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arXiv 0906.4628astro-ph.CO
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星系演化的另一种方法

A Different Approach to Galaxy Evolution

Alvio Renzini

摘要:

研究了恒星形成星系的恒星形成率(SFR)与恒星质量(M)和宇宙时间(t)的关系,即SFR与M × t^{-2.5}成正比。结果表明,小的系统差异SFR显着放大的过程中的时间:星系与平均以上的SFR运行到准指数质量和SFR增长,而低于平均SFR的星系避免这种指数增长和发展与适度的质量增加。有观点认为,遵循第一条路径的星系如果一直形成恒星到现在,将大大过度生长,因此应该熄灭恒星形成并变得被动。出于同样的原因,那些避免了准指数增长的恒星可能会一直形成到现在。因此,它被证实,这种发散行为可以帮助理解的起源之间的二分法被动,球状星系,恒星形成,盘星系。

英文摘要:

The consequences are explored of an observationally established relation of the star formation rate (SFR) of star-forming galaxies with their stellar mass (M) and cosmic time (t), such that SFR is proportional to M x t^{-2.5}. It is shown, that small systematic differences in SFR dramatically amplify in the course of time: galaxies with above average SFR run into quasi-exponential mass and SFR growth, while galaxies with below average SFR avoid such exponential growth and evolve with moderate mass increase. It is argued that galaxies following the first path would enormously overgrow if keeping to form stars all the way to the present, hence should quench star formation and turn passive. By the same token, those instead avoiding the quasi-exponential growth may keep to form stars up to the present. Thus, it is conjectured that this divergent behaviour can help understanding the origin of the dichotomy between passive, spheroidal galaxies, and star-forming, disk galaxies.

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