Hubble sees round corners to image distant black holes

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An international team of astronomers has used the Hubble Space Telescope to observe the accretion disc - the brightly glowing disc of matter, or quasar - around a supermassive black hole at the centre of a distant galaxy.

It's a remarkable image that has allowed scientists to measure the quasar's size with phenomenal accuracy, and even plot the temperature gradient across it. But what's really special about the picture is the way it was compiled.

The team used an amazing novel technique that takes advantage of the light bending and focusing power of gravitational lensing to see past an intervening galaxy to the even more remote quasar.

As the stars in the intervening galaxy move in front of the quasar, gravitational effects distort and amplify its light. Subtle changes in the strength and colour of that light as the galaxy transits across can then be pieced together to reveal the structure of the distant quasar.

The technique gives an immense boost to the power of the telescope - equivalent to spotting individual grains of sand on the surface of the moon.

This video shows how the team, lead by Jose Munoz at the University of Valencia, came up with the image of quasar HE 1104-1805, one of the brightest yet discovered.

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