arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1102.5099astro-ph.CO
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获胜者是:星系质量

And the winner is: galaxy mass

Daniel Thomas

摘要:

已知环境会影响星系的形成和演化,通过众所周知的形态-密度关系可以最好地观察到。我们研究了环境对早型星系演化的影响,选取了3,360个星系作为观测样本,在红移0.05<z<0.06的范围内进行观测,分析了光度加权年龄、金属丰度和α/Fe比作为环境和星系质量的函数。我们发现,平均有10%的早期类型星系通过较小的最近恒星形成而恢复活力。这一比例随着星系质量和环境密度的降低而增加。然而,大部分的人口服从一个定义良好的年龄,金属丰度,α/Fe比与星系质量是独立的环境标度。我们的研究结果有助于在最近的文献中越来越多的证据表明,星系质量是星系形成的主要驱动力。甚至形态密度关系实际上可能是质量驱动的,作为环境依赖的特征星系质量加上晚型星系形态在低质量星系中更普遍的事实的结果。

英文摘要:

The environment is known to affect the formation and evolution of galaxies considerably best visible through the well-known morphology-density relationship. We study the effect of environment on the evolution of early-type galaxies for a sample of 3,360 galaxies morphologically selected by visual inspection from the SDSS in the redshift range 0.05<z<0.06, and analyse luminosity-weighted age, metallicity, and alpha/Fe ratio as function of environment and galaxy mass. We find that on average 10 per cent of early-type galaxies are rejuvenated through minor recent star formation. This fraction increases with both decreasing galaxy mass and decreasing environmental density. However, the bulk of the population obeys a well-defined scaling of age, metallicity, and alpha/Fe ratio with galaxy mass that is independent of environment. Our results contribute to the growing evidence in the recent literature that galaxy mass is the major driver of galaxy formation. Even the morphology-density relationship may actually be mass-driven, as the consequence of an environment dependent characteristic galaxy mass coupled with the fact that late-type galaxy morphologies are more prevalent in low-mass galaxies.

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