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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 448122.0, MPI für Astronomie / Publikationen_mpia
Early-type galaxies in the PEARS Survey: Probing the stellar populations at moderate redshift
Authors:Ferreras, Ignacio; Pasquali, Anna; Malhotra, Sangeeta; Rhoads, James; Cohen, Seth; Windhorst, Rogier; Pirzkal, Nor; Grogin, Norman; Koekemoer, Anton M.; Lisker, Thorsten; Panagia, Nino; Daddi, Emanuele; Hathi, Nimish P.
Date of Publication (YYYY-MM-DD):2009
Title of Journal:The Astrophysical Journal
Journal Abbrev.:ApJ
Issue / Number:1
Start Page:158
End Page:169
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:Using Hubble Space Telescope (HST)/Advanced Camera for Surveys (ACS) slitless grism spectra from the PEARS program, we study the stellar populations of morphologically selected early-type galaxies in the GOODS North and South fields. The sample—extracted from a visual classification of the (v2.0) HST/ACS images and restricted to redshifts z > 0.4—comprises 228 galaxies (i F775W < 24 mag, AB) out to z lsim 1.3 over 320 arcmin2, with a median redshift z M = 0.75. This work significantly increases our previous sample from the GRAPES survey in the HUDF (18 galaxies over ~11 arcmin2). The grism data allow us to separate the sample into "red" and "blue" spectra, with the latter comprising 15% of the total. Three different grids of models parameterizing the star formation history are used to fit the low-resolution spectra. Over the redshift range of the sample—corresponding to a cosmic age between 5 and 10 Gyr—we find a strong correlation between stellar mass and average age, whereas the spread of ages (defined by the root mean square of the distribution) is roughly ~1 Gyr and independent of stellar mass. The best-fit parameters suggest that it is the formation epoch and not the formation timescale that best correlates with mass in early-type galaxies. This result—along with the recently observed lack of evolution of the number density of massive galaxies—motivates the need for a channel of (massive) galaxy formation bypassing any phase in the blue cloud, as suggested by the simulations of Dekel et al.
Free Keywords:galaxies: elliptical and lenticular; cD; galaxies: evolution; galaxies: stellar content
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:URL:http://adsabs.harvard.edu/abs/2009ApJ...706..158F [ID No:1]
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