Near-infrared observations of galaxies in Pisces-Perseus V. On the origin of bulges
Near-infrared observations of galaxies in Pisces-Perseus V. On the origin of bulges
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双鱼座-英仙座星系的近红外观测 V. 核球的起源
DOI：
10.1051/0004-6361:20031679
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发表时间：
2003
影响因子：
6.5
通讯作者：
C. Giovanardi
中科院分区：
文献类型：
--
作者：
L. Hunt;D. Pierini;C. Giovanardi
我们研究了 108 个盘状星系样本的核球和盘状结构参数的标度关系。各个星系的结构参数是通过对其 H 波段表面亮度分布 �� 进行二维核球/盘分解而获得的。凸起使用具有可变整数形状索引 n 的广义指数 (Sersic) 进行建模。我们发现，凸块有效尺度长度 r B e 和光度 MB 随着 n 的增加而增加，但圆盘特性与凸块形状无关。随着哈勃类型 T 的增加，凸起的发光度变得越来越低，其平均有效表面亮度也变得越来越暗；盘面显示出类似但弱得多的趋势。当凸起参数 ( , r B , MB ) 与圆盘参数 ( , r D , M D ) 进行比较时，它们对于 n = 1 凸起紧密相关。随着 n 的增加，相关性逐渐恶化，使得 n = 4 的凸起看起来几乎独立于它们的圆盘。 Kormendy 关系与 r Be 的关系显示取决于凸出形状 n；这两个参数在 n = 4 个凸起 (r = 0.8) 中紧密相关，并且随着 n 的减小而逐渐减弱； disk 和 r D e 密切相关 (r = 0.7)。凸块与圆盘尺寸之比 r B e /r D e 与哈勃类型无关，但对于指数凸块而言较小； n = 1 个凸起的平均值 r B /r D 比 n = 4 的平均值小 4 倍，且分布小 9 倍。具有指数核球的强棒状SB星系比无棒状星系更亮。指数凸起似乎与其底层圆盘密切相关，而 n 值较高的凸起则不太如此； n = 4 个凸起和它们的圆盘显然没有关系。我们将我们的结果解释为与长期进化场景最一致，其中圆盘中的耗散过程负责在大多数螺旋中形成凸起。
We investigate the scaling relations of bulge and disk structural parameters for a sample of 108 disk galaxies. Structural parameters of individual galaxies are obtained from two-dimensional bulge/disk decomposition of their H-band sur- face brightness distributions �� . Bulges are modelled with a generalized exponential (Sersic) with variable integer shape index n. We find that bulge effective scalelengths r B e and luminosity M B increase with increasing n, but disk properties are independent of bulge shape. As Hubble type T increases, bulges become less luminous and their mean effective surface brightness gets fainter; disk shows a similar, but much weaker, trend. When bulge parameters ( , r B , M B ) are compared with disk ones ( , r D , M D ), they are tightly correlated for n = 1 bulges. The correlations gradually worsen with increasing n such that n = 4 bulges appear virtually independent of their disks. The Kormendy relation, vs. r B e , is shown to depend on bulge shape n; the two parameters are tightly correlated in n = 4 bulges (r = 0.8), and increasingly less so as n decreases; disk and r D e are well correlated (r = 0.7). Bulge-to-disk size ratios r B e /r D e are independent of Hubble type, but smaller for exponential bulges; the mean r B /r D for n = 1 bulges is 4 times smaller than that for n = 4, with a spread which is 9 times smaller. Strongly barred SB galaxies with exponential bulges are more luminous than their unbarred counterparts. Exponential bulges appear to be closely related to their underlying disks, while bulges with higher n values are less so; n = 4 bulges and their disks apparently have no relation. We interpret our results as being most consistent with a secular evolutionary scenario, in which dissipative processes in the disk are responsible for building up the bulges in most spirals.