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arXiv 1209.4357astro-ph.CO
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核与早型星系的运动

Cores and the Kinematics of Early-Type Galaxies

Tod R. Lauer

摘要:

我已经结合了Emsellem等人的ATLAS 3D旋转措施的大样本的早期型星系与基于HST的分类,其中心结构的特征与核心的星系的旋转速度。“核心星系”旋转缓慢,而“幂律星系”(没有核心的星系)旋转迅速,证实了Faber等人的分析。特别是Mv >-20的小核心星系的缓慢旋转,使它们与更大质量的核心星系一致。ATLAS 3D“快速旋转”和“慢速旋转”的早型星系本质上分别与幂律星系和核心星系相同,或者是基于旋转、等照度线形状和中心结构的两个椭圆星系家族。ATLAS 3D快速旋转星系确实包含了大约一半的核心星系,但它们的旋转振幅总是在该子集的下边界。基本上所有的核心星系都具有ATLAS 3D旋转振幅λ_(Re/2)<= 0.25,而所有λ_(Re/2)> 0.25和形状偏心率> 0.2的星系都没有核心。早期型星系的图形旋转和中心结构应该一起使用,以区分似乎是由“湿”和“干”合并形成的系统。

英文摘要:

I have combined the Emsellem et al. ATLAS3D rotation measures of a large sample of early-type galaxies with HST-based classifications of their central structure to characterize the rotation velocities of galaxies with cores. "Core galaxies" rotate slowly, while "power-law galaxies" (galaxies that lack cores) rotate rapidly, confirming the analysis of Faber et al. Significantly, the amplitude of rotation sharply discriminates between the two types in the -19 > Mv > -22 domain over which the two types coexist. The slow rotation in the small set of core galaxies with Mv > -20, in particular, brings them into concordance with the more massive core galaxies. The ATLAS3D "fast-rotating" and "slow-rotating" early-type galaxies are essentially the same as power-law and core galaxies, respectively, or the Kormendy & Bender two families of elliptical galaxies based on rotation, isophote shape, and central structure. The ATLAS3D fast rotators do include roughly half of the core galaxies, but their rotation-amplitudes are always at the lower boundary of that subset. Essentially all core galaxies have ATLAS3D rotation-amplitudes lambda_(R_e/2) <= 0.25, while all galaxies with lambda_(R_e/2) > 0.25 and figure eccentricity > 0.2 lack cores. Both figure rotation and the central structure of early-type galaxies should be used together to separate systems that appear to have formed from "wet" versus "dry" mergers.

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