Determining the time delays in the gravitational lens PG 1115+080
Abstract
A statistical analysis of published long-term photometric monitoring observations of the gravitationally lensed quasar PG 1115+080 in the optical is presented. This goal of this study is determining the time delay between variability of the quasar manifest in its various images. Light curves of the components of PG 1115+080 obtained in 2001-2006 at the Maidanak Observatory (Uzbekistan) are considered. A linear trend is observed in the light curves of all four components during 2006, with rapid brightness variations observed only in components A1 and C. This could be a consequence of microlensing or observational errors. Application of a modified cross-correlation method to the photometric data obtained in 2004-2005 yields the time delays τ BC = 22{-3/+2} days, τ AC = 12{-1/+2} days, and τ BA = 10{-3/+2} days, in agreement with results obtained earlier by Schechter et al. and Barkana for 1995-1996 light curves using two different statistical-analysis methods. However, the new values of τ BA and τ BC differ from those obtained by Vakulik et al. using the same Maidanak Observatory data. The ratio τ AC/ τ BA ∼1.2, which is close to the values obtained by Barkana (∼1.13) and predicted by lens models (∼1.4); these differ from the values obtained by Schechter et al. (∼0.7) and Vakulik et al. (∼2.7).
- Publication:
-
Astronomy Reports
- Pub Date:
- January 2015
- DOI:
- 10.1134/S1063772915010084
- Bibcode:
- 2015ARep...59...12S