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arXiv 1202.3308astro-ph.COastro-ph.GAastro-ph.SR
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早型星系中恒星初始质量函数的系统变化

A systematic variation of the stellar initial mass function in early-type galaxies

Michele Cappellari, Richard M. McDermid, Katherine Alatalo, Leo Blitz, Maxime Bois, Frederic Bournaud, M. Bureau, Alison F. Crocker, Roger L. Davies, Timothy A.… 展开作者

Michele Cappellari, Richard M. McDermid, Katherine Alatalo, Leo Blitz, Maxime Bois, Frederic Bournaud, M. Bureau, Alison F. Crocker, Roger L. Davies, Timothy A. Davis, P. T. de Zeeuw, Pierre-Alain Duc, Eric Emsellem, Sadegh Khochfar, Davor Krajnovic, Harald Kuntschner, Pierre-Yves Lablanche, Raffaella Morganti, Thorsten Naab, Tom Oosterloo, Marc Sarzi, Nicholas Scott, Paolo Serra, Anne-Marie Weijmans, Lisa M. Young

摘要:

我们对星系的许多认识来自于分析其恒星发出的辐射。它依赖于描述星族形成时恒星质量分布的恒星初始质量函数(IMF)。因此,IMF的知识对星系演化的几乎每个方面都至关重要。在国际货币基金组织第一次确定之后的半个多世纪里,对于它是否在不同星系中具有普遍性,还没有达成共识。先前的研究表明,IMF和星系中心的暗物质部分不可能同时具有普适性,但它们不能打破这两种效应之间的简并性。直到最近才有迹象表明,大质量椭圆星系可能没有与我们银河系相同的IMF。在这里,我们报告明确的证据,一个强大的系统变化的IMF在早期型星系作为其恒星的质量与光的比例的函数,产生的差异高达三个因素的质量。这是推断出详细的动力学模型的二维恒星运动学的大型dmas3D代表样本附近的早期型星系跨越两个数量级的恒星质量。我们的发现表明,IMF密切依赖于星系的形成历史。

英文摘要:

Much of our knowledge of galaxies comes from analysing the radiation emitted by their stars. It depends on the stellar initial mass function (IMF) describing the distribution of stellar masses when the population formed. Consequently knowledge of the IMF is critical to virtually every aspect of galaxy evolution. More than half a century after the first IMF determination, no consensus has emerged on whether it is universal in different galaxies. Previous studies indicated that the IMF and the dark matter fraction in galaxy centres cannot be both universal, but they could not break the degeneracy between the two effects. Only recently indications were found that massive elliptical galaxies may not have the same IMF as our Milky Way. Here we report unambiguous evidence for a strong systematic variation of the IMF in early-type galaxies as a function of their stellar mass-to-light ratio, producing differences up to a factor of three in mass. This was inferred from detailed dynamical models of the two-dimensional stellar kinematics for the large Atlas3D representative sample of nearby early-type galaxies spanning two orders of magnitude in stellar mass. Our finding indicates that the IMF depends intimately on a galaxy's formation history.

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