We use the high magnification event seen in the 1999 OGLE campaign light curve of image C of the quadruply imaged gravitational lens Q2237+0305 to study the structure of the quasar engine. We have obtained - and -band photometry at the Apache Point Observatory 3.5 m telescope where we find that the event has a smaller amplitude in the -band than in the - and OGLE -bands. By comparing the light curves with microlensing simulations we obtain constraints on the sizes of the quasar regions contributing to the - and -band flux. Assuming that most of the surface mass density in the central kiloparsec of the lensing galaxy is due to stars and by modeling the source with a Gaussian profile, we obtain for the Gaussian width 1.20 × 1015 cm √M/0.1 M⊙ cm ≤ σd ≤ 7.96 × 1015 √M/0.1 M⊙ cm, where is the mean microlensing mass, and a ratio σr'/σd = 1.25+0.45-0.15 With the limits on the velocity of the lensing galaxy from Gil-Merino et al. (2005) as our only prior, we obtain 0.60 × 10 15 cm √M/0.1 M⊙ cm ≤ σd ≤ 7.96 × 10 15 √M/0.1 M⊙ cm cm and a ratio (all values at 68 percent confidence). Additionally, from our microlensing simulations we find that, during the chromatic microlensing event observed, the continuum emitting region of the quasar crossed a caustic at percent confidence.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science
- Accretion, accretion disks
- Cosmology: observations
- Galaxies: quasars: individual: Q2237+0305
- Gravitational lensing