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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 661045.0, MPI für Astronomie / Publikationen_mpia
The morphologies of massive galaxies at 1<z<3 in the CANDELS-UDS Field: compact bulges, and the rise and fall of massive discs
Authors:Bruce, V. A.; Dunlop, J. S.; Cirasuolo, M.; McLure, R. J.; Targett, T. A.; Bell, E. F.; Croton, D. J.; Dekel, A.; Faber, S. M.; Ferguson, H. C.; Grogin, N. A.; Kocevski, D. D.; Koekemoer, A. M.; Koo, D. C.; Lai, K.; Lotz, J. M.; McGrath, E. J.; Newman, J. A.; van der Wel, A.
Date of Publication (YYYY-MM-DD):2012
Journal Abbrev.:Monthly Notices of the Royal Astronomical Society
Issue / Number:2
Start Page:1666
End Page:1701
Audience:Not Specified
Abstract / Description:We have used deep, HST, near-IR imaging to study the morphological properties of the most massive galaxies at high z, modelling the WFC3/IR H-band images of the ~200 galaxies in the CANDELS-UDS field with 1 < z_phot < 3, and stellar masses M_star > 10^11 M_sun. We have used both single-Sersic and bulge+disk models, have investigated the errors/biases introduced by uncertainties in the background and the PSF, and have obtained formally-acceptable model fits to >90% of the galaxies. Our results indicate that these massive galaxies at 1 < z < 3 lie both on and below the local size-mass relation, with a median R_e~2.6 kpc, a factor of ~2.3 smaller than comparably-massive local galaxies. Moreover, we find that bulge-dominated objects in particular show evidence for a growing bimodality in the size-mass relation with increasing z, and by z > 2 the compact bulges display effective radii a factor ~4 smaller than local ellipticals of comparable mass. These trends appear to extend to the bulge components of disk-dominated galaxies, and vice versa. We also find that, while such massive galaxies at low z are bulge-dominated, at 1 < z < 2 they are predominantly mixed bulge+disk systems, and by z > 2 they are mostly disk-dominated. The majority of the disk-dominated galaxies are actively forming stars, but this is also true for many of the bulge-dominated systems. Interestingly, however, while most of the quiescent galaxies are bulge-dominated, we find that a significant fraction (25-40%) of the most quiescent galaxies have disk-dominated morphologies. Thus, while our results show that the massive galaxy population is undergoing dramatic changes at this crucial epoch, they also suggest that the physical mechanisms which quench star-formation activity are not simply connected to those responsible for the morphological transformation of massive galaxies into present-day giant ellipticals.
Free Keywords:Astrophysics - Cosmology and Extragalactic Astrophysics
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
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