论文标题
原型超湿银河系，蜻蜓44，不是一种黑暗的银河系
The Archetypal Ultra-Diffuse Galaxy, Dragonfly 44, is not a Dark Milky Way
论文作者
论文摘要
由于超扩散星系（UDGS）的特性奇特，因此了解其起源是一个重大挑战。先前的X射线研究表明，大部分UDG缺乏大量的X射线发射，这意味着它们驻留在低质量的暗物质光环中。与其他观察性和理论研究一致的结果指出，大多数UDG属于矮星系。但是，据信UDG的一部分占据了大量的球状簇（GC），这表明了大量的暗物质光环。反过来，这暗示了某些UDG可能失败了$ l _ {\ star} $ galaxies。在这项工作中，我介绍了两种原型UDG，Draginfly 44和DF X1的Chandra和XMM-Newton观察结果，并且根据X射线发射构成了X射线发射的限制，这些发射来自热气体排放以及来自GCS中的低质量X射线二元组的人群。在X射线中，蜻蜓44和DF X1均未发现。 X射线排放的上限排除了这些星系驻留在巨大的可能性（$ m _ {\ rm vir} \ gtrsim 5 \ times10^{11} {11} \ \ \ \ rm {m _ {\ odot}}} $的可能性，暗示它们没有失败，表明他们没有失败。这些结果表明，即使这些标志性的UDG类似于$ M _ {\ rm vir} \ Lessim 10^{11} \ \ rm {m _ {\ odot}} $，暗示UDGS代表单个星系人群。
Due to the peculiar properties of ultra-diffuse galaxies (UDGs), understanding their origin presents a major challenge. Previous X-ray studies demonstrated that the bulk of UDGs lack substantial X-ray emission, implying that they reside in low-mass dark matter halos. This result, in concert with other observational and theoretical studies, pointed out that most UDGs belong to the class of dwarf galaxies. However, a subset of UDGs is believed to host a large population of globular clusters (GCs), which is indicative of massive dark matter halos. This, in turn, hints that some UDGs may be failed $L_{\star}$ galaxies. In this work, I present Chandra and XMM-Newton observations of two archetypal UDGs, Dragonfly 44 and DF X1, and I constrain their dark matter halo mass based on the X-ray emission originating from hot gaseous emission and from the population of low-mass X-ray binaries residing in GCs. Both Dragonfly 44 and DF X1 remain undetected in X-rays. The upper limits on the X-ray emission exclude the possibility that these galaxies reside in massive ($M_{\rm vir} \gtrsim 5\times10^{11} \ \rm{M_{\odot}}$) dark matter halos, suggesting that they are not failed $L_{\star}$ galaxies. These results demonstrate that even these iconic UDGs resemble to dwarf galaxies with $M_{\rm vir} \lesssim 10^{11} \ \rm{M_{\odot}}$, implying that UDGs represent a single galaxy population.
