Astronomers take the measure of a quasar's inner sanctum
Using the Hubble Space Telescope, astronomers have captured light from the disk of dust and gas surrounding a supermassive black hole at the heart of a quasar.
Chandra X-ray Observatory Center/Reuters
For decades, powerful cosmic beacons known as quasars have defied efforts to measure the physical structure of features thought to be driving the brilliant beams of light and other types of radiation quasars produce.
Now, astronomers using the Hubble Space Telescope – with a lot of help from stars in an intervening galaxy – have captured light from the disk of dust and gas feeding a supermassive black hole at the heart of a quasar. Clues embedded in the light have allowed them to estimate the size of the accretion disk and provide a crude map of the disk's temperature differences.
Quasars are large galaxies with cores that emit vast amounts of radiation as material approaches their central black holes and heat to enormous temperatures before vanishing. The supermassive black holes themselves are millions to billions of times more massive than the sun.
The quasar in question is some 10.8 billion light-years away. The disk, the team calculates, extends up to seven light-days – or about 1,300 astronomical units – from the central black hole. One astronomical unit spans the distance between Earth and the sun.
The detection is a bit like spotting a single grain of moon dust from Earth, according to the team conducting the study.