S.S. Allam, H. Lin, D. L. Tucker, H. Diehl,
J. Annis, L. Buckley-Geer, J. Frieman
We report to the SDSS collaboration the discovery and spectroscopic
confirmation of four gravitationally lensed images of a Lyman break
galaxy (LBG) at a redshift of 2.73 in the background of a relatively
nearby (z=0.38) SDSS luminous red galaxy (LRG), on the basis of SPICAM
and DISIII observations carried out on August 23, 2006 on the ARC 3.5m
telescope at Apache Point Observatory.
This LBG, which we have dubbed the "8 o'clock arc", shares many
characteristics with the well-known lensed LBG cB58 (Yee et al. 1996),
including coincidentally very similar source and lens redshifts.
However, the 8 o'clock arc is a factor of three brighter than cB58.
This makes the 8 o'clock arc the brightest LBG known, thanks to its
magnification by the lensing galaxy.
We have modeled this system with the gravlens/lensmodel software
(Keeton 2000) using a singular isothermal ellipsoid, which can account
for the observed positions and fluxes in the 4-image configuration.
In particular, we derive an Einstein radius of 2.91 arcsec+/- 0.14, a
total magnification factor >10.
Date Nov 7, 2006
An ApJ Letter reporting this discovery will be available.
An SDSS press release will be available at sdss.org
Images:
The 8 O'Clock Arc SDSS 2.5 m color images in jpg and jpeg format.
The 8 O'Clock Arc APO 3.5 m g-band B/W images in jpg and jpeg format.
The 8 O'Clock Arc APO 3.5 m spectra in jpg and jpeg format.
Email: sallam@fnal.gov
