ACS Observations of a Strongly Lensed Arc in a Field Elliptical
Abstract
We report the discovery of a strongly lensed arc system around a field elliptical galaxy in Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) images of a parallel field observed during NICMOS observations of the HST Ultra-Deep Field. The ACS parallel data comprise deep imaging in the F435W, F606W, F775W, and F850LP bandpasses. The main arc is at a radius of 1.6 arcsec from the galaxy center and subtends about 120 deg. Spectroscopic follow-up at Magellan Observatory yields a redshift z=0.6174 for the lensing galaxy, and we photometrically estimate z_phot = 2.4\pm0.3 for the arc. We also identify a likely counter-arc at a radius of 0.6 arcsec, which shows structure similar to that seen in the main arc. We model this system and find a good fit to an elliptical isothermal potential of velocity dispersion \kms, the value expected from the fundamental plane, and some external shear. Several other galaxies in the field have colors similar to the lensing galaxy and likely make up a small group.
Cite
@article{arxiv.astro-ph/0312511,
title = {ACS Observations of a Strongly Lensed Arc in a Field Elliptical},
author = {J. P. Blakeslee and K. C. Zekser and N. Benitez and M. Franx and R. L. White and H. C. Ford and R. J. Bouwens and L. Infante and N. J. Cross and G. Hertling and B. P. Holden and G. D. Illingworth and V. Motta and F. Menanteau and G. R. Meurer and M. Postman and P. Rosati and W. Zheng},
journal= {arXiv preprint arXiv:astro-ph/0312511},
year = {2009}
}
Comments
Accepted for publication in ApJ Letters. 10 pages, 3 figures. Figures have been degraded to meet size limit; a higher resolution version and addtional pictures available at http://acs.pha.jhu.edu/~jpb/UDFparc/