Space scientists may have solved one of the universe’s greatest riddles – why black holes shine so brightly. The answer is magnetism, the same force that causes a hiker’s compass needle to swivel.
Black holes are the cannibals of the cosmos, gobbling up anything unlucky enough to come too close. Not even light can escape anything sucked inside. Now Nasa has found that gravity is not enough to explain why material gets pulled in. The black hole’s magnetic field plays a major role and also causes the doomed matter to flare like a distress beacon before it goes.
Black holes power the brightest objects in the universe, quasars, and shine with up to a quarter of the radiation emitted by the universe since the Big Bang. Nasa used a space telescope called Chandra, observing with X-ray eyes, to study a black hole called J1655 in our own galactic back yard. The black hole is stripping gas from a close-by star and swallowing it up.
Nasa’s results show that gravity is not enough to pull the material in. Instead the data confirmed that magnetic turbulence helps drive gas into the black hole and also generates the light that shines outwards and turns them into celestial beacons.
The discovery team, led by Jon Miller, of Michigan University, announce their findings in the journal Nature. Miller says: “By intergalactic standards J1655 is in our backyard, so we can use it as a scale model to understand how all black holes work, including the monsters found in quasars.”
The major discovery will help astronomers to understand how black holes grow. They will also try to learn how magnetic fields affect disks of material detected around young sun-like stars where planets are forming.
The Earth has a magnetic field which helps cause spectacular auroras when it is buffeted by electrically charged particles from the Sun called the solar wind.
The artist’s impression shows gas being stripped from a star by a black hole together with an X-ray spectrum measured by Chandra.