21 research outputs found
Is there a caustic crossing in the lensed quasar Q2237+0305 observational data record?
We re-investigate the gravitationally lensed system Q2237+0305 data record to
quantify the probability of having a caustic crossing in the A component.
Several works assume that this is the case, but no quantitative analysis is
available in the literature. We combine the datasets from the OGLE and GLITP
collaborations to accurately trace the prominent event in the lightcurve for
the A component of the system. Then the observed event is compared with
synthetic light curves derived from trajectories in magnification maps. These
maps are generated using a ray-tracing technique. We take more than 10^9
trajectories and test a wide range of different physical properties of the
lensing galaxy and the source quasar (lens transverse velocity, microlens mass,
source intensity profile and source size). We found that around 75% of our good
trajectories (i.e. that are consistent with the observations) are caustic
crossings. In addition, a high transverse velocity exceeding 300 km/s, a
microlens mass of about 0.1 M_sun and a small standard accretion disk is the
best parameter combination. The results justify the interpretation of the
OGLE-GLITP event in Q2237+0305A as a caustic crossing. Moreover, the physical
properties of the lens and source are in very good agreement with previous
works. We also remark that a standard accretion disk is prefered to those
simpler approaches, and that the former should be used in subsequent
simulations.Comment: 5 pages, 3 figures, 3 tables, to appear in MNRA