Washington, Nov 4 (ANI): An international team of astronomers have used the NASA/ESA Hubble Space telescope to study the bright disc of matter surrounding the black hole.
Combining the telescope with the gravitational lensing effect of stars in a distant galaxy, the team measured the disc's size and studied the colours and temperatures of different parts of the disc.
The team observed a group of distant quasars that are gravitationally lensed by the chance alignment of other galaxies in the foreground, producing several images of the quasar, and spotted subtle differences in colour between the images, and changes in colour over the time.
Quasars, short for quasi-stellar objects, are glowing discs of matter that orbit supermassive black holes, heating up and emitting extremely bright radiation as they do so.
By recording the variation in colour, the team were able to reconstruct the colour profile across the accretion disc, which is important because the temperature of an accretion disc increases the closer it is to the black hole, and the colours emitted by the hot matter get bluer the hotter they are.
The team measured the diameter of the disc of hot matter, and plotted how hot it is at different distances from the centre, and found that the disc is between four and eleven light-days across (approximately 100 to 300 billion kilometres).
"This result is very relevant because it implies we are now able to obtain observational data on the structure of these systems, rather than relying on theory alone," Jose Munoz, the lead scientist in this study, said.
"Quasars'' physical properties are not yet well understood. This new ability to obtain observational measurements is therefore opening a new window to help understand the nature of these objects," he added.
The study will appear in the December issue of the Astrophysical Journal. (ANI)
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