THE STRUCTURE OF CLASSICAL BULGES AND PSEUDOBULGES: THE LINK BETWEEN PSEUDOBULGES AND SÉRSIC INDEX
THE STRUCTURE OF CLASSICAL BULGES AND PSEUDOBULGES: THE LINK BETWEEN PSEUDOBULGES AND SÉRSIC INDEX
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DOI：
10.1088/0004-6256/136/2/773
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发表时间：
2008-05
期刊：
影响因子：
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通讯作者：
D. Fisher;N. Drory
中科院分区：
文献类型：
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作者：
D. Fisher;N. Drory
在本文中，我们研究的性质的pseudobulges（出现类似盘星系的凸起）和经典的bulges（出现类似的E-型星系的凸起）在bulge-disk分解。我们发现，凸起的Sérsic指数，nb的分布是双峰的，这种双峰与形态的凸起。伪凸起具有nb 2，而经典凸起具有nb 2，几乎没有重叠。此外，伪星系核并不像经典星系核和椭圆星系那样遵循Sérsic指数与结构参数或基本平面的光度投影的相关性。我们发现，pseudobulges系统比经典的凸起平坦，因此在它们的形态和形状更像盘。我们没有发现显着差异不同的隆起形态，我们统称为pseudobulges（核螺旋，核环，核酒吧，核补丁），他们似乎表现出类似的所有参数的相关性。在Sérsic指数、扁平化和膨胀与总膨胀比中，区别似乎是在经典膨胀和伪膨胀之间，而不是在不同的伪膨胀形态之间。与经典隆起相反，伪隆起的Sérsic指数与B/T无关。此外，伪隆起的半光半径与盘的尺度长度相关;这不是经典隆起的情况。Sérsic指数和鳞片长度与隆起形态的相关性表明，长期进化正在创造具有低Sérsic指数的假隆起，而其他过程（例如，主要合并）负责在经典的凸起和椭圆星系的较高的Sérsic指数。
In this paper, we study the properties of pseudobulges (bulges that appear similar to disk galaxies) and classical bulges (bulges which appear similar to E-type galaxies) in bulge-disk decompositions. We show that the distribution of bulge Sérsic indices, nb, is bimodal, and this bimodality correlates with the morphology of the bulge. Pseudobulges have nb ≲ 2 and classical bulges have nb ≳ 2 with little to no overlap. Also, pseudobulges do not follow the correlations of Sérsic index with structural parameters or the photometric projections of the fundamental plane in the same way that classical bulges and elliptical galaxies do. We find that pseudobulges are systematically flatter than classical bulges and thus more disk-like in both their morphology and shape. We do not find significant differences between different bulge morphologies which we are collectively calling pseudobulges (nuclear spirals, nuclear rings, nuclear bars, and nuclear patchiness); they appear to behave similarly in all parameter correlations. In the Sérsic index, flattening, and bulge-to-total ratio, the distinction appears to be between classical bulges and pseudobulges, not between different pseudobulge morphologies. The Sérsic index of the pseudobulges does not correlate with B/T, in contrast to classical bulges. Also, the half-light radius of the pseudobulge correlates with the scale length of the disk; this is not the case for classical bulges. The correlation of Sérsic index and scale lengths with bulge morphology suggests that secular evolution is creating pseudobulges with low-Sérsic index and that other processes (e.g., major mergers) are responsible for the higher Sérsic index in classical bulges and elliptical galaxies.