SEARCHING FOR OPTICAL COUNTERPARTS TO ULTRA-COMPACT HIGH VELOCITY CLOUDS: POSSIBLE DETECTION OF A COUNTERPART TO AGC 198606
SEARCHING FOR OPTICAL COUNTERPARTS TO ULTRA-COMPACT HIGH VELOCITY CLOUDS: POSSIBLE DETECTION OF A COUNTERPART TO AGC 198606
复制标题
寻找超紧凑高速云的光学对应物：可能检测到 AGC 198606 的对应物
DOI：
10.1088/0004-637x/811/1/35
复制
发表时间：
2015
期刊：
影响因子：
--
通讯作者：
R. Muñoz
中科院分区：
文献类型：
--
作者：
W. Janesh;K. Rhode;J. Salzer;S. Janowiecki;E. Adams;M. Haynes;R. Giovanelli;J. Cannon;R. Muñoz
我们报告了由阿雷西博遗产快速阿尔法(紫花苜蓿)嗨调查发现的获得超致密高速云(UCHVC)光学成像的活动的初步结果。UCHVC具有与其在局部体积中属于低质量矮小星系一致的属性，但没有确定的光学对应物。我们正在使用WIYN 3.5米望远镜来拍摄这些天体的图像，并寻找相关的恒星群。在这里，我们介绍了我们的观测策略和方法，以寻找与UCHVCs相对应的已分辨恒星。我们结合了仔细的测光技术、色度滤镜和空间平滑技术来搜索g波段和i波段图像中的恒星密度过高。我们还进行统计测试，以量化检测到的密度过高是真实存在的可能性，而不是震源的偶然叠加。我们将该方法应用于两个天体的WIYN成像：LEOP，一个由紫花苜蓿发现的UCHVC，被证明是一个在局部体积中形成恒星的矮星系；以及AGC198606，一个在位置和速度上接近局部群矮星系的紫花苜蓿源。将搜索方法应用到LEOP数据中，可以对该星系的恒星总数产生明确的探测(>；99%的置信度)。将该方法应用于AGC 198606成像，可以从AGC 198606‘S Hi分布的质心和Hi盘内探测到位于∼2.5arcmin的光学对应物(92%置信度)。我们估计到恒星对应物的距离为373-393kpc，绝对星等Mi=−4.67±0.09，高与恒星的质量比为∼45-110。
We report initial results from a campaign to obtain optical imaging of Ultra Compact High Velocity Clouds (UCHVCs) discovered by the Arecibo Legacy Fast ALFA (ALFALFA) Hi survey. UCHVCs have properties consistent with their being low-mass dwarf galaxies in the Local Volume, but do not have identified optical counterparts. We are using the WIYN 3.5 m telescope to image these objects and search for an associated stellar population. Here we present our observational strategy and method for searching for resolved stellar counterparts to the UCHVCs. We combine careful photometry, a color–magnitude filter, and spatial smoothing techniques to search for stellar overdensities in the g- and i-band images. We also run statistical tests to quantify the likelihood that detected overdensities are real and not chance superpositions of sources. We demonstrate the method by applying it to WIYN imaging of two objects: Leo P, a UCHVC discovered by ALFALFA and shown to be a star-forming dwarf galaxy in the Local Volume and AGC 198606, an ALFALFA source near in position and velocity to the Local Group dwarf galaxy Leo T. Applying the search method to the Leo P data yields an unambiguous detection (>99% confidence) of the galaxy’s stellar population. Applying the method to the AGC 198606 imaging yields a possible detection (92% confidence) of an optical counterpart located ∼2.5 arcmin from the centroid of AGC 198606's Hi distribution and within the Hi disk. We estimate a distance to the stellar counterpart of 373–393 kpc, an absolute magnitude Mi = −4.67 ± 0.09, and an Hi-to-stellar mass ratio of ∼45–110.