Chandra Observations of the Gravitational Lenses B1600+434 and B1608+656
Abstract
We observed B1600+434 and B1608+656 with Chandra ACIS, detecting both quasar images in B1600+434 and three of four images in B1608+656. We did not detect significant X-ray emission from nearby galaxy groups or clusters associated with each lens galaxy. The upper limits on the X-ray luminosity of any cluster within 4' of each lens and at each lens redshift are ~2×1042 and ~6×1042 ergs s-1 for B1600+434 and B1608+656, respectively. The radio-loud source quasars have power-law photon indices of Γ=1.9+/-0.2 and Γ=1.4+/-0.3 and X-ray luminosities of 1.4+0.2-0.1×1045 and 2.9+0.7-0.4×1044 ergs s-1 for B1600+434 and B1608+656, respectively, before correcting for the magnification. We detected a differential absorption column density of ΔNH~3×1021cm-2 between the two images of B1600+434, roughly consistent with expectations from differential extinction estimates of ΔE(B-V)=0.1 mag and a standard dust-to-gas ratio. The differential absorption observed in gravitational lenses may serve as an important probe to study the gas content in high-redshift galaxies, since it can separate the absorbing column originating from the lens galaxy and those intrinsic to quasars. We also detected 157 serendipitous X-ray sources in the two Chandra fields and identified the brighter optical counterparts using the Sloan Digital Sky Survey and Palomar Digital Sky Survey.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- June 2005
- DOI:
- 10.1086/429485
- arXiv:
- arXiv:astro-ph/0502007
- Bibcode:
- 2005ApJ...625..633D
- Keywords:
-
- Cosmology: Gravitational Lensing;
- Astrophysics
- E-Print:
- 24 pages, including 3 figures and 5 tables, accepted by ApJ