Bar Evolution over the Last 8 Billion Years: A Constant Fraction of Strong Bars in the GEMS Survey
Jogee, Shardha; Barazza, Fabio D.; Rix, Hans-Walter;Shlosman, Isaac; Barden, Marco; Wolf, Christian;Davies, James; Heyer, Inge; Beckwith, Steven V. W.;Bell, Eric F.; Borch, Andrea; Caldwell, John A. R.;Conselice, Christopher J.; Dahlen, TomasHäussler, Boris; Heymans, Catherine; Jahnke, Knud;Knapen, Johan H.; Laine, Seppo; Lubell, Gabriel M.;Mobasher, Bahram; McIntosh, Daniel H.;Meisenheimer, Klaus; Peng, Chien Y.;Ravindranath, Swara; Sanchez, Sebastian F.;Somerville, Rachel S.; Wisotzki, Lutz. Bar Evolution over the Last 8 Billion Years: A Constant Fraction of Strong Bars in the GEMS Survey. The Astrophysical Journal. 2004, Vol. Volume 615, Issue 2, pp. L105-L108, p. -2004.
and would be easily missed in earlier surveys without the small point-spread function of ACS. The bars that we can reliably detect are fairly strong (with ellipticities e>=0.4) and have a in the range ~1.2-13 kpc. We find that the optical fraction of such strong bars remains at ~30%+/-6% from the present day out to look-back times of 2-6 Gyr (z~0.2-0.7) and 6-8 Gyr (z~0.7-1.0) it certainly shows no sign of a drastic decline at z>0.7. Our findings of a large and similar bar fraction at these three epochs favor scenarios in which cold gravitationally unstable disks are already in place by z~1 and where on average bars have a long lifetime (well in excess of 2 Gyr). The distributions of structural bar properties in the two slices are, however, not statistically identical and therefore allow for the possibility that the bar strengths and sizes may evolve over time.
and would be easily missed in earlier surveys without the small point-spread function of ACS. The bars that we can reliably detect are fairly strong (with ellipticities e>=0.4) and have a in the range ~1.2-13 kpc. We find that the optical fraction of such strong bars remains at ~30%+/-6% from the present day out to look-back times of 2-6 Gyr (z~0.2-0.7) and 6-8 Gyr (z~0.7-1.0) it certainly shows no sign of a drastic decline at z>0.7. Our findings of a large and similar bar fraction at these three epochs favor scenarios in which cold gravitationally unstable disks are already in place by z~1 and where on average bars have a long lifetime (well in excess of 2 Gyr). The distributions of structural bar properties in the two slices are, however, not statistically identical and therefore allow for the possibility that the bar strengths and sizes may evolve over time.