Structure of visible and dark matter components in spiral galaxies at redshifts z = 0.5-0.9

Abstract

We have constructed self-consistent light and mass distribution models for four disk galaxies at redshifts z = 0.48, 0.58, 0.81 and 0.88, using the HST archive WFPC2 observations and rotation curves measured by Vogt et al. (1996) and Rigopoulou et al. (2002). The models consist of three components: a bulge, a disk and a dark matter halo. Similarly to the sample studied in Paper I (Tamm & Tenjes, 2003), light distribution of the galaxies in the outer parts is clearly steeper than a simple exponential disk. After applying k-corrections, calculated mass-to-light ratios for galactic disks within the maximum disk assumption are M/L_B = 0.9, 7.4, 4.3 and 1.4, respectively. Together with the galaxies from Paper I, the mean <M/L_B> = 2.5 at <z> ~0.9, indicating no significant evolution of M/L_B with redshift. Central densities of dark matter halos for an isothermal model are 0.008, 0.035, 0.013, and 0.022 in units M_sun/pc^3, respectively. Together with the galaxies from Paper I, the DM central density of the four galaxies at mean readshift <z> ~0.9 is rho(0) = (0.012-0.028) M_sun/pc^3, also showing no significant evolution with redshift.

11 pages, 10 figures, Astron. Astrophys. accepted