Abstract
Deep spectroscopy of the two Leiden-Berkeley Deep Survey mJy radio
galaxies LBDS 53W069 and 53W091 has previously shown them to have old
(>~3 Gyr) stellar populations at z~= 1.5. Here we present the results
of Hubble Space Telescope (HST) observations with the Wide Field and
Planetary Camera 2 (WFPC2) in F814W and with the Near-Infrared Camera
and Multi-Object Spectrograph (NICMOS) in F110W. We find that 53W069 has
a de Vaucouleurs r1/4 profile in both the F814W and F110W
data, with a mean effective radius of 0.30 +/- 0.06 arcsec (2.7 +/- 0.5
kpc). The rest-frame U-B colour gradient is consistent with that of
present-day ellipticals, requiring a stellar population of supersolar (3
Zsolar) metallicity that formed on a very short time-scale at
high redshift (z > 5). 53W091 has a regular r1/4 profile
in F110W with an effective radius of 0.32 +/- 0.08 arcsec (2.9 +/- 0.7
kpc). The F814W profile is more extended and is consistent with the
presence of a blue exponential disc that contributes 20 +/- 10 per cent
of the flux within re. We find a rest-frame U-B colour
gradient that is significantly larger than that observed in field
ellipticals at z
Original language | English |
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Pages (from-to) | 1342-1350 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 336 |
DOIs | |
Publication status | Published - 1 Nov 2002 |