The intrinsic equatorial ellipticity of bulges
The intrinsic equatorial ellipticity of bulges
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凸起的固有赤道椭圆度
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
E. Simonneau
中科院分区：
文献类型：
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作者：
J. Méndez;J. Aguerri;E. Corsini;E. Simonneau
摘要 传统上，对星系结构参数的研究被用来了解核球的形成过程。然而，这项研究中丢失的一个部分是凸起的三维形状。在这项工作中，推导了148个无棒S0-Sb星系的星等限制样本的结构参数，以研究核球和盘参数之间的相关性以及核球固有赤道椭圆率的概率分布函数（PDF）。使用新算法 (GASP-2D) 对从 2MASS 巡天档案中提取的 J 波段星系图像进行二维核球盘分解。固有椭圆率的 PDF 源自观察到的凸起的椭圆率以及凸起与圆盘之间的错位的分布。 S0-Sb 星系中大约 80% 的核球不是扁球体，而是三轴椭球体。它们在赤道面内的平均轴比为<B/A>=0.85。它们的 PDF 对形态、光浓度和发光度没有显着依赖性。凸出物由合并组装而成和/或通过盘长期演化而长期生长的场景必须根据凸出物固有椭圆率的导出 PDF 进行测试。
Abstract Traditionally, the study of the structural parameters of galaxies have been used to understand the bulge formation processes. However, one piece lost in this study is the three-dimensional shape of the bulges. In this work, the structural parameters of a magnitude-limited sample of 148 unbarred S0-Sb galaxies were derived to study the correlations between bulge and disk parameters as well as the probability distribution function (PDF) of the intrinsic equatorial ellipticity of bulges. A new algorithm (GASP-2D) was used to perform the bidimensional bulge-disk decomposition of J-band galaxy images extracted from the archive of the 2MASS survey. The PDF of intrinsic ellipticities was derived from the distribution of the observed ellipticities of bulges and misalignments between bulges and disks. About 80% of bulges in S0-Sb galaxies are not oblate but triaxial ellipsoids. Their mean axial ratio in the equatorial plane is 〈B/A〉=0.85. There is not significant dependence of their PDF on morphology, light concentration, and luminosity. The scenarios in which bulges assembled from mergers and/or grew over long times through disk secular evolution have to be tested against the derived PDF of bulge intrinsic ellipticities.