Galactic cannibalism in the galaxy cluster c0337-2522 at z=0.59
Galactic cannibalism in the galaxy cluster c0337-2522 at z=0.59
复制标题
星系团 c0337-2522 z=0.59 处的银河同类相食现象
DOI：
--
复制
发表时间：
2003
期刊：
影响因子：
--
通讯作者：
P. Rosati
中科院分区：
文献类型：
--
作者：
C. Nipoti;C. Nipoti;M. Stiavelli;L. Ciotti;T. Treu;P. Rosati
根据银河同类相食模型，cD星系是通过大质量星系的合并和较小恒星系统的吸积而在星系团的中心形成的；然而，缺乏该过程初始阶段的观察实例。我们已经确定了 cD 星系形成早期阶段的一个强有力的候选者：X 射线星团 C0337-2522 核心中的一组五个椭圆星系，红移 z = 0.59。借助数值模拟（其中星系由 N 体系统表示），我们研究了它们在 z = 0 之前的动力学演化；团簇暗物质分布也被描述为N体系统。我们探索五个星系中的一些在 z = 0 之前合并的假设，对星团的结构和动力学特征做出合理的假设。然后，我们将并合残骸的性质与真实椭圆星系的属性进行比较（例如其与基本平面、Faber-Jackson 和 MBH-σ0 关系的一致性），特别是，我们检查残骸是否具有 cD 星系典型的表面亮度剖面。我们发现，所考虑的星系群中的多次合并事件将在 z = 0 之前发生，并且合并残余保留了基本平面和 Faber-Jackson 关系，而其相对于 MBH-σ0 关系的行为对黑洞合并的细节非常敏感。然而，我们模拟的最终产品更类似于“正常”的巨型椭圆星系，而不是具有特征性漫射光晕的 cD 星系，从而证实了之前的迹象，即 cD 星系的形成并不是星系团中心合并的必然结果。
According to the galactic cannibalism model, cD galaxies are formed in the centre of galaxy clusters by merging of massive galaxies and accretion of smaller stellar systems; however, observational examples of the initial phases of this process are lacking. We have identified a strong candidate for this early stage of cD galaxy formation: a group of five elliptical galaxies in the core of the X-ray cluster C0337-2522 at redshift z = 0.59. With the aid of numerical simulations, in which the galaxies are represented by N-body systems, we study their dynamical evolution up to z = 0; the cluster dark matter distribution is also described as an N-body system. We explore the hypothesis that some of the five galaxies will have merged before z = 0, making reasonable assumptions on the structural and dynamical characteristics of the cluster. We then compare the properties of the merger remnant with those of real ellipticals (such as its accordance with the fundamental plane, the Faber–Jackson and the MBH–σ0 relations) and, in particular, we check whether the remnant has the surface brightness profile typical of cD galaxies. We find that a multiple merging event in the considered group of galaxies will take place before z = 0 and that the merger remnant preserves the fundamental plane and the Faber–Jackson relations, while its behaviour with respect to the MBH–σ0 relation is quite sensitive to the details of black hole merging. However, the end-products of our simulations are more similar to a ‘normal’ giant elliptical than to a cD galaxy with its characteristic diffuse luminous halo, thus confirming previous indications that the formation of cD galaxies is not a necessary consequence of galaxy merging at the cluster centre.