Infrared mass-to-light profile throughout the infall region of the Coma Cluster

Using a redshift survey of 1779 galaxies and photometry from the Two Micron All Sky Survey covering 200 deg(2), we calculate independent mass and light profiles for the infall region of the Coma Cluster of galaxies. The redshift survey is complete to K(s) = 12.2 (622 galaxies), 1.2 mag fainter than M(Ks)*at the distance of Coma. We confirm the mass profile obtained by Geller, Diaferio, and Kurtz. The enclosed mass-to-light ratio measured in the K(s) band is approximately constant to a radius of 10 h(-1) Mpc, where M/L(Ks) = 75 +/- 23 h M./L., in agreement with weak-lensing results on similar scales. Within 2.5 h(-1) Mpc, X-ray estimates yield similar mass-to-light ratios (67 +/- 32 h). The constant enclosed mass-to-light ratio with radius suggests that the K-band light from bright galaxies in clusters traces the total mass on scales less than or similar to 10 h(-1) Mpc. Uncertainties in the mass profile imply that the mass-to-light ratio inside r(200) may be as much as a factor of 2.5 larger than that outside r(200). These data demonstrate that the K-band light is not positively biased with respect to the mass; we cannot rule out antibias. These results imply that Omega (m) = 0.17 +/- 0/05. Estimates of possible variations in M/L(Ks) with radius suggest that the density parameter is no smaller than Omega (m) approximate to 0.08.