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arXiv 0905.0469astro-ph.CO
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早型星系中的球状星团与恒星晕的联系

The globular clusters-stellar haloes connection in early type galaxies

Juan C. Forte, E. Irene Vega, Favio R. Faifer

摘要:

本文探讨了早期型星系的恒星星族是否以及在多大程度上可以通过其球状星团系统的颜色分布来追踪。基于室女座ACS数据的星系样本的分析,是先前在巨型椭圆星系NGC 1399和NGC 4486的情况下取得成功的方法的扩展,并假设两个占主导地位的GC种群沿着扩散的恒星星族形成,共享集群化学丰度和空间分布。结果表明:(a)综合星系颜色可以在光度不确定度范围内匹配,并且与一个狭窄的年龄范围相一致;(b)推断的质量光度比和恒星质量在文献中可获得的数值范围内; c)大多数球状星团系统在由团簇形成效率定义的体积空间中占据厚平面,恒星总质量和投影表面质量密度。红色星团的形成效率参数显示出与投影恒星质量密度的依赖关系,而蓝色球状星团则没有。反过来,最亮的星系似乎明显脱离该平面,作为过去主要合并的可能结果; d)恒星质量-金属丰度关系相对较浅,但在$M_*\approx 10^{10} M_\odot$处显示出斜率变化。恒星质量较小的星系团主要表现为单峰球状星团颜色分布。这一结果可能表明,质量较小的星系无法保留化学富集的星际物质。

英文摘要:

This paper explores if, and to what an extent, the stellar populations of early type galaxies can be traced through the colour distribution of their globular cluster systems. The analysis, based on a galaxy sample from the Virgo ACS data, is an extension of a previous approach that has been successful in the cases of the giant ellipticals NGC 1399 and NGC 4486, and assumes that the two dominant GC populations form along diffuse stellar populations sharing the cluster chemical abundances and spatial distributions. The results show that a) Integrated galaxy colours can be matched to within the photometric uncertainties and are consistent with a narrow range of ages; b) The inferred mass to luminosity ratios and stellar masses are within the range of values available in the literature; c) Most globular cluster systems occupy a thick plane in the volume space defined by the cluster formation efficiency, total stellar mass and projected surface mass density. The formation efficiency parameter of the red clusters shows a dependency with projected stellar mass density that is absent for the blue globulars. In turn, the brightest galaxies appear clearly detached from that plane as a possible consequence of major past mergers; d) The stellar mass-metallicity relation is relatively shallow but shows a slope change at $M_*\approx 10^{10} M_\odot$. Galaxies with smaller stellar masses show predominantly unimodal globular cluster colour distributions. This result may indicate that less massive galaxies are not able to retain chemically enriched intestellar matter.

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。

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