Abstract
We report the discovery of a massive ultracompact quiescent galaxy that
has been strongly lensed into multiple images by a foreground galaxy at
z = 0.960. This system was serendipitously discovered as a set of
extremely Ks -bright high-redshift galaxies with red J
- Ks colors using new data from the UltraVISTA
YJHKs near-infrared survey. The system was also previously
identified as an optically faint lens/source system using the COSMOS
Advanced Camera for Surveys (ACS) imaging by Faure et al. Photometric
redshifts for the three brightest images of the source galaxy determined
from 27-band photometry place the source at z = 2.4 ± 0.1. We
provide an updated lens model for the system that is a good fit to the
positions and morphologies of the galaxies in the ACS image. The lens
model implies that the magnification of the three brightest images is a
factor of 4-5. We use the lens model, combined with the Ks
-band image, to constrain the size and Sérsic profile of the
galaxy. The best-fit model is an ultracompact galaxy (Re =
0.64+0.08 - 0.18 kpc, lensing-corrected),
with a Sérsic profile that is intermediate between a disk and a
bulge profile (n = 2.2+2.3 - 0.9), albeit
with considerable uncertainties on the Sérsic profile. We present
aperture photometry for the source galaxy images that have been
corrected for flux contamination from the central lens. The best-fit
stellar population model is a massive galaxy (log(M star/M
⊙) = 10.8+0.1 - 0.1,
lensing-corrected) with an age of 1.0+1.0 -
0.4 Gyr, moderate dust extinction (Av =
0.8+0.5 - 0.6), and a low specific star
formation rate (log(SSFR)
| Original language | English |
|---|---|
| Pages (from-to) | 142 |
| Journal | Astrophysical Journal |
| Volume | 761 |
| Publication status | Published - 1 Dec 2012 |
Keywords
- galaxies: evolution
- galaxies: fundamental parameters
- galaxies: high-redshift
- galaxies: structure
- infrared: galaxies