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arXiv 1208.3523astro-ph.CO
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Atlas3D项目- XX。早型星系的质量-尺寸和质量-σ分布:球核分数驱动运动学,质光比,分子气体分数和恒星初始质量函数

The Atlas3D project - XX. Mass-size and mass-sigma distributions of early-type galaxies: bulge fraction drives kinematics, mass-to-light ratio, molecular gas fraction and stellar initial mass function

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, Raffaella Morganti, Thorsten Naab, Tom Oosterloo, Marc Sarzi, Nicholas Scott, Paolo Serra, Anne-Marie Weijmans, Lisa M. Young

摘要:

我们研究了薄质量面(MP)(M,sigma,Re)的(M,sigma)和(M,Re)投影,它描述了星系人口的分布。银河系性质在MP上的分布特征为:(i)一个由两个幂律组成的排斥区,在M 3e 10 Msun处有一个间断。这导致平均M-σ关系在小σ和大σ时分别与M σ ^[2.3]和M σ ^[4.7]发生断裂;(ii)质量为M 2 e11 Msun的星系将以具有盘和螺旋星系的扁平快旋星系为主的低质量星系群与以相当圆的慢旋星系为主的大质量星系群分开;(iii)低于该质量,ETG的性质分布趋于沿恒定σ线恒定;(iv)它与旋涡星系的分布形成平行序列;(v)在更低的质量下,快旋ETG和晚旋ETG的分布自然地分别扩展到矮ETG(Sph)和矮不规则星(Im)。我们通过动力学模型表明,西格玛跟踪凸起分数,这将推动观察到的趋势M/L,Hbeta,颜色,IMF和分子气体分数。我们解释这是由于两个主要效应的结合:(i)增加的凸起分数,增加西格玛,大大提高了星系的恒星形成淬火的可能性,(ii)干合并,增加星系质量沿着几乎恒定的西格玛线,同时保持人口不变。[删节]

英文摘要:

We study the (M,sigma) and (M,Re) projections of the thin Mass Plane (MP) (M,sigma,Re) which describes the distribution of the galaxy population. The distribution of galaxy properties on the MP is characterized by: (i) a zone of exclusion described by two power-laws joined by a break at M 3e10 Msun. This results in a break in the mean M-sigma relation with Msigma^2.3 and M sigma^4.7 at small and large sigma respectively; (ii) a mass M 2e11 Msun which separates a population dominated by flat fast rotator with disks and spiral galaxies at lower masses, from one dominated by quite round slow rotators at larger masses; (iii) below that mass the distribution of ETGs properties tends to be constant along lines of constant sigma; (iv) it forms a parallel sequence with the distribution of spiral galaxies; (v) at even lower masses, the distribution of fast rotator ETGs and late spirals naturally extends to that of dwarf ETGs (Sph) and dwarf irregulars (Im) respectively. We show via dynamical models that sigma traces the bulge fraction, which drives the observed trends in M/L, Hbeta, colour, IMF and molecular gas fraction. We interpret this as due to a combination of two main effects: (i) an increase of the bulge fraction which increases sigma and greatly enhances the likelihood for a galaxy to have its star formation quenched, and (ii) dry merging, increasing galaxy mass along lines of nearly constant sigma, while leaving the population unchanged. [Abriged]

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