The Θ-z relation for HST1 bulges and disks out to z ≃ 0.8

Steven B. Mutz, Rogier Windhorst, Paul C. Schmidtke, Sebastian M. Pascarelle, Richard E. Griffiths, Kavan U. Ratnatunga, Stefano Casertano, Myungshin Im, Richard S. Ellis, Karl Glazebrook, Richard F. Green, Vicki L. Sarajedini

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


We present HST scale lengths and ground-based redshifts for 63 faint field galaxies down to 1 ≲ 21.5 mag from the Medium-Deep Survey. These have measured redshifts z ≲ 0.8 and half-light radii 0″.1 ≲ re, rs ≲ 5″. We present the Θ-z relation for r1/4-bulges and exponential disks separately for world models with q0 = 0.0-1.0. We show that selection against low surface brightness galaxies in the HST images and ground-based spectra is comparable to that in local surveys. We compare our HST disk-dominated galaxies to a magnitude-limited subsample of the ESO-Uppsala local spirals. Extrapolating the best-fit local exponential disk scale length (rs = 3.5 kpc for H0 = 75) out to z = 0.8, we find a rather symmetrical distribution of HST disks around this value. This implies that galaxy disks have been stable since z ≃ 0.8. We compare our HST bulge-dominated galaxies with r1/4-profiles to a magnitude-limited subsample of local Seven Samurai ellipticals. The latter have a local best fit re = 5.7 kpc. Our HST bulge sample shows a similar distribution for z ≲ 0.8. Elliptical galaxy scale lengths have thus also remained rather constant since z ≲ 0.8. We set limits to their possible evolution.

Original languageEnglish (US)
Pages (from-to)L55-L58
JournalAstrophysical Journal
Issue number2 PART 2
StatePublished - Oct 20 1994


  • Galaxies: distances and redshifts
  • Galaxies: evolution
  • cosmology: observations

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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