We present the first comprehensive archival study of the X-ray properties of ultracompact dwarf (UCD) galaxies, with the goal of identifying weakly-accreting central black holes in UCDs. Our study spans 578 UCDs distributed across thirteen different host systems, including clusters, groups, fossil groups, and isolated galaxies. Of the 336 spectroscopically-confirmed UCDs with usable archival Chandra imaging observations, 21 are X-ray-detected. Imposing a completeness limit of $L_X>2\times10^{38}$ erg s$^{-1}$, the global X-ray detection fraction for the UCD population is $\sim3\%$. Of the 21 X-ray-detected UCDs, seven show evidence of long-term X-ray time variability on the order of months to years. X-ray-detected UCDs tend to be more compact than non-X-ray-detected UCDs, and we find tentative evidence that the X-ray detection fraction increases with surface luminosity density and global stellar velocity dispersion. The X-ray emission of UCDs is fully consistent with arising from a population of low-mass X-ray binaries (LMXBs). In fact, there are fewer X-ray sources than expected using a naive extrapolation from globular clusters. Invoking the fundamental plane of black hole activity for SUCD1 near the Sombrero galaxy, for which archival Jansky Very Large Array imaging at 5 GHz is publicly available, we set an upper limit on the mass of a hypothetical central black hole in that UCD to be $\lesssim10^5M_{\odot}$. While the majority of our sources are likely LMXBs, we cannot rule out central black holes in some UCDs based on X-rays alone, and so we address the utility of follow-up radio observations to find weakly-accreting central black holes.
A Detailed Archival CHANDRA Study of the Young Core-Collapse Supernova Remnant 1E 0102.2-7219 in the Small Magellanic Cloud
我们提出了一个档案钱德拉研究的富氧超新星遗迹（SNR）1 E 0102.2-7219在小麦哲伦星云。基于深$\sim$ 265 ks档案钱德拉数据，我们进行了详细的空间分辨光谱分析1 E 0102.2-7219。我们的目标是以前所未有的细节揭示这个遗迹的空间和化学结构。根据我们对沿1 E 0102.2-7219的9个不同方位角方向提取的区域光谱的分析，O、Ne和Mg丰度的径向分布表明，在距离SNR X射线发射几何中心$\sim$ 5-5.5 pc处存在接触不连续性。我们发现，富含金属的喷出物气体进一步向外延伸在西部和西南部比其他方向的SNR。喷出物的平均O/Ne、O/Mg和Ne/Mg丰度比与$\sim 40 M_\odot$祖先爆炸的核合成产物似乎一致。我们估计1 E 0102.2-7219的Sedov年龄上限为$\sim 3500$年，爆炸能量上限为$\sim 1.8\times10^{51}$尔格。我们讨论的影响，我们的结果的几何结构的残余，其拱星介质和祖星的性质。我们的研究结果不适合一个简单的图片的反向冲击发射从一个球壳状喷出物气体均匀分布的金属丰度和幂律密度沿半径的SNR。
Ne and Fe abundances in the ISM: Archival Study of Fe-L and Ne-K edges in Chandra and XMM-Newton
University of Michigan（密歇根大学）；European Space Agency, European Space Research and Technology Center（欧洲空间局，欧洲空间研究与技术中心）；Rochester Institute of Technology（罗切斯特理工学院）
A Deep Chandra View of Abell 2597: Bubbles, Shocks, Cold Fueling, and a Plasma Depletion Layer
University of Manitoba（曼尼托巴大学）；U.S. Naval Research Laboratory（美国海军研究实验室）；National Centre for Nuclear Research（国家核研究中心）；Institute of Astronomy, University of Cambridge（剑桥大学天文研究所）；Tata Institute for Fundamental Research（塔塔基础研究所）；NASA Goddard Space Flight Center（NASA戈达德太空飞行中心）；ICRAR, University of Western Australia（西澳大利亚大学星际计算与相对论天体物理研究中心）；Ashoka University（阿肖卡大学）
Analysis of the 3C445 Soft X-ray Spectrum as Observed by Chandra high-energy gratings
我们提出了一个详细的分析软X射线发射的3C 445使用档案钱德拉HETG光谱。高电离的H-和He-类Mg，Si和S线，以及一个解决的低电离Si K $α$线，在高分辨率光谱检测。类氦三重态的Mg和Si被分解成单独的线，并且计算出的R比表明发射极的高密度。低的G值表明谱线来自碰撞电离等离子体。然而，在光谱中的一个解决窄Ne X RRC功能的检测似乎更喜欢一个光电离环境。光谱随后建模与光电离模型，并与碰撞模型的结果进行了比较。通过对光谱的详细分析，我们排除了这些发射线的碰撞起源。一个单组分光电离模型提供了一个很好的适合的发射功能。最佳拟合参数为log $ξ$ = $3.3^{+0.4}_{-0.3}$ erg cm s $^{-1}$、$n_{H}$ = $5^{+15}_{-4.5}\times10^{10}$ cm $^{-3}$和$N_{H}$ = $2.5^{+3.8}_{-1.7}\times10^{20}$ cm $^{-2}$。根据计算的发射体高密度、测量的发射谱线速度宽度和推断的径向距离（6 $\times$ $10^{14}$ - 8 $\times$ $10^{15}$ cm），我们认为发射谱线来自物质，位于宽线区（BLR）。
