Evolution and Impact of Bars over the last nine Gyr: Early Results from GEMS

Jogee, S.; Barazza, F. D.; Rix, H.-W.; Davies, J.;Heyer, I.; Barden, M.; Beckwith, S. V. W.;Bell, E. F.; Borch, A.; Caldwell, J. A. R.;Conselice, C.; Häussler, B.; Heymans, C.; Jahnke, K.;Knapen, J. H.; Laine, S.; Lubell, G. M.;Mobasher, B.; McIntosh, D. H.; Meisenheimer, K.;Peng, C. Y.; Ravindranath, S.; Sanchez, S. F.;Shlosman, I.; Somerville, R. S.; Wisotzki, L.;Wolf, C.. Evolution and Impact of Bars over the last nine Gyr: Early Results from GEMS. Penetrating bars through masks of cosmic dust : the Hubble tuning fork strikes a new note, Proceedings of a conference held at Pilanesburg National Park (South Africa). Edited by D. L. Block, I. Puerari, K. C. Freeman, R. Groess, and E. K. Block. Astrophysics and space science library (ASSL) vol. 319. Dordrecht: Kluwer Academic Publishers, 2004, p.291. 2004, Vol. , p. -2004.

Bars drive the dynamical evolution of disk galaxies by redistributing mass and angular momentum, and they are ubiquitous in present-day spirals. Early studies of the Hubble Deep Field reported a dramatic decline in the rest-frame optical bar fraction f_opt to below 5% at redshifts z>0.7, implying that disks at these epochs are fundamentally different from present-day spirals. The GEMS bar project, based on ~8300 galaxies with HST-based morphologies and accurate redshifts over the range 0.2-1.1, aims at constraining the evolution and impact of bars over the last 8 Gyr. We present early results indicating that f_opt remains nearly constant at ~30% over the range z=0.2-1.1,corresponding to lookback times of ~2.5-8 Gyr. The bars detected at z>0.6 are primarily strong with ellipticities of 0.4-0.8. Remarkably, the bar fraction and range of bar sizes observed at z>0.6 appear to be comparable to the values measured in the local Universe for bars of corresponding strengths. Implications for bar evolution models are discussed.