The time delays in gravitationally lensed quasars

Estimation of time delays is necessary for many applications in astrophysics and cosmology, such as the determination of the Hubble constant, the study of matter distribution at different spatial scales in the Universe, including the dark matter, and others. Estimation of the Hubble constant from the time delays requires them to be measured with a rather high accuracy — of the order of 1 percent. However, the accuracy of the available measurements is as a rule much lower. One of the most serious complications in time delay determination is due to microlensing events, which distort the intrinsic quasar light curves differently in different quasar images. The method that provides a simple way to mitigate the effects of microlensing for the case of so-called slow microlensing events is proposed. The method can be efficient in processing and analyzing of the large observational data flows.