Washington D.C.: A team of scientists has accurately detected a structure in the innermost region of a quasar at a distance of more than five billion light-years from Earth.
It's the most accurate measure achieved until now of such a small and distant object, and it has been achieved thanks to the so-called gravitational microlensing effect, caused by stars belonging to a galaxy between us and the quasar, and which may magnify tiny regions within the quasar.
In particular, the Spanish researchers, with the participation of the University of Granada (UGR), have managed to measure the inner edge of the disk of matter (accretion disk) orbiting around the quasar Q2237+0305 (known as "Einstein Cross") through the study of the changes in the brightness of four different images of said quasar.
Said images were obtained thanks to the OGLE (Optical Gravitational Lensing Experiment) and GLITP (Gravitational Lensing International Time Project) experiments, which monitored that quasar for 12 years and for 9 months, respectively.
Researcher Jorge Jimenez Vicente explained that the breakthrough of this work has been that they have been able to detect a structure in the inner edge of such a small disk at such a great distance, thanks to the gravitational microlensing effect. It would be the equivalent to detecting a Euro coin at a distance of more than 100000 kilometers.
Jimenez Vicente notes that, in the future, when great monitoring programs are available, "the possibility of detecting high magnification events caused by the gravitational microlensing effect could be applied to thousands of quasars."
The study appears in Astrophysical Journal Letters.