The galaxy we call home has a gigantic ‘supermassive’ black hole at its centre which has so far failed to swallow up Earth and all its beautiful residents. Now Nasa thinks it knows why the dark behemoth is relatively quiet compared to its greedy cousins in other galaxies. The hole is called Sagittarius A* and is lurking about 25,640 light years away from Earth – which is great because this means it’s more or less certain to never eat our planet. New research from Nasa has explained why the cosmic colossus does not appear to be as ravenous as more ‘active’ black holes, which feast on anything nearby and then emit huge burps of high energy radiation.
Astronomers used the Stratospheric Observatory for Infrared Astronomy (SOFIA) to examine the magnetic fields around Sagittarius A*. They found that the field ‘channels’ the gas surrounding the hole into orbit around it.
If magnetic forces steered the gas into the monster, it would become ‘active’. ‘The spiral shape of the magnetic field channels the gas into an orbit around the black hole,’ said Darren Dowell, a scientist at NASA’s Jet Propulsion Laboratory. ‘This could explain why our black hole is quiet while others are active.’ Scientists recently discovered that the supermassive monster blasting a beam of radio waves directly at our planet. But don’t worry, because although scientists really have spotted this ‘jet’ emanating from the behemoth, it doesn’t mean we’re about to get blasted into oblivion due to the gigantic distance between Earth and Sagittarius A*.
It’s surrounded by a foggy cloud of hot gas, meaning we can’t just snap pictures of it using traditional telescopes. And it’s so far away that looking at it is like trying to spot a tennis ball on the moon from down here on Earth. Now scientists from Radboud University in The Netherlands have used a technique called Very Long Baseline Interferometry which combines several different telescopes on Earth to form one massive ‘virtual telescope’.
They found that a beam of radio waves is blasting towards Earth, which sounds ominous but probably just means the black hole is lying on its side.
It may also mean the radio waves are being produced inside a cloud of gas that’s being sucked into the hole, although this would be highly unusual. ‘This may indicate that the radio emission is produced in a disk of infalling gas rather than by a radio jet,” explained PhD student Sara Issaoun. ‘However, that would make Sgr A* an exception compared to other radio emitting black holes. The alternative could be that the radio jet is pointing almost at us.’
SOURCE: METRO
No comments:
Post a Comment