On the Alignment of Galaxies in Clusters
- PDF / 699,077 Bytes
- 12 Pages / 594 x 792 pts Page_size
- 19 Downloads / 232 Views
ON THE ALIGNMENT OF GALAXIES IN CLUSTERS
H. M. Tovmassian1 and J. P. Torres-Papaqui2
We explore the distribution of position angles (PA) of galaxies in clusters. We selected for study the isolated clusters, since the distribution of the galaxy orientation in clusters with close neighbors could be altered by the gravitational influence of the latter. We assume that galaxies are aligned, if their number at one 90o position angle interval is more than twice higher than at the other 90o interval. We study the galaxy PA distribution at the outer regions of clusters with smaller space density, where the probability of the PA variation in the result of interactions between galaxies is smaller than at the dense central regions. We found that the alignment of galaxies is more often observed in poor clusters and concluded that originally galaxies were aligned, but in the result of accretion in time of field galaxies with arbitrary orientations and also due to the mutual interactions the relative number of aligned galaxies decreases. Keywords: galaxies: clusters - galaxies: alignment - galaxies: large-sale structure
1. Introduction
According to pancake scenario [1-3] galaxies form in the result of the gas-dust cloud collapse. At such case the position angles (PA) of galaxies will naturally be aligned independent on the cluster mass. According to Miller & Smith [4], Salvador-Sole & Solanes [5] Usami & Fujimoto [6], the galaxies could be aligned also at the hierarchical
1 2
377, W. California 30, Glendale, CA, USA, e-mail: [email protected] Departamento de Astronomía, Universidad de Guanajuato Apartado Postal 144, 36000, Guanajuato, Mexico
Published in Astrofizika, Vol. 63, No. 4, pp. 509-520 (March 2014). Original article submitted August 16, 2020. 0571-7256/19/6304-0447 ©2020 Springer Science+Business Media, LLC
447
scenario of the cluster origin due to the cluster tidal field. At the latter scenario the galaxies will be aligned predominantly in rich clusters. Thus the alignment of galaxies in clusters is a clue for the explanation of their origin. Therefore a lot of efforts have been undertaken in the past for study the distribution of the PA of galaxies in clusters. Some evidence on the alignment of galaxies with the parent cluster were reported by Sastry [7], Adams, Strom & Strom [8], Carter & Metcalfe [9], Binggeli [10], Struble & Peebles [11], Rhee & Katgert [12], Lambas et al. [13], Flin & Olowin [14], Fong, Stevenson & Shanks [15]. More certainly the alignment was found between orientations of the cluster and of the BCG (cD) [7-9,16-22]. Plionis et al. [23] and Rong, Zhang & Liao [24] found evidence that significant galaxy alignment is present in dynamically young clusters. Meanwhile, Dekel [25], van Kampen & Rhee
TABLE 1. The Iist of Isolated Clusters with Nearby Neighbor at Projected Distance >10 Mpc
448
Cluster
z
N2
Cluster
z
N2
Cluster
z
N2
A595
0.0666
48
A1168
0.0906
41
A1825
0.0595
30
A602
0.0619
62
A1169
0.0586
79
A1827
0.0654
41
A634
0.0265
102
A1238
0.0733
68
A1849
Data Loading...
