论文标题
由于z = 0.1
Growth of disc-like pseudo-bulges in SDSS DR7 since z = 0.1
论文作者
论文摘要
宇宙学模拟预测的是比当地宇宙中的观察性凸起更多的古典凸起。在这里，我们使用来自SDSS DR7的近39,000个未挂牌的圆盘星系的光度参数来量化凸起的演变，这些参数由两个组件很好地表示。我们采用了Sérsic指数和Kormendy关系，与单独的经典凸起和类似圆盘的伪柱结合在一起。我们发现，随着宇宙年龄的增长，伪柱（经典凸起）的比例会平稳增加（减小）。在宇宙的历史中，当经典的凸起和伪荷尔量相等时，就会出现一个点（$ z \约0.016 $）。伪荷尔的一部分随着圆盘半径半径比率增加，直到r $ _ {\ rm e} $/r $ _ {\ rm hlr} \约0.6 $表明浓缩盘是Pseudo-Bulge形成的最有利的位置。伪柱的平均椭圆度始终大于经典凸起的平均椭圆度，并且随着红移的降低而降低，表明凸起随着进化而更具轴对称性。同样，巨大的凸起正在以比低质量凸起更陡峭的速率朝轴对称。凸起的指数演变与银河系的其他光度特性没有紧密相关。使用$ s^4g $数据和$ n- $身体星系模型的多组分拟合样本，我们已经验证了我们的结果是一致的，甚至更为明显，具有多组分拟合和高分辨率光度法。
Cosmological simulations predict more classical bulges than their observational counterpart in the local Universe. Here, we quantify evolution of the bulges since $z=0.1$ using photometric parameters of nearly 39,000 unbarred disc galaxies from SDSS DR7 which are well represented by two components. We adopted a combination of the Sérsic index and Kormendy relation to separate classical bulges and disc-like pseudo-bulges. We found that the fraction of pseudo-bulges (classical bulges) smoothly increases (decreases) as the Universe gets older. In the history of the Universe, there comes a point ($z \approx 0.016$) when classical bulges and pseudo-bulges become equal in number. The fraction of pseudo-bulges rises with increasing bulge to disc half-light radius ratio until R$_{\rm e}$/R$_{\rm hlr} \approx 0.6$ suggesting concentrated disc is the most favourable place for pseudo-bulge formation. The mean ellipticity of pseudo-bulges is always greater than that of classical bulges and it decreases with decreasing redshift indicating that the bulges tend to be more axisymmetric with evolution. Also, the massive bulges are progressing towards axisymmetry at steeper rate than the low-mass bulges. There is no tight correlation of bulge Sérsic index evolution with other photometric properties of the galaxy. Using the sample of multi-component fitting of $S^4G$ data and $N-$body galaxy models, we have verified that our results are consistent or even more pronounced with multi-component fitting and high-resolution photometry.
