Detection of the rapid variability in the Q2237+0305 quasar

TL;DR

This paper reports the first detection of rapid intrinsic variability in the quadruply lensed quasar Q2237+0305, enabling more precise estimates of its gravitational lensing time delays.

Contribution

It presents the first observation of short-term variability in Q2237+0305 and refines the time delay measurements using these new data.

Findings

Detected short-period variability of several days with 0.1-0.2 mag amplitude

Improved estimates of the gravitational lensing time delays

Confirmed the presence of microlensing effects in the light curves

Abstract

Rapid intrinsic variability has been detected for the first time in the Einstein Cross QSO 2237+0305, a radio quiet flat spectrum quasar at z=1.7 that is quadruply lensed by a foreground galaxy at z=0.04. The observed short-period event at the time scale of several days and with amplitudes of about 0.1-0.2 mag can be traced in the light curves of the 2004 observing season for all macroimages and in all the three filters (V, R and I). The accuracy of the existing estimates of the time delays in Q2237+0305 is insufficient to either confirm or disprove the estimations of time delays based on the lens models of this system, especially taking into account the presence of strong microlensing events. The detected short-period variations in the Q2237+0305 light curves have made it possible to obtain new estimates of the time delays, which are more accurate as compared to the earlier determinations by other authors.