Black Hole Chows Down As Scientists Watch
A growing black hole, called a quasar, can be seen at the center of a faraway galaxy in this artist's concept. Astronomers using NASA's Spitzer and Chandra space telescopes discovered swarms of similar quasars hiding in dusty galaxies in the distant universe.
Credit: NASA/JPL-Caltech

Scientists have watched matter falling into a black hole for the first time ever.

Explosively brilliant light produced from a black hole's gobbling of matter has reached telescopes through a fluke of physics called gravitational microlensing.

A transient phenomenon, gravitational microlensing is the curving of light around a star or galaxy due to the body's gravitational warping of space. In this case, the gravity acts like a lens that bends light from the distant black hole into a new focus for telescopes, temporarily magnifying the light source during an alignment of all the black hole, the massive object bending the light, and Earth.

Supermassive black holes like the one studied are about as wide as the distance from the Earth to the sun. At their immediate outskirts, swirling matter undergoes extreme compression and superheating, powering the hugely energetic displays of visible light known as a quasars.

"This technique can probe regions just a few times larger than the black hole at the center of a quasar in a matter of minutes, rather than decades," researcher David Floyd of the University of Melbourne in Australia told LiveScience.

Until now, light from quasars has only appeared as an infinitesimally small point, Floyd said. But the magnification offered by microlensing has allowed scientists to physically resolve the structure of the material falling into the black hole, obtaining information on ?exquisitely small scales? such as the light's colors, spectral lines, and direction.

Using data from the Magellan telescope in Chile and the NASA Hubble Space Telescope, scientists studied a quasar located in the constellation Hydra that dates from 9 billion years ago. In a statement, the researchers said they've discovered that 99 percent of its light originates in a region "just a thousand times larger than the black hole itself."

"This is so tiny in astronomical terms that it would take a telescope with a lens 100 kilometers [62 miles] across to observe directly," Floyd said.

Most of the ultraviolet light emitted by the quasar comes from a region 12 light-days across, "a little bit larger than our entire solar system," Floyd added.

Never before has the size of a quasar's shining region of gas been detected with such certainty. Also, the disk of spinning material around the black hole is much stiffer than previously expected.

"[The technique] allows us to examine how matter behaves in the vast gravitational fields around a black hole, and in particular, how it is able to shine in the most efficient manner in the universe," Floyd said.

Often outshining an entire galaxy, quasars are the most brilliant objects known. That's because black holes convert matter into radiation (think Einstein's E=mc2) in the most efficient way known, "at least a factor of ten more efficient than nuclear fusion," Floyd said.

The process by which they do this isn't fully understood, but is critical to the evolution of galaxies and the universe, Floyd said. Research opened up by the new technique will help scientists learn what kind of mechanism causes material to fall inward continuously even as ordinary forces keep it in a stable orbit like that of the Earth spinning around the sun.

Floyd presented his research this week at Fresh Science, a scientific festival at Australia's Melbourne Museum.