2008A&A...480..327A -
Astronomy and Astrophysics, volume 480, 327-334 (2008/3-3)
The multiple quasar Q2237+0305 under a microlensing caustic.
ANGUITA T., SCHMIDT R.W., TURNER E.L., WAMBSGANSS J., WEBSTER R.L., LOOMIS K.A., LONG D. and McMILLAN R.
Abstract (from CDS):
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 g'- and r'-band photometry at the Apache Point Observatory 3.5m telescope where we find that the event has a smaller amplitude in the r'-band than in the g'- and OGLE V-bands. By comparing the light curves with microlensing simulations we obtain constraints on the sizes of the quasar regions contributing to the g'- and r'-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 1.20x10
15sqrt(M/0.1M
☉)cm≲σ
g'≲7.96x10
15sqrt(M/0.1M
☉)cm, where M is the mean microlensing mass, and a ratio σ
r'/σ
g'=1.25
+0.45–0.15. With the limits on the velocity of the lensing galaxy from Gil-Merino et al. (
2005A&A...432...83G) as our only prior, we obtain 0.60x10
15sqrt(M/0.1 M
☉)cm≲σ
g'≲1.57x10
15sqrt(M/0.1M
☉)cm and a ratio σ
r'/σ
g'=1.45
+0.90–0.25 (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 ≥72 percent confidence.
Abstract Copyright:
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Journal keyword(s):
gravitational lensing - galaxies: quasars: individual: Q2237+0305 - cosmology: observations - accretion, accretion disks
CDS comments:
Fig. Standard star not identified.
Simbad objects:
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