Bibcode
Mediavilla, E.; Jiménez-vicente, J.; Muñoz, J. A.; Mediavilla, T.
Referencia bibliográfica
The Astrophysical Journal Letters, Volume 814, Issue 2, article id. L26, 5 pp. (2015).
Fecha de publicación:
12
2015
Número de citas
15
Número de citas referidas
14
Descripción
We study three high magnification microlensing events, generally
recognized as probable caustic crossings, in the optical light curves of
the multiply imaged quasar Q2237+0305. We model the light curve of each
event as the convolution of a standard thin disk luminosity profile with
a straight fold caustic. We also allow for a linear gradient that can
account for an additional varying background effect of microlensing.
This model not only matches noticeably well the global shape of each of
the three independent microlensing events but also gives remarkably
similar estimates for the disk size parameter. The measured average
half-light radius, {R}1/2=(3.0+/- 1.5)\sqrt{M/0.3Mȯ }
light-days, agrees with previous estimates. In the three events, the
core of the magnification profile exhibits “fine structure”
related to the innermost region of the accretion disk (located at a
radial distance of 2.7 ± 1.4 Schwarzschild radii according to our
measurement). Relativistic beaming at the internal rim of the accretion
disk can explain the shape and size of the fine structure, although
alternative explanations are also possible. This is the first direct
measurement of the size of a structure, likely the innermost stable
circular orbit, at ∼3 Schwarzschild radii in a quasar accretion
disk. The monitoring of thousands of lensed quasars with future
telescopes will allow the study of the event horizon environment of
black holes in hundreds of quasars in a wide range of redshifts (0.5
< z < 5).
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Evencio
Mediavilla Gradolph