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arXiv 1709.03585astro-ph.GA
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SAMI星系巡天:运动学选择星系的内在形状

The SAMI Galaxy Survey: the intrinsic shape of kinematically selected galaxies

C. Foster, J. van de Sande, F. D'Eugenio, L. Cortese, R. M. McDermid, J. Bland-Hawthorn, S. Brough, J. Bryant, S. M. Croom, M. Goodwin, I. S. Konstantopoulos, J… 展开作者

C. Foster, J. van de Sande, F. D'Eugenio, L. Cortese, R. M. McDermid, J. Bland-Hawthorn, S. Brough, J. Bryant, S. M. Croom, M. Goodwin, I. S. Konstantopoulos, J. Lawrence, A. R. Lopez-Sanchez, A. M. Medling, M. S. Owers, S. N. Richards, N. Scott, D. S. Taranu, C. Tonini, T. Zafar

摘要:

利用悉尼AAO多积分场(SAMI)星系巡天的恒星运动学图和辅助成像数据,推断了运动学选择的星系样本的内在形状。我们实现了一个有效的和优化的算法,以适应固有的形状的星系使用一个既定的方法,同时反演的表观椭圆率和运动失调的分布。该算法的输出与以前的研究相比,星系的内在形状的基础上单独成像和我们重新分析的ATLAS 3D数据。我们的结果表明,大多数星系是扁圆轴对称的。我们的经验表明,星系的内在形状变化的功能,其旋转支持的“自旋”参数代理Lambda_Re测量。特别地,低自旋系统具有更高的三轴性发生率,而高自旋系统本质上更平坦和轴对称。星系的内在形状与它们的形成和合并历史有关。具有高自旋值的Galerkin具有与耗散小合并一致的内在形状,而低自旋系统的内在形状与无耗散多合并组装历史一致。从内在形状推断出的组装历史范围与宇宙学模拟的预期大致一致。

英文摘要:

Using the stellar kinematic maps and ancillary imaging data from the Sydney AAO Multi Integral field (SAMI) Galaxy Survey, the intrinsic shape of kinematically-selected samples of galaxies is inferred. We implement an efficient and optimised algorithm to fit the intrinsic shape of galaxies using an established method to simultaneously invert the distributions of apparent ellipticities and kinematic misalignments. The algorithm output compares favourably with previous studies of the intrinsic shape of galaxies based on imaging alone and our re-analysis of the ATLAS3D data. Our results indicate that most galaxies are oblate axisymmetric. We show empirically that the intrinsic shape of galaxies varies as a function of their rotational support as measured by the "spin" parameter proxy Lambda_Re. In particular, low spin systems have a higher occurrence of triaxiality, while high spin systems are more intrinsically flattened and axisymmetric. The intrinsic shape of galaxies is linked to their formation and merger histories. Galaxies with high spin values have intrinsic shapes consistent with dissipational minor mergers, while the intrinsic shape of low-spin systems is consistent with dissipationless multi-merger assembly histories. This range in assembly histories inferred from intrinsic shapes is broadly consistent with expectations from cosmological simulations.

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