A MegaCam Survey of Outer Halo Satellites. III. Photometric and Structural Parameters
A MegaCam Survey of Outer Halo Satellites. III. Photometric and Structural Parameters
复制标题
DOI：
10.3847/1538-4357/aac16b
复制
发表时间：
2018-06
期刊：
影响因子：
--
通讯作者：
R. Muñoz;P. Côté;F. Santana;M. Geha;J. Simon;Grecco A. Oyarzún;P. Stetson;S. Djorgovski
中科院分区：
文献类型：
--
作者：
R. Muñoz;P. Côté;F. Santana;M. Geha;J. Simon;Grecco A. Oyarzún;P. Stetson;S. Djorgovski
我们提出的结构参数从银河系卫星进行了宽视场均匀成像调查与MegaCam成像仪上的3.6米加拿大-法国-夏威夷望远镜和6.5米麦哲伦-克莱望远镜。我们的调查针对的是“外晕”卫星的无偏样本（即，银河系中心距离大于25 kpc的子结构），包括经典的dSph星系，超暗矮星和遥远的球状星团。我们结合联合收割机的深度，全景gr成像44颗卫星和档案gr成像的14个额外的对象（主要获得的DECam仪器作为暗能量调查的一部分），以测量光度和结构参数为58外晕卫星。这是迄今为止对银河系卫星进行的最大和最统一的分析，约占所有已知外晕卫星的四分之三（58/81 <$72%）。我们使用最大似然方法来拟合四个密度定律，以我们的调查中的每个对象：指数，普卢默，国王，和Sérsic模型。我们系统地检查等密度等值线图和颜色星等图为我们的每个程序对象，提出了与以前的结果进行比较，并列出我们最适合的光度和结构参数，包括椭圆度，位置角，有效半径，Sérsic指数，绝对星等，和表面亮度测量。我们调查外晕卫星的大小-星等图的分布，并表明，目前的样本外晕子结构跨越了很宽的范围内的有效半径，光度和表面亮度，几乎没有证据表明一个干净的分离成星星集群和星系的人口在最微弱的光度和表面亮度。
We present structural parameters from a wide-field homogeneous imaging survey of Milky Way satellites carried out with the MegaCam imagers on the 3.6 m Canada–France–Hawaii Telescope and 6.5 m Magellan-Clay telescope. Our survey targets an unbiased sample of “outer halo” satellites (i.e., substructures having galactocentric distances greater than 25 kpc) and includes classical dSph galaxies, ultra-faint dwarfs, and remote globular clusters. We combine deep, panoramic gr imaging for 44 satellites and archival gr imaging for 14 additional objects (primarily obtained with the DECam instrument as part of the Dark Energy Survey) to measure photometric and structural parameters for 58 outer halo satellites. This is the largest and most uniform analysis of Milky Way satellites undertaken to date and represents roughly three-quarters (58/81 ≃ 72%) of all known outer halo satellites. We use a maximum-likelihood method to fit four density laws to each object in our survey: exponential, Plummer, King, and Sérsic models. We systematically examine the isodensity contour maps and color–magnitude diagrams for each of our program objects, present a comparison with previous results, and tabulate our best-fit photometric and structural parameters, including ellipticities, position angles, effective radii, Sérsic indices, absolute magnitudes, and surface brightness measurements. We investigate the distribution of outer halo satellites in the size–magnitude diagram and show that the current sample of outer halo substructures spans a wide range in effective radius, luminosity, and surface brightness, with little evidence for a clean separation into star cluster and galaxy populations at the faintest luminosities and surface brightnesses.