EDP Sciences
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Volume 433, Number 1, April I 2005
Page(s) 31 - 41
Section Cosmology (including clusters of galaxies)
DOI http://dx.doi.org/10.1051/0004-6361:20041879

A&A 433, 31-41 (2005)
DOI: 10.1051/0004-6361:20041879

Structure of visible and dark matter components in spiral galaxies at redshifts z $\mathsf{= 0.5{-}0.9}$

A. Tamm1 and P. Tenjes1, 2

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)

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 (HDF-S, MDS, Groth Strip survey) 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/LB = 0.9, 7.4, 4.3 and 1.4, respectively. Together with the galaxies from Paper I, the mean $\langle M/L_B\rangle =$ 2.5 at $\langle
z\rangle \simeq 0.9$, indicating no significant evolution of M/LB with redshift. Central densities of dark matter halos for an isothermal model are 0.008, 0.035, 0.013, and 0.022 in units  $M_{\odot} /{\rm pc}^3,$ respectively. Together with the galaxies from Paper I, the DM central density of the four galaxies at mean readshift $\langle
z\rangle \simeq 0.9$ is $\rho (0) =
(0.012{-}0.028)~M_{\odot}/{\rm pc}^3,$ 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.

Key words: galaxies: photometry -- galaxies: fundamental parameters -- galaxies: high-redshift -- galaxies: spiral -- galaxies: structure -- dark matter

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