论文标题
标志性UDG DF44周围的球状簇数量是矮星系的预期
The number of globular clusters around the iconic UDG DF44 is as expected for dwarf galaxies
论文作者
论文摘要
越来越多的共识是，绝大多数超湿星系（UDGS）都是矮星系。但是，在其球形群集（GC）系统方面，仍然存在一些UDG。特别是，与一些作者相比，与其出色（或总体）质量的预期相比，某些UDG的GC种群显示出较大的GC种群。在这些特殊的UDG中，昏迷集群中的DF44是最著名的例子之一。据称DF44的GC数量相对较高，$ n_ {gc} = 74^{+18} _ { - 18} $，对于仅$ 3 \ times 10^8 $ $ $ m_ {\ odot} $的出色质量仅为$ 3 \ times 10^8 $ $ $ m_ {\ odot} $，这表明比类似的spellar sellar sellar s seltellar s serlarar sellarar sellar s seltellar。在本文中，我们重新审视了这个数字，与以前的结果相反，找到$ n_ {gc} = 21^{+7} _ { - 9} $，假设GC的分布遵循与星系相同的几何形状。如果我们假设DF44周围的GC是以（投影）圆形对称的方式分布的，并且，如果我们使用不太严格的标准在选择GCS时，我们会发现$ N_ {GC} = 18^{+23} {+23} _ { - 12} $。利用$ m _ {\ rm gc} - m _ {\ rm halo} $关系，此数量的GC表明暗物质晕质量为$ m_ {halo} = 1.1^{+0.4} {+0.4} _ { - 0.5} _ { - 0.5} \ 0.5} \ times 10^{11} m _ iS iS iS iS iS iS iS a is a is a CON CANSS conselation conelution a Conely concelation no contifuntion Anclient an Conelant con Colation a Colation actival a On actival an Conely contival contify notivati DF44基于其速度分散剂，$σ= 33^{+3} _ { - 3} $ km s $^{ - 1} $。我们得出的结论是，在这方面，DF44附近的GC数量是类似恒星质量和DF44的常规矮星系的预期。
There is a growing consensus that the vast majority of ultra-diffuse galaxies (UDGs) are dwarf galaxies. However, there remain a few UDGs that seem to be special in terms of their globular cluster (GC) systems. In particular, according to some authors, certain UDGs exhibit large GC populations when compared to expectations from their stellar (or total) mass. Among these special UDGs, DF44 in the Coma cluster is one of the better-known examples. DF44 has been claimed to have a relatively high number of GCs, $N_{GC}=74^{+18}_{-18}$, for a stellar mass of only $3\times 10^8$ $M_{ \odot }$ which would indicate a much larger dark halo mass than dwarfs of similar stellar mass. In this paper we revisit this number and, contrary to previous results, find $N_{GC}=21^{+7}_{-9}$ assuming that the distribution of the GCs follows the same geometry as the galaxy. If we assume that the GCs around DF44 are distributed in a (projected) circularly symmetric way and, if we use a less strict criterion for the selection of the GCs, we find $N_{GC}=18^{+23}_{-12}$. Making use of the $M_{\rm GC} - M_{\rm halo}$ relation, this number of GCs suggests a dark matter halo mass of $M_{halo}=1.1^{+0.4}_{-0.5} \times 10^{11} M_{\odot}$, a value which is consistent with the expected total mass for DF44 based on its velocity dispersion, $σ=33^{+3}_{-3}$ km s$^{-1}$. We conclude that the number of GCs around DF44 is as expected for regular dwarf galaxies of similar stellar mass and DF44 is not extraordinary in this respect.
