Separating Intrinsic And Microlensing Variability Using Parallax Measurements

Abstract

In gravitational lens systems with 3 or more resolved images of a quasar, the intrinsic variability may be unambiguously separated from the microlensing variability through parallax measurements from 3 observers when there is no relative motion of the lens masses (Refsdal 1993). In systems with fewer than 3 resolved images, however, this separation is not straightforward. For the purpose of illustration, I make the following simplifications for the one-dimensional case: The observations consist of well-sampled time series of the observed flux FA(ti) and FB(ti) at two points in the observer plane. The separation vector of the two points is parallel to the direction of the transverse motion of the source-lens-observer system, and the distance DAB between the observers is known. Furthermore, the distance DAB is small compared to the typical length scale of fluctuations in the magnification μ(x).