Dark Matter in MS 1224 from Distortion of Background Galaxies
Abstract
We explore the dark matter distribution in MS 1224.7+2007 using the gravitational distortion of the images of faint background galaxies. Projected mass image reconstruction reveals a highly significant concentration coincident with the Xray and optical location. The concentration is seen repeatably in reconstructions from independent subsamples, and the azimuthally averaged tangential shear pattern is also clearly seen in the data. The projected mass within a 2.76' radius aperture is ~3.5 x 10^14^ h^1^ M_sun_. This is ~3 times larger than that predicted if mass traces light with M/L = 275 as derived from virial analysis. It is very hard to attribute the discrepancy to a statistical fluctuation, and a further indication of a significant difference between the mass and the light comes from a second mass concentration, which is again seen in independent subsamples but which is not seen at all in the cluster light. We find a mass per galaxy visible to I = 22 of ~8 x 10^12^ h^1^ M_sun_, which, if representative of the universe, implies a density parameter {OMEGA}~2. We find a null detection of any net shear from largescale structure with a precision of 0.9% per component. This is much smaller than the possible detection in a recent comparable study, and the precision here is at about the level of the rms shear fluctuations in realistic models.
 Publication:

The Astrophysical Journal
 Pub Date:
 December 1994
 DOI:
 10.1086/174974
 arXiv:
 arXiv:astroph/9402017
 Bibcode:
 1994ApJ...437...56F
 Keywords:

 Astronomical Models;
 Cosmology;
 Dark Matter;
 Galactic Clusters;
 Gravitational Lenses;
 Image Reconstruction;
 Mass Distribution;
 Density Distribution;
 Image Processing;
 Mathematical Models;
 Size Distribution;
 Spatial Distribution;
 Astrophysics;
 Astrophysics;
 High Energy Physics  Phenomenology
 EPrint:
 8 pages (no figures), latex, CITA/94/4, postscript file with figures available by anonymous ftp in /cita/nick/ms1224/ at ftp.cita.utoronto.ca