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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents



ID: 693833.0, MPI für Astronomie / Publikationen_mpia
Shape evolution of massive early-type galaxies: Confirmation of increased disk prevalence at z>1
Authors:Chang, Y.-Y.; van der Wel, A.; Rix, H.-W.; Wuyts, S.; Zibetti, S.; Ramkumar, B.; Holden, B. P.
Date of Publication (YYYY-MM-DD):2013
Title of Journal:The Astrophysical Journal
Volume:762
Issue / Number:2
Start Page:id. 83 (9 pp)
Audience:Not Specified
Abstract / Description: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.
Free Keywords:Astrophysics - Cosmology and Extragalactic Astrophysics
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:URL:http://cdsads.u-strasbg.fr/abs/2012arXiv1211.2113C
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