用深HST/ACS测光研究长蛇座I透镜星系中的球状星团
A study of globular clusters in a lenticular galaxy in Hydra I from deep HST/ACS photometry
摘要：
利用HST/ACS在F475 W（$g_{F475W}$）和F606 W（$V_{F606W}$）波段的精细深度光学成像数据，研究了Hydra I星系团中中等质量透镜状星系PGC 087327中球状星团（GC）种群的性质。我们检查光度（大小和颜色）和形态（紧凑性，伸长率等）。位于以PGC 087327为中心的$\sim19\times19$ kpc区域内的源的性质，并将它们与同一HST/ACS镶嵌图上的四个相邻场进行比较。这使我们能够确定GC候选名单，并使用背景去污方法检查其属性。相对于四个比较视野，PGC 087327显示GC $N_{GC}=82\pm9$的稳健过密度。在星系的估计星等上，这个数字意味着$S_N=1.8\pm0.7$的特定频率。尽管$g_{F475W}$和$V_{F606W}$通带的波长间隔很短，但颜色分布显示出明显的双峰性，在$\langle g_{F475W}{-}V_{F606W} \rangle =0.47\pm0.05$ mag处有一个蓝色峰，在$\langle g_{F475W}{-}V_{F606W}\rangle =0.62\pm0.03$ mag处有一个红色峰。我们还观察到红色GC相对于蓝色GC的径向分布的典型陡峭斜率。由于可用数据的独特深度，我们表征的GC光度函数（GCLF）远远超出预期的GCLF周转。我们发现$g^{TOM}_{F475W} = 26.54\pm0.10$ mag和$V^{TOM}_{F606W} = 26.08 \pm 0.09$ mag，它们在校准后产生$D_{GCLF} = 56.7 \pm 4.3(statistical) \pm 5.2(systematic)$ Mpc的距离。
英文摘要：
We take advantage of exquisitely deep optical imaging data from HST/ACS in the F475W ($g_{F475W}$) and F606W ($V_{F606W}$) bands, to study the properties of the globular cluster (GC) population in the intermediate mass lenticular galaxy PGC 087327, in the Hydra I galaxy cluster. We inspect the photometric (magnitudes and color) and morphometric (compactness, elongation, etc.) properties of sources lying in an area of $\sim19\times19$ kpc centered on PGC 087327, and compare them with four neighbouring fields over the same HST/ACS mosaic. This allowed us to identify a list of GC candidates and to inspect their properties using a background decontamination method. Relative to the four comparison fields, PGC 087327 shows a robust overdensity of GCs, $N_{GC}=82\pm9$. At the estimated magnitude of the galaxy, this number implies a specific frequency of $S_N=1.8\pm0.7$. In spite of the short wavelength interval available with the $g_{F475W}$ and $V_{F606W}$ passbands, the color distribution shows a clear bimodality with a blue peak at $\langle g_{F475W}{-}V_{F606W} \rangle =0.47\pm0.05$ mag and a red peak at $\langle g_{F475W}{-}V_{F606W}\rangle =0.62\pm0.03$ mag. We also observe the typical steeper slope of the radial distribution of red GCs relative to blue ones. Thanks to the unique depth of the available data, we characterize the GC luminosity function (GCLF) well beyond the expected GCLF turn-over. We find $g^{TOM}_{F475W} = 26.54\pm0.10$ mag and $V^{TOM}_{F606W} = 26.08 \pm 0.09$ mag, which after calibration yields a distance of $D_{GCLF} = 56.7 \pm 4.3(statistical) \pm 5.2(systematic)$ Mpc.
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。
