员对五个高质光比系统的观测
DOI：
10.1088/0004-6256/149/2/72
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
P. Troischt
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文献类型：
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作者：
J. Cannon;Charlotte P. Martinkus;L. Leisman;M. Haynes;E. Adams;R. Giovanelli;G. Hallenbeck;S. Janowiecki;Michael Jones;G. J'ozsa;R. Koopmann;Nathan S. Nichols;E. Papastergis;K. Rhode;J. Salzer;P. Troischt
我们展示了由ALFALFA星系外巡天发现的五个源的新的甚大阵列（VLA） H - i谱线成像。这些目标是从一个更大的系统样本中提取的，这些系统在ALFALFA处理过程中没有被唯一地识别为光学对应物，因此具有异常高的H质量和光比。候选的“几乎暗”天体可分为四大类：(1)与H星相邻的天体可能是潮汐起源的；(2)似乎是由多个H源组成的系统的一部分，但可能不是潮汐源的天体；(3)从附近的ALFALFA H i探测中分离出来的天体，但位于气体贫乏的早型星系附近；(4)明显孤立的源，在~ 400kpc内没有重合红移的目标。在200个物体中，大约75%的物体在α中没有对应的识别对象。40数据库（Haynes et al.）属于第1类（可能是潮汐），不考虑用于综合随访观察。这里展示的试点样本（AGC193953、AGC208602、AGC208399、AGC226178和AGC233638）包含了观测到的前五个源，作为在单碟分辨率下没有容易识别的光学对应物的更大努力的一部分（3.5）。这些天体的质量范围为[7.41 < log(MHi) < 9.51]，质量与b波段光度比为（3 < MHi /LB < 9）。我们将H的总强度和速度场与来自斯隆数字巡天的光学成像和来自GALEX观测档案的紫外成像进行了比较。与VLA的H强度图相比，在斯隆数字巡天成像中，ALFALFA数据中有4个光学对应物不确定或没有光学对应物的源被识别为低表面亮度的光学对应物，并且似乎是在H速度场中有明显有序旋转迹象的星系。其中三个是在远紫外GALEX图像中检测到的，这可能是在过去几百迈内形成恒星的迹象。其中一个来源（AGC208602）可能是潮汐性质的，与NGC 3370群有关。与之前的努力一致，我们在这个有限的样本中没有发现“暗星系”。然而，目前的观测确实揭示了恒星形成受到抑制的复杂来源，突出了观测的困难和综合后续观测的必要性，以了解这些极端天体。
We present new Very Large Array (VLA) H i spectral line imaging of five sources discovered by the ALFALFA extragalactic survey. These targets are drawn from a larger sample of systems that were not uniquely identified with optical counterparts during ALFALFA processing, and as such have unusually high H i mass to light ratios. The candidate “Almost Dark” objects fall into four broad categories: (1) objects with nearby H i neighbors that are likely of tidal origin; (2) objects that appear to be part of a system of multiple H i sources, but which may not be tidal in origin; (3) objects isolated from nearby ALFALFA H i detections, but located near a gas-poor early type galaxy; (4) apparently isolated sources, with no object of coincident redshift within ∼400 kpc. Roughly 75% of the 200 objects without identified counterparts in the α.40 database (Haynes et al. ) fall into category 1 (likely tidal), and were not considered for synthesis follow-up observations. The pilot sample presented here (AGC193953, AGC208602, AGC208399, AGC226178, and AGC233638) contains the first five sources observed as part of a larger effort to characterize H i sources with no readily identifiable optical counterpart at single dish resolution (3.′5). These objects span a range of H i mass [7.41 < log(MHi ) < 9.51] and H i mass to B-band luminosity ratios (3 < MHi /LB < 9). We compare the H i total intensity and velocity fields to optical imaging drawn from the Sloan Digital Sky Survey and to ultraviolet imaging drawn from archival GALEX observations. Four of the sources with uncertain or no optical counterpart in the ALFALFA data are identified with low surface brightness optical counterparts in Sloan Digital Sky Survey imaging when compared with VLA H i intensity maps, and appear to be galaxies with clear signs of ordered rotation in the H i velocity fields. Three of these are detected in far-ultraviolet GALEX images, a likely indication of star formation within the last few hundred Myrs. One source (AGC208602) is likely tidal in nature, associated with the NGC 3370 group. Consistent with previous efforts, we find no “dark galaxies” in this limited sample. However, the present observations do reveal complex sources with suppressed star formation, highlighting both the observational difficulties and the necessity of synthesis follow-up observations to understand these extreme objects.
斯隆数字巡天第十次数据发布：来自 SDSS-III 阿帕奇点天文台银河演化实验的首个光谱数据
DOI：
10.1088/0067-0049/211/2/17
发表时间：
2014
期刊：
The Astrophysical Journal Supplement Series
影响因子：
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作者：
Ahn C
通讯作者：
Ahn C