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arXiv 1003.4747astro-ph.CO
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质量和环境作为SDSS和zCOSMOS星系演化的驱动力以及Schechter函数的起源

Mass and environment as drivers of galaxy evolution in SDSS and zCOSMOS and the origin of the Schechter function

Y. Peng, S. J. Lilly, K. Kovac, M. Bolzonella, L. Pozzetti, A. Renzini, G. Zamorani, O. Ilbert, C. Knobel, A. Iovino, C. Maier, O. Cucciati, L. Tasca, C. M. Car… 展开作者

Y. Peng, S. J. Lilly, K. Kovac, M. Bolzonella, L. Pozzetti, A. Renzini, G. Zamorani, O. Ilbert, C. Knobel, A. Iovino, C. Maier, O. Cucciati, L. Tasca, C. M. Carollo, J. Silverman, P. Kampczyk, L. de Ravel, D. Sanders, N. Scoville, T. Contini, V. Mainieri, M. Scodeggio, J. -P. Kneib, O. Le Fevre, S. Bardelli, A. Bongiorno, K. Caputi, G. Coppa, S. de la Torre, P. Franzetti, B. Garilli, F. Lamareille, J. -F. Le Borgne, V. Le Brun, M. Mignoli, E. Perez Montero, R. Pello, E. Ricciardelli, M. Tanaka, L. Tresse, D. Vergani, N. Welikala, E. Zucca, P. Oesch, U. Abbas, L. Barnes, R. Bordoloi, D. Bottini, A. Cappi, P. Cassata, A. Cimatti, M. Fumana, G. Hasinger, A. M. Koekemoer, A. Leauthaud, D. Maccagni, C. Marinoni, H. J. McCracken, P. Memeo, B. Meneux, P. Nair, C. Porciani, V. Presotto, R. Scaramella

摘要:

我们探讨了SDSS,zCOSMOS和其他调查中的质量,恒星形成率和环境之间的相互关系。质量和环境的差异效应在z ~ 1上是完全可分离的,这表明两个不同的过程在起作用,“质量猝灭”和“环境猝灭”。在固定的过密度下,环境淬灭显然不会随着历元的变化而变化到z ~ 1,这表明它发生在宇宙中大尺度结构的发展过程中。恒星形成星系的质量函数形状的观测恒定性,要求M* 周围和以上星系的质量猝灭必须与它们在z < 2时的恒星形成速率成正比。我们假设,这个简单的质量猝灭定律也适用于更广泛的恒星质量和时代的范围。这两个简单的猝灭过程,加上一些由于合并而产生的额外猝灭,然后自然产生(a)恒星形成星系的准静态Schechter质量函数,其值M* 由恒星形成和质量猝灭速率之间的比例确定,(b)被动星系的双Schechter函数有两个分量:占主导地位的一个是由质量淬灭产生的,与恒星形成星系具有完全相同的M*,但α值较浅+1,而另一个是由环境效应产生的,与恒星形成星系具有相同的M* 和α值,并且在高密度环境中更大。随后淬灭星系的合并在密度更大的环境中稍微修改了这些预测,稍微增加了M*,使α更负。所有这些详细的Schechter参数之间的定量关系确实可以在SDSS中看到,为我们简单的基于几何的模型提供了强有力的支持。该模型自然产生的被动星系的“反层次”运行的平均年龄和α元素丰度与质量。

英文摘要:

We explore the inter-relationships between mass, star-formation rate and environment in the SDSS, zCOSMOS and other surveys. The differential effects of mass and environment are completely separable to z ~ 1, indicating that two distinct processes are operating, "mass-quenching" and "environment-quenching". Environment-quenching, at fixed over-density, evidently does not change with epoch to z ~ 1, suggesting that it occurs as large-scale structure develops in the Universe. The observed constancy of the mass-function shape for star-forming galaxies, demands that the mass-quenching of galaxies around and above M*, must be proportional to their star-formation rates at all z < 2. We postulate that this simple mass-quenching law also holds over a much broader range of stellar mass and epoch. These two simple quenching processes, plus some additional quenching due to merging, then naturally produce (a) a quasi-static Schechter mass function for star-forming galaxies with a value of M* that is set by the proportionality between the star-formation and mass-quenching rates, (b) a double Schechter function for passive galaxies with two components: the dominant one is produced by mass-quenching and has exactly the same M* as the star-forming galaxies but an alpha shallower by +1, while the other is produced by environment effects and has the same M* and alpha as the star-forming galaxies, and is larger in high density environments. Subsequent merging of quenched galaxies modifies these predictions somewhat in the denser environments, slightly increasing M* and making alpha more negative. All of these detailed quantitative relationships between the Schechter parameters are indeed seen in the SDSS, lending strong support to our simple empirically-based model. The model naturally produces for passive galaxies the "anti-hierarchical" run of mean ages and alpha-element abundances with mass.

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