paper

H-Band and Spectroscopic Properties of Abell 1644

arXiv:astro-ph/0104397 · doi:10.1086/322121

Abstract

We discuss H-band (1.65 micrometer) near-infrared photometry of the central 3x3h^{-2} Mpc^2 of Abell 1644 to a limiting M_H~M^*_H+3 (throughout this paper H_0=100 h km s^{-1} Mpc^{-1}). There are 861 galaxies in the photometric survey region. We also measured radial velocities of 155 galaxies; 141 of these are cluster members within 2.44 h^{-1} Mpc of the cluster center. The cluster velocity dispersion of sigma~1000 km s^{-1} remains constant out to the limiting radius. We find no evidence for substructure in the cluster. The cluster mass within R=2.4 h^{-1} Mpc is 7.6+-1.3x10^{14} h^{-1} M_\odot. We compute the cluster luminosity function; the Schechter parameters α=-1.14\pm0.08 and M^*_H=-24.3\pm0.2 (with h=0.5) agree well with other H-band luminosity functions. From the virial theorem and the caustic method we compute one of the first mass-to-light ratios at H; the result is M/L_H=82-127 h M_\odot/L_\odot within 1.5 h^{-1} Mpc. This ratio corresponds to 374-579 h M_\odot/L_\odot at R. The agreement of our IR measurement with previous determinations indicates that at low redshift dust and young stellar populations may produce only negligible systematic errors in optical mass-to-light ratios.

30 pages, 12 figures, 2 tables. Revised version (2 figures removed; discussion of background expanded; other minor corrections). Accepted for publication in the Astronomical Journal

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