Structure and mass distribution of spiral galaxies at intermediate redshifts

Abstract

Using the HST archive WFPC2 observations and rotation curves measured by Vogt et al. (\cite{vogt1}), we constructed self-consistent light and mass distribution models for three disk galaxies at redshifts z=0.15, 0.90 and 0.99. The models consist of three components: the bulge, the disk and the dark matter. The light distribution of the galaxies in the outer parts is steeper than a simple exponential disk. Spatial density distribution parameters for the components were calculated. After applying k-corrections, mass-to-light ratios for galactic disks within the maximum disk assumption are M/L_B = 4.4, 1.2 and 1.2, respectively. Corresponding central densities of dark matter halos within a truncated isothermal model are 0.0092, 0.028 and 0.015 in units M_sun /pc³. In addition, we constructed mass distribution models without a dark matter component. Due to the limited extent of rotational curves the models without a dark halo fit equally well with observations. In this case mass-to-light ratios for galactic disks are 5.5, 3.3 and 2.1, respectively.