Prediction And Analysis Of Basic Gravitational Microlensing Phenomena
Creators: name: Nemiroff, Robert
Publisher: name: Zenodo
Year: 1987
Subjects: gravitational lensing, microlensing, photometery

description: The phenomena of gravitational microlensing are described, and predictions are made about its possible future detection. A mathematical formalism is developed which exploits gravitational lensing effects in terms of photometric measuring capability. This formalism is then used to outline the most probable places to look for microlensing.

Basic microlensing induced light curves are calculated for a variety of possible lens-source configurations. These configurations include that of a single star acting as a lens, and that of a double star acting as the lens. The light curve signatures of the double star lens are themselves indicators of the microlensing phenomenon. Light curve signatures for a single star acting on a uniform extended source are presented. Analysis is described listing methods by which parameters taken from this light curve could be used to recover both lens and source information.

The effect of microlensing on the shape of the spectral lines originating in the broad line region (BLR) of an active galactic nucleus (AGN) is analyzed. For various possible dynamical models of AGN make-up, it is shown that microlensing could distort the shape of a spectral emission line. Microlensing typically amplifies the center of the BLR emission line, but, for some models, in can amplify the wings, or shift the central peak instead.

A sample finding list of QSO's is presented for observers. For the assumption of galaxies made up entirely of compact objects, calculations are presented for each QSO on the list, listing optical depth for microlensing, the average time between microlensing events of various amplitudes, and the expected duration of an event. Possible observing programs are described.

Much could be learned from the identification and analysis of microlensing induced photometric and spectroscopic variations. Recoverable information includes AGN structure at 10-6 arcsecond resolution, galaxy proper motion at 10-6 arcsec/year, and the number of mass density of lensing stars in galaxies.
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