IOP Publishing Ltd.;Philadelphia: The American Astronomical Society
摘要:
摘要： ABSTRACT We studied the ellipticity distributions of elliptical galaxies in different environments. From the ninth data release of the Sloan Digital Sky Survey, we selected galaxies with absolute -band magnitudes between −21 and −22. We used the volume number densities of galaxies as the criterion for selecting the environments of the galaxies. Our samples were divided into three groups with different volume number densities. The ellipticity distributions of the elliptical galaxies differed considerably in these three groups of different density regions. We deprojected the observed 2D ellipticity distributions into intrinsic 3D shape distributions, and the result showed that the shapes of the elliptical galaxies were relatively spherically symmetric in the high density region (HDR) and that relatively more flat galaxies were present in the low density region (LDR). This suggests that the ellipticals in the HDRs and LDRs have different origins or that different mechanisms might be involved. The elliptical galaxies in the LDR are likely to have evolved from mergers in relatively anisotropic structures, such as filaments and webs, and might contain information on the anisotropic spatial distribution of their parent mergers. By contrast, elliptical galaxies in the HDR might be formed in more isotropic structures, such as galaxy clusters, or they might encounter more torqueing effects compared with galaxies in LDRs, thereby becoming rounder. 其他題名： APJ 其他題名： Astrophys. J 出版者： Philadelphia: The American Astronomical Society 出版日期： 2016-10-20 出處： The Astrophysical journal, 2016-10, Vol.830 (2), p.123 資源來源： Institute of Physics Journals 版權： 2016. The American Astronomical Society. All rights reserved. 版權： Copyright IOP Publishing Oct 20, 2016 識別號： ISSN: 0004-637X 識別號： ISSN: 1538-4357 識別號： EISSN: 1538-4357 識別號： DOI: 10.3847/0004-637X/830/2/123
