Astronomy and Astrophysics – Astronomy
Scientific paper
Jun 2006
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2006rmxac..26r.186a&link_type=abstract
XI IAU Regional Latin American Meeting of Astronomy (Eds. L. Infante & M. Rubio) Revista Mexicana de Astronomía y Astrofísica (S
Astronomy and Astrophysics
Astronomy
Scientific paper
We inspected DSS images of 1083 Abell clusters likely to have a dominant galaxy, and derived accurate positions for BCM candidates, as well as ellipticities using IRAF's ellipse. We retrieved the BCM's basic parameters from NED, and extracted cluster mean redshifts, z_{cl}, and velocity dispersions, σ_{cl}, from the compilation maintained by two of us (Andernach et al.005, ASPCS 329, 283). We include only clusters with at least 10 measured redshifts, yielding a sample of 385 BCMs in 326 Abell clusters. For these we derived the relative velocity offset, v_{off}/σ_{cl} = (v_{BCM} - cz_{cl})/(1 + z_{cl})/σ_{cl} , where v_{BCM} is the BCM radial velocity. Half of the BCMs in our sample move at peculiar velocities above 0.37 σ_{cl}, with a trend for a smaller v_{off}/σ_{cl} in richer clusters which is expected if the latter are dynamically more evolved. For a sample of 980 BCMs the median ellipticity of the BCM's outer envelopes <ɛ> rises with Abell richness, such that <ɛ>=0.19 for the 559 R=0 clusters, <ɛ>=0.22 for 276 R=1 clusters, and <ɛ>=0.26 for 145 R ≥ 2 clusters. A Kolmogorov-Smirnov test for the ellipticity distributions yields probabilities of p=0.016 for the R=0 and R=1 samples, and p<0.0005 for the R=0 and R≥2 samples to be drawn from the same population. This may suggest that BCMs in richer clusters grow more likely by anisotropic mergers. Our findings support Merritt's model (1985, ApJ 289, 18) in which most BCMs form during the collapse and virialization of poor clusters or compact groups with low velocity dispersions. We show that this model seems to apply to all BCMs, not only to cD galaxies. This supports the view that most galaxies formed in groups (and not in rich clusters) with a common dark halo and/or individual halo of each galaxy which form(s) a local potential minimum for BCM.
Alamo-Martinez K.
Andernach Heinz
Coziol Roger
Tago Erik
No associations
LandOfFree
Dynamics and ellipticities of brightest cluster galaxies does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Dynamics and ellipticities of brightest cluster galaxies, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Dynamics and ellipticities of brightest cluster galaxies will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1479570