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Astron. Astrophys. 340, L23-L26 (1998)

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Letter to the Editor

Caustic crossings in quasar light curves?

M.R.S. Hawkins

Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK

Received 5 August 1998 / Accepted 21 October 1998

Abstract

Numerical simulations and theoretical studies of the gravitational microlensing effect of a population of small bodies distributed along the line of sight to a compact light source such as a quasar indicate that caustic crossing effects will be present given a sufficiently large optical depth to lensing. These events will produce characteristic patterns in the quasar light curve. In this paper we use a large sample of quasar light curves to search for features with the properties of caustic crossing events. Two good candidates are presented which it is argued are not easily explained as intrinsic variation of the quasars. The relation between these events and microlensing features seen in multiple quasar systems are discussed, as well as the implications for the dark matter problem of a population of microlensing bodies.

Key words: galaxies: quasars: general – dark matter – gravitational lensing

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© European Southern Observatory (ESO) 1998

Online publication: November 9, 1998
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