GOLDEN GRAVITATIONAL LENSING SYSTEMS FROM THE SLOAN LENS ACS SURVEY. I. SDSS J1538+5817: ONE LENS FOR TWO SOURCES ,
- Max-Planck-Institut fuer extraterrestrische Physik, Giessenbachstr., D-85748 Garching (Germany)
- Universitaets-Sternwarte Muenchen, Scheinerstr. 1, D-81679 Muenchen (Germany)
- European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching (Germany)
- CEA Saclay, DSM/DAPNIA/Service d'Astrophysique, F-91191 Gif-sur-Yvette Cedex (France)
We present a gravitational lensing and photometric study of the exceptional strong lensing system SDSS J1538+5817, identified by the Sloan Lens Advanced Camera for Survey. The lens is a luminous elliptical galaxy at redshift z{sub l} = 0.143. Using Hubble Space Telescope public images obtained with two different filters, the presence of two background sources lensed, respectively, into an Einstein ring and a double system is ascertained. Our new spectroscopic observations, performed at the Nordic Optical Telescope, reveal unequivocally that the two sources are located at the same redshift z{sub s} = 0.531. We investigate the total (luminous and dark) mass distribution of the lens between 1 and 4 kpc from the galaxy center by means of parametric and non-parametric lensing codes that describe the multiple images as point-like objects. Bootstrapping and Bayesian analyses are performed to determine the uncertainties on the quantities relevant to the lens mass characterization. Several disparate lensing models provide results that are consistent, given the errors, with those obtained from the best-fit model of the lens mass distribution in terms of a singular power-law ellipsoid model. In particular, the lensing models agree on: (1) reproducing accurately the observed positions of the images; (2) predicting a nearly axisymmetric total mass distribution, centered and oriented as the light distribution; (3) measuring a value of 8.11{sup +0.27}{sub -0.59} x 10{sup 10} M{sub sun} for the total mass projected within the Einstein radius of 2.5 kpc; and (4) estimating a total mass density profile slightly steeper than an isothermal one (rho(r){proportional_to}r{sup -2.33+0.43{sub -0.20}}). A fit of the Sloan Digital Sky Survey multicolor photometry with composite stellar population models provides a value of 20{sup +1}{sub -4} x 10{sup 10} M{sub sun} for the total mass of the galaxy in the form of stars and of 0.9{sup +0.1}{sub -0.2} for the fraction of projected luminous over total mass enclosed inside the Einstein radius. By combining lensing (total) and photometric (luminous) mass measurements, we differentiate the lens mass content in terms of luminous and dark matter components. This two-component modeling, which is viable only in extraordinary systems like SDSS J1538+5817, leads to a description of the global properties of the galaxy dark matter halo. Extending these results to a larger number of lens galaxies would considerably improve our understanding of galaxy formation and evolution processes in the LAMBDACDM scenario.
- OSTI ID:
- 21394502
- Journal Information:
- Astrophysical Journal, Vol. 710, Issue 1; Other Information: DOI: 10.1088/0004-637X/710/1/372; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
Similar Records
PROJECTED CENTRAL DARK MATTER FRACTIONS AND DENSITIES IN MASSIVE EARLY-TYPE GALAXIES FROM THE SLOAN DIGITAL SKY SURVEY
DISCOVERY OF A VERY BRIGHT, STRONGLY LENSED z = 2 GALAXY IN THE SDSS DR5