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arXiv 2007.10565astro-ph.GA
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下一代室女星系团调查(NGVS)。XXX。超扩散星系团及其球状星团系统

The Next Generation Virgo Cluster Survey (NGVS). XXX. Ultra-Diffuse Galaxies and their Globular Cluster Systems

Sungsoon Lim, Patrick Côté, Eric W. Peng, Laura Ferrarese, Joel C. Roediger, Patrick R. Durrell, J. Christopher Mihos, Kaixiang Wang, S. D. J. Gwyn, Jean-Charle… 展开作者

Sungsoon Lim, Patrick Côté, Eric W. Peng, Laura Ferrarese, Joel C. Roediger, Patrick R. Durrell, J. Christopher Mihos, Kaixiang Wang, S. D. J. Gwyn, Jean-Charles Cuillandre, Chengze Liu, Rubén Sánchez-Janssen, Elisa Toloba, Laura V. Sales, Puragra Guhathakurta, Ariane Lançon, Thomas H. Puzia

摘要:

利用新一代室女星系团巡天(NGVS)的深空成像,对室女星系团中的超弥散星系(UDG)进行了研究。应用一个新的定义的UDG类的星系标度关系的基础上,我们定义的样本44和26 UDG使用扩张性和限制性的选择标准,分别。我们的UDG样本包括比以前已知的UDG明显更暗的对象:即,一半以上比$\langleμ\rangle_e \sim27.5$ mag arcsec $^{-2}$更暗。室女座核心区域的UDG显示了一些证据,表明它们在结构上与“正常”矮星系不同,但当考虑整个星系团的完整样本时,这种分离就消失了。UDG在空间分布上比其他类似光度的室女座星系更集中,而它们的形态表明,至少有一些UDG的扩散性质是由于星系团环境中的物理过程-如潮汐相互作用或低质量合并。室女座UDG的球状星团(GC)系统具有很宽的比频($S_N$)范围,在固定光度下,平均$S_N$比“正常”室女座矮星高,但平均$S_N$比后发座UDG低。它们的GC主要是蓝色的,在更大质量的UDG中,红色星团的贡献很小。合并的GC光度函数与矮星系中观察到的一致,没有显示出异常发光的证据。它们的形态和GC性质的多样性表明,没有一个单一的过程产生了UDG类中的所有对象。基于现有的证据,我们得出结论,UDG只是那些系统,占据了星系大小和表面亮度分布的延长尾巴。

英文摘要:

We present a study of ultra-diffuse galaxies (UDGs) in the Virgo Cluster based on deep imaging from the Next Generation Virgo Cluster Survey (NGVS). Applying a new definition for the UDG class based on galaxy scaling relations, we define samples of 44 and 26 UDGs using expansive and restrictive selection criteria, respectively. Our UDG sample includes objects that are significantly fainter than previously known UDGs: i.e., more than half are fainter than $\langleμ\rangle_e \sim27.5$ mag arcsec$^{-2}$. The UDGs in Virgo's core region show some evidence for being structurally distinct from "normal" dwarf galaxies, but this separation disappears when considering the full sample of galaxies throughout the cluster. UDGs are more centrally concentrated in their spatial distribution than other Virgo galaxies of similar luminosity, while their morphologies demonstrate that at least some UDGs owe their diffuse nature to physical processes---such as tidal interactions or low-mass mergers---that are at play within the cluster environment. The globular cluster (GC) systems of Virgo UDGs have a wide range in specific frequency ($S_N$), with a higher mean $S_N$ than "normal" Virgo dwarfs, but a lower mean $S_N$ than Coma UDGs at fixed luminosity. Their GCs are predominantly blue, with a small contribution from red clusters in the more massive UDGs. The combined GC luminosity function is consistent with those observed in dwarf galaxies, showing no evidence of being anomalously luminous. The diversity in their morphologies and their GC properties suggests no single process has given rise to all objects within the UDG class. Based on the available evidence, we conclude that UDGs are simply those systems that occupy the extended tails of the galaxy size and surface brightness distributions.

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