AI 中文总结
研究利用射电连续谱观测约束拱星团的年龄、质量和初始质量函数等关键参数。通过比较观测与模拟星团的射电通量密度分布，采用多种恒星演化模型和金属丰度进行模拟，确定了星团参数范围及IMF斜率，为表征银河系中心新发现的年轻大质量星团提供了有用信息。
AI 中文摘要
位于银河系中心的拱星团是研究大质量恒星和年轻大质量星团性质的最佳天体物理实验室之一，但该星团的几个基本参数仍不确定。本文通过将拱星团观测到的恒星射电通量密度分布与一组合成星团的分布进行比较，来约束关键星团参数（星团年龄、质量和初始质量函数，IMF）。利用之前对拱星团的射电连续谱研究中的深X波段（10GHz）甚大阵列数据，用年龄、质量和IMF斜率三个参数对每个模拟星团进行建模，使用三种不同的恒星演化模型（GENEC、PARSEC和MIST）在两种不同金属丰度（太阳金属丰度$Z = 0.014$和超太阳金属丰度$Z = 0.020$）下进行马尔可夫链蒙特卡罗模拟以探索参数空间。所有模型和金属丰度给出的优选年龄在$2\lesssim t_{\rm age}/{\rm Myr}\lesssim 3$范围内，得到平均IMF斜率$\alpha_{\rm IMF}=-1.85^{+0.28}_{-0.20}$，不确定性主要由星团质量和IMF斜率的简并性主导。若以前期红外研究的IMF斜率为先验，星团质量分布峰值在$\sim2.7\times10^4\, M_\odot$，并能确定拱星团质量下限$\gtrsim2\times10^4 M_\odot$。射电连续谱观测可用于约束年轻大质量星团参数，对于拱星团，无需先光谱信息就能确定年龄，有助于表征银河系中心新发现的年轻大质量星团，结果支持银河系中心或一般年轻大质量星团中可能偏好顶部重的IMF这一观点。
英文摘要
The Arches cluster, located in the Galactic Centre (GC) is one of the best astrophysical laboratories to study the properties of massive stars and young massive clusters (YMCs). However, several fundamental parameters of the Arches cluster remain uncertain. Our goal is to constrain key cluster parameters (cluster age, mass, and initial mass function, IMF) by comparing the observed stellar radio flux density distribution of the Arches cluster to those derived from a set of synthetic clusters. We use the deep X-band (10 GHz) Very Large Array data from our previous radio continuum study of the Arches cluster. We model each simulated cluster with three parameters: age, mass, and IMF slope. We use three different stellar evolutionary models: GENEC, PARSEC, and MIST at two different metallicities, solar ($Z=0.014$) and super-solar ($Z=0.020$). We run Markov-chain Monte-Carlo simulations for each model/metallicity combination in order to explore parameter space. All models and metallicities return preferred ages in the $2\lesssim t_{\rm age}/{\rm Myr}\lesssim 3$ range. We obtain an IMF slope of $α_{\rm IMF}=-1.85^{+0.28}_{-0.20}$, averaged over all models, where uncertainties are dominated by the degeneracy between cluster mass and IMF slope. If we use the IMF slope from previous infrared studies as prior, the cluster mass distributions peak at $\sim2.7\times10^4\, M_\odot$ and we can establish a lower limit at $\gtrsim2\times10^4 M_\odot$ for the Arches cluster mass. Radio continuum observations of their most massive stars can be used to constrain YMC parameters. In the case of the Arches cluster, age can be determined regardless of prior spectroscopic information, which can be useful to characterise newly discovered YMCs in the GC. Our results support the idea that a top-heavy IMF may be preferred in the GC or in YMCs in general.
Comments14 pages. Accepted for publication in A&A
