Reverberation of X-rays in the vicinity of a black hole
This animation depicts the environment in the vicinity of a black hole that is accreting matter via an accretion disc. Material in the disc spirals around the black hole and, heated by internal friction up to millions of degrees, radiates profusely at ultraviolet and soft X-ray wavelengths. Astronomers believe that a corona, populated by highly energetic electrons that shine brightly at hard X-ray wavelengths, is present above the disc. Further above the corona, part of the material from the disc is funnelled into a jet and ejected.
The animation shows how a sudden burst of light in the corona is translated into an increase in the emission from the accretion disc. As it propagates away from the corona, light emitted in the burst gradually illuminates the entire disc, inducing excitation in the disc material and causing it to shine in X-rays.
Observations performed with ESA's XMM-Newton X-ray observatory have revealed such 'reverberation' events occurring in the vicinity of the supermassive black hole hosted at the centre of the galaxy NGC 4151. By measuring the time delays between X-rays coming from the corona and from the disc, astronomers were able to map the vicinity of this black hole in unprecedented detail.