Structure of visible and dark matter components in spiral galaxies at redshifts z

¹ Institute of Theoretical Physics, Tartu University, Tähe 4, Tartu 51010, Estonia e-mail: [atamm;ptenjes]@ut.ee
² Tartu Observatory, Tõravere, Tartumaa 61602, Estonia

Received: 23 August 2004
Accepted: 29 November 2004

Abstract

We have constructed self-consistent light and mass distribution models for four disk galaxies at redshifts 0.58, 0.81 and 0.88, using the HST archive WFPC2 observations (HDF-S, MDS, Groth Strip survey) and rotation curves measured by Vogt et al. ([CITE]) and Rigopoulou et al. ([CITE]). 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 [CITE]), 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 0.9, 7.4, 4.3 and 1.4, respectively. Together with the galaxies from Paper I, the mean 2.5 at , indicating no significant evolution of  with redshift. Central densities of dark matter halos for an isothermal model are 0.008, 0.035, 0.013, and 0.022 in units  respectively. Together with the galaxies from Paper I, the DM central density of the four galaxies at mean readshift is also showing no significant evolution with redshift.
We have also constructed mass distribution models without assuming flat rotation curves and without a dark matter component. Due to the limited extent of the observed rotation, the models without a dark halo nearly fit the observations. In this case, mass-to-light ratios for the galactic disks are 1.8, 9.7, 12. and 1.9, respectively.