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EnglishWe study the internal dynamics of the rich galaxy cluster ABGC 209 on the basis of new spectroscopic and photometric data. The distribution in redshift shows that ABCG 209 is a well isolated peak of 112 detected member galaxies at z=0.209, characterised by a high value of the line-of-sight velocity dispersion, sigma_v=1250-1400 km s-1, on the whole observed area (1 h-1 Mpc; from the cluster center), that leads to a virial mass of M=1.6-2.2× 1015 Msun within the virial radius, assuming the dynamical equilibrium. The presence of a velocity gradient in the velocity field, the elongation in the spatial distribution of the colour-selected likely cluster members, the elongation of the X-ray contour levels in the Chandra image, and the elongation of cD galaxy show that ABCG 209 is characterised by a preferential NW-SE direction. We also find a significant deviation of the velocity distribution from a Gaussian, and relevant evidence of substructure and dynamical segregation. All these facts show that ABCG 209 is a strongly evolving cluster, possibly in an advanced phase of merging. Based on observations collected at the European Southern Observatory, Chile (Proposal ESO No 68.A-0116).
| Titolo: | Structure and Evolution of Galaxy Clusters: Internal Dynamics of ABCG 209 at z$sim$0.21 |
| Autori: | |
| Data di pubblicazione: | 2003 |
| Rivista: | |
| Abstract: | We study the internal dynamics of the rich galaxy cluster ABGC 209 on the basis of new spectroscopic and photometric data. The distribution in redshift shows that ABCG 209 is a well isolated peak of 112 detected member galaxies at z=0.209, characterised by a high value of the line-of-sight velocity dispersion, sigma_v=1250-1400 km s-1, on the whole observed area (1 h-1 Mpc; from the cluster center), that leads to a virial mass of M=1.6-2.2× 1015 Msun within the virial radius, assuming the dynamical equilibrium. The presence of a velocity gradient in the velocity field, the elongation in the spatial distribution of the colour-selected likely cluster members, the elongation of the X-ray contour levels in the Chandra image, and the elongation of cD galaxy show that ABCG 209 is characterised by a preferential NW-SE direction. We also find a significant deviation of the velocity distribution from a Gaussian, and relevant evidence of substructure and dynamical segregation. All these facts show that ABCG 209 is a strongly evolving cluster, possibly in an advanced phase of merging. Based on observations collected at the European Southern Observatory, Chile (Proposal ESO No 68.A-0116). |
| Handle: | http://hdl.handle.net/11368/1695168 |
| Digital Object Identifier (DOI): | http://dx.doi.org/10.1051/0004-6361:20021495 |
| URL: | http://adsabs.harvard.edu/abs/2003A%26A...397..431M |
| Appare nelle tipologie: | 1.1 Articolo in Rivista |
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