The galaxy population of the z= 1 cluster of galaxies MG2016+112
Abstract
A photometric redshift analysis of galaxies in the field of the wide-separation gravitational lens MG2016+112 reveals a population of 69 galaxies with photometric redshifts consistent with being in a cluster at the redshift of the giant elliptical lensing galaxy z= 1.00. The Ks-band luminosity function of the cluster galaxies is well represented by the Schechter function with a characteristic magnitude K*s= 18.90+0.45-0.57 and faint-end slope α=-0.60+0.39-0.33, consistent with what is expected for a passively evolving population of galaxies formed at high redshift, zf > 2. From the total Ks-band flux of the cluster galaxies and a dynamical estimate of the total mass of the cluster, the rest-frame Ks-band mass-to-light ratio of the cluster is derived to be M/LKs= 27+64-17h50(M/LKs)solar, in agreement with the upper limit derived earlier from Chandra X-ray observations and the value derived locally in the Coma cluster. The cluster galaxies span a red sequence with a considerable scatter in the colour-magnitude diagrams, suggesting that they contain young stellar populations in addition to the old populations of main-sequence stars that dominate the Ks-band luminosity function. This is in agreement with spectroscopic observations which show that 5 out of the 6 galaxies in the field confirmed to be at the redshift of the lensing galaxy have emission lines. The projected spatial distribution of the cluster galaxies is filamentary-like rather than centrally concentrated around the lensing galaxy, and shows no apparent luminosity segregation. A handful of the cluster galaxies show evidence of merging/interaction. The results presented in this paper suggest that a young cluster of galaxies is assembling around MG2016+112.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- September 2003
- DOI:
- 10.1046/j.1365-8711.2003.06589.x
- arXiv:
- arXiv:astro-ph/0303066
- Bibcode:
- 2003MNRAS.344..337T
- Keywords:
-
- galaxies: clusters: individual: MG2016+112;
- galaxies: elliptical and lenticular;
- cD;
- galaxies: evolution;
- galaxies: formation;
- galaxies: luminosity function;
- mass function;
- cosmology: observations;
- Astrophysics
- E-Print:
- Accepted for publication in MNRAS