Gravitational Microlensing of Quasar Clouds : Detectability in a Worst-Case Scenario

Abstract

It is believed that the Broad Emission Line Region of Quasars consists of discrete clouds. Due to the suspected small size of a cloud, the radiation from clouds may be strongly amplified by gravitational microlensing. It is shown that under some conditions, it is possible to detect gravitational microlensing even in a situation where the position and the velocity of clouds are non-correlated. Recommendations are made with respect to planning of observations, based on whether one has knowledge as to the number of clouds or not. If one knows that there are approximately 1 million clouds, there is good chance to detect lensing. If one has no knowledge of the number of clouds, one should choose instruments and objects that can provide the strongest lines and resolve it into as many as 1000 bins. Linear regression is used to derive relations that can be used for prediction of conditions where lensing can be detected.