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Title: Microlensing as a possible probe of event-horizon structure in quasars

In quasars which are lensed by galaxies, the point-like images sometimes show sharp and uncorrelated brightness variations (microlensing). These brightness changes are associated with the innermost region of the quasar passing through a complicated pattern of caustics produced by the stars in the lensing galaxy. In this paper, we study whether the universal properties of optical caustics could enable extraction of shape information about the central engine of quasars. We present a toy model with a crescent-shaped source crossing a fold caustic. The silhouette of a black hole over an accretion disk tends to produce roughly crescent sources. When a crescent-shaped source crosses a fold caustic, the resulting light curve is noticeably different from the case of a circular luminosity profile or Gaussian source. Furthermore, with good enough monitoring data, the crescent parameters, apart from one degeneracy, can be recovered.
Authors:
 [1] ;  [2] ;  [1] ;  [1] ;  [3]
  1. Univ. of Zurich, Zurich (Switzerland)
  2. Univ. of Zurich, Zurich (Switzerland); Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
  3. Univ. of Zurich, Zurich (Switzerland); SwitzerlandZentrum fur Astronomie der Univ. Heidelberg, Heidelberg (Germany)
Publication Date:
Report Number(s):
arXiv:1604.01769; FERMILAB-PUB-16-724-A
Journal ID: ISSN 0035-8711; 1444474
Grant/Contract Number:
AC02-07CH11359
Type:
Accepted Manuscript
Journal Name:
Monthly Notices of the Royal Astronomical Society
Additional Journal Information:
Journal Volume: 475; Journal Issue: 2; Journal ID: ISSN 0035-8711
Publisher:
Royal Astronomical Society
Research Org:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; gravitational lensing: micro; methods: numerical
OSTI Identifier:
1408334

Tomozeiu, Mihai, Mohammed, Irshad, Rabold, Manuel, Saha, Prasenjit, and Wambsganss, Joachim. Microlensing as a possible probe of event-horizon structure in quasars. United States: N. p., Web. doi:10.1093/mnras/stx3166.
Tomozeiu, Mihai, Mohammed, Irshad, Rabold, Manuel, Saha, Prasenjit, & Wambsganss, Joachim. Microlensing as a possible probe of event-horizon structure in quasars. United States. doi:10.1093/mnras/stx3166.
Tomozeiu, Mihai, Mohammed, Irshad, Rabold, Manuel, Saha, Prasenjit, and Wambsganss, Joachim. 2017. "Microlensing as a possible probe of event-horizon structure in quasars". United States. doi:10.1093/mnras/stx3166. https://www.osti.gov/servlets/purl/1408334.
@article{osti_1408334,
title = {Microlensing as a possible probe of event-horizon structure in quasars},
author = {Tomozeiu, Mihai and Mohammed, Irshad and Rabold, Manuel and Saha, Prasenjit and Wambsganss, Joachim},
abstractNote = {In quasars which are lensed by galaxies, the point-like images sometimes show sharp and uncorrelated brightness variations (microlensing). These brightness changes are associated with the innermost region of the quasar passing through a complicated pattern of caustics produced by the stars in the lensing galaxy. In this paper, we study whether the universal properties of optical caustics could enable extraction of shape information about the central engine of quasars. We present a toy model with a crescent-shaped source crossing a fold caustic. The silhouette of a black hole over an accretion disk tends to produce roughly crescent sources. When a crescent-shaped source crosses a fold caustic, the resulting light curve is noticeably different from the case of a circular luminosity profile or Gaussian source. Furthermore, with good enough monitoring data, the crescent parameters, apart from one degeneracy, can be recovered.},
doi = {10.1093/mnras/stx3166},
journal = {Monthly Notices of the Royal Astronomical Society},
number = 2,
volume = 475,
place = {United States},
year = {2017},
month = {12}
}