A team of Spanish scientists, where the Universitat de València participates, measured accurately a structure in the innermost part of a quasar (very little far objects, that emit huge amounts of energy, just as much or even more than the whole galaxy that holds them) placed around 5,000 millions of light years from Earth.
It is about the most accurate measure achieved until now of such a small and far object, and the obtaining was possible due to the known gravitational microlensing effect, caused by the stars of a galaxy between the earth an the quasar that can magnify tiny regions inside the quasar.
In concrete, the researchers measured the internal border of the matter disk that orbits around the quasar Q2237+0305 (known as “The Einstein Cross”) through the study of the brightness of the different four images of the object, obtained thanks to the OGLE experiments (Optical Gravitational Lensing Experiment) and the GLITP (Gravitational Lensing International Time Project), that during 12 years and 9 months, respectively, were monitoring this quasar.
On the border of a black hole
When we observe a quasar in the optic, the energy comes from a matter disk in the form of a plasm that orbits at high speed around a supermassive black hole with a mass equivalent to the mass of billions of stars. The disk has a size comparable to our solar system, but it is so far that it is not possible to measure its structure with the traditional methods. In this case, this has been possible thanks to the gravitational lensing effect, that allowed to detect a structure in the internal border of the disk, on the border of the black hole.
In this work participated José Antonio Muñoz, professor of the Department of Astronomy and Astrophysics of the Universitat de València, researchers of the University of Granada, from the Astrophysics Institute of the Canary Islands and from the University of Cadiz. “During the last years we proved that microlensing allows to analyse the structure in quasars accretion disks and now we reached the innermost part of the disk, to a distance comparable to the distance of the nearest stable orbit to the black hole”, says the professor Muñoz.
As explained one of the authors of this work, the researcher of the Department of Theoretical Physics and Cosmos of the University of Granada Jorge Jiménez Vicente, “the great progress of this work was that we were able to detect, using the gravitational microlensing effect, a structure in the internal border of such a small disk, within such a great distance. It would be the equivalent, for example, to being able to detect a euro coin located at a distance of more than 100,000 kilometres”.
Only one out of each 500 quasars is affected by this gravitational lensing effect pehomena. The obtained information will be very useful for researchers in order to understand the quasars, that are essential to comprehend how galaxies formed and evolved.
Jiménez Vicente points that, in the future, when big monitoring programmes are available (such as the planned for the Large Synoptic Survey Telescope, a telescope of 8,4 metres able to examine the totality of the visible sky that will be build in the north of Chile and will become operational in 2022), “the possibility of detecting high magnification events produced by the microlensing effect will be extended to the detection of thousands of quasars”. And, therefore, “a unique window will be opened to explore the closest surroundings to supermassive black holes located in the centre of quasars”, concludes the researcher of the Universitat de València José Antonio Muñoz.
Bibliographic reference:
Resolving the Innermost Region of the Accretion Disk of the Lensed Quasar Q 2237+0305 through Gravitational Microlensing. E. Mediavilla, J. Jimenez-Vicente, J.A. Muñoz & T. Mediavilla, 2015, ApJL, 814, L26
Last update: 15 de december de 2015 11:47.
News release
