%0 Generic %1 chang2012shape %A Chang, Yu-Yen %A van der Wel, Arjen %A Rix, Hans-Walter %A Wuyts, Stijn %A Zibetti, Stefano %A Ramkumar, Balasubramanian %A Holden, Bradford P. %D 2012 %K elliptical evolution mergers %T Shape Evolution of Massive Early-Type Galaxies: Confirmation of Increased Disk Prevalence at z>1 %U http://arxiv.org/abs/1211.2113 %X We use high-resolution K-band VLT/HAWK-I imaging over 0.25 square degrees to study the structural evolution of massive early-type galaxies since z~1. Mass-selected samples, complete down to log(M/M_sun)~10.7 such that `typical' L* galaxies are included at all redshifts, are drawn from pre-existing photometric redshift surveys. We then separated the samples into different redshift slices and classify them as late- or early-type galaxies on the basis of their specific star-formation rate. Axis-ratio measurements for the ~400 early-type galaxies in the redshift range 0.6<z<1.8 are accurate to 0.1 or better. The projected axis-ratio distributions are then compared with lower redshift samples. We find strong evidence for evolution of the population properties: early-type galaxies at z>1 are, on average, flatter than at z<1 and the median projected axis ratio at a fixed mass decreases with redshift. However, we also find that at all epochs z<~2 the very most massive early-type galaxies (log(M/M_sun)>11.3) are the roundest, with a pronounced lack among them of galaxies that are flat in projection. Merging is a plausible mechanism that can explain both results: at all epochs merging is required for early-type galaxies to grow beyond log(M/M_sun)~11.3, and all early types over time gradually and partially loose their disk-like characteristics.

@misc{chang2012shape, abstract = {We use high-resolution K-band VLT/HAWK-I imaging over 0.25 square degrees to study the structural evolution of massive early-type galaxies since z~1. Mass-selected samples, complete down to log(M/M_sun)~10.7 such that `typical' L* galaxies are included at all redshifts, are drawn from pre-existing photometric redshift surveys. We then separated the samples into different redshift slices and classify them as late- or early-type galaxies on the basis of their specific star-formation rate. Axis-ratio measurements for the ~400 early-type galaxies in the redshift range 0.6<z<1.8 are accurate to 0.1 or better. The projected axis-ratio distributions are then compared with lower redshift samples. We find strong evidence for evolution of the population properties: early-type galaxies at z>1 are, on average, flatter than at z<1 and the median projected axis ratio at a fixed mass decreases with redshift. However, we also find that at all epochs z<~2 the very most massive early-type galaxies (log(M/M_sun)>11.3) are the roundest, with a pronounced lack among them of galaxies that are flat in projection. Merging is a plausible mechanism that can explain both results: at all epochs merging is required for early-type galaxies to grow beyond log(M/M_sun)~11.3, and all early types over time gradually and partially loose their disk-like characteristics.}, added-at = {2012-11-12T15:34:30.000+0100}, author = {Chang, Yu-Yen and van der Wel, Arjen and Rix, Hans-Walter and Wuyts, Stijn and Zibetti, Stefano and Ramkumar, Balasubramanian and Holden, Bradford P.}, biburl = {https://www.bibsonomy.org/bibtex/2efe32623f40b4906c5a29f7df82aa246/miki}, description = {[1211.2113] Shape Evolution of Massive Early-Type Galaxies: Confirmation of Increased Disk Prevalence at z&gt;1}, interhash = {80a7f9eda5e2d66963674f057d0e38ac}, intrahash = {efe32623f40b4906c5a29f7df82aa246}, keywords = {elliptical evolution mergers}, note = {cite arxiv:1211.2113Comment: accepted for publication in ApJ; 11 pages; 10 figures; 4 tables}, timestamp = {2012-11-12T15:34:30.000+0100}, title = {Shape Evolution of Massive Early-Type Galaxies: Confirmation of Increased Disk Prevalence at z>1}, url = {http://arxiv.org/abs/1211.2113}, year = 2012 }