http://arxiv.org/abs/1802.10105

The alignment between satellites and central galaxies has been studied in detail in both in observational and theoretical works. The widely accepted fact is that the satellites preferentially reside along the major axis of their central galaxy. However, the origin and large scale environment dependence of this alignment are still unknown. In an attempt to figure out those, we use data constructed from SDSS DR7 to investigate the large scale environmental dependence of this alignment with emphasis on examining the alignments’ dependence on the color of the central galaxy. We find a very strong large scale environmental dependence of the satellite-central alignment in groups that are dominated by blue centrals. Satellites of blue central galaxies that reside in knots are preferentially located perpendicular to the major axis of the central galaxy, and the alignment angle decreases with environment namely when going from knots to voids. The alignment angle strongly depend on the ${}^{0.1}(g-r)$ colour of central galaxies. We suggest that the satellite-central alignment is the result of a competition between satellite accretion within large scale structure on the one hand, and galaxy evolution inside host haloes on the other. For groups containing red central galaxies, the satellite-central alignment is mainly determined by the evolution effect, while for blue central dominated groups, the effect of large scale structure plays a more important role, especially in knot environments. Our results provide an explanation for how the satellite-central alignment forms within different large scale environments. The perpendicular case that we see in groups and knots with blue central galaxies may also provide insight into understanding similar polar arrangements such the formation of the Milky Way and Centaurus A’s satellite system.

Read this paper on arXiv…

P. Wang, Y. Luo, X. Kang, et. al.
Thu, 1 Mar 18
2/66

Comments: 10 pages, 5 figures and 2 tables, submitted to ApJ, comments welcome