arXiv 2010.059302020-10astro-ph.GA

从不寻常的球状星团人口限制NGC1052-DF2的形成

Constraining the formation of NGC1052-DF2 from its unusual globular cluster population

Sebastian Trujillo-Gomez, J. M. Diederik Kruijssen, Benjamin W. Keller, Marta Reina-Campos

备注：: 14 pages, 6 figures; Accepted for publication in MNRAS (June 17, 2021)
DOI：: 10.1093/mnras/stab1895

摘要：

超漫射星系NGC 1052-DF 2的暗物质含量很低，并且拥有一个非常不寻常的球状星团（GC），它的中位光度是大多数星系的$\sim4$倍，包含了大约5%的星系恒星。我们应用一个理论模型，预测作为银河系环境的函数的初始集群质量函数调查DF 2的奇特GC系统的起源。利用GC质量函数，该模型约束了星系GC形成时的恒星形成条件，即$\sim9~\rm{Gyr}$之前。我们预测，GC形成的环境中具有非常高的气体表面密度，$Σ_{\rm ISM} \gtrsim 10^3 M_{\odot} \rm{pc}^{-2}$，和强大的离心力的支持，$Ω\gtrsim 0.7~\rm{Myr}^{-1}$，类似于附近的环核恒星爆发和银河系的中心区域。这些极端的条件需要形成观察到的GC人口意味着一个非常高的团簇形成效率的$\gtrsim 78$ %，并与目前的星系的弥漫性形成强烈的对比。由于核星爆会导致GC的快速螺旋，并且由于没有核星团而被排除，我们认为GC可能是在$z\sim1.3$的一次主要合并过程中形成的。合并后的残余物一定经历了恒星（或许还有暗物质）成分的显著膨胀，才达到目前的低表面亮度，这导致了一个有趣的可能性，即DF 2的极端GC人口的形成导致了它成为UDG。如果这是真的，那么这种强有力的结构演变将对理解UDG的起源产生重要影响。

英文摘要：

The ultra-diffuse galaxy (UDG) NGC1052-DF2 has a low dark matter content and hosts a very unusual globular cluster (GC) population, with a median luminosity $\sim4$ times higher than in most galaxies and containing about 5~per~cent of the galaxy's stars. We apply a theoretical model that predicts the initial cluster mass function as a function of the galactic environment to investigate the origin of DF2's peculiar GC system. Using the GC mass function, the model constrains the star-forming conditions in the galaxy during the formation of its GCs, $\sim9~\rm{Gyr}$ ago. We predict that the GCs formed in an environment with very high gas surface density, $Σ_{\rm ISM} \gtrsim 10^3 M_{\odot} \rm{pc}^{-2}$, and strong centrifugal support, $Ω\gtrsim 0.7~\rm{Myr}^{-1}$, similar to nearby circum-nuclear starbursts and the central region of the Milky Way. These extreme conditions required to form the observed GC population imply a very high cluster formation efficiency of $\gtrsim 78$ per cent, and contrast strongly with the current diffuse nature of the galaxy. Since a nuclear starburst would lead to the rapid in-spiral of the GCs and is ruled out by the absence of a nuclear star cluster, we propose that the GCs plausibly formed during a major merger at $z\sim1.3$. The merger remnant must have undergone significant expansion of its stellar (and perhaps also its dark matter) component to reach its low present surface brightness, leading to the interesting possibility that it was the formation of DF2's extreme GC population that caused it to become a UDG. If true, this strong structural evolution would have important implications for understanding the origins of UDGs.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

摘要：

英文摘要：

相关论文