Feb 28 2020
Astronomers Detect Largest Explosion Ever
We can quibble about whether or not the Big Bang should be considered an explosion, or whether it happened “in the universe.” It was the expansion of spacetime that is the universe. In any case, astronomers have detected what they think is the biggest explosion (at least discovered so far) since the big bang – in the Ophiuchus galaxy cluster, 390 million light years from us. The explosion is essentially a bubble with a diameter the size of 15 Milky Way galaxies – about 1.5 million light years across. That’s five time bigger than the previous record holder.
Astronomers first suspected something was going on when they discovered a big X-ray bubble. They report:
It was discovered in the Chandra X-ray image by Werner and collaborators, who considered a possibility of it being a boundary of an AGN-inflated bubble located outside the core, but discounted this possibility because it required much too powerful an AGN outburst.
An AGN is an active galactic nuclei – more on that below. So they initially discounted it because it was too big, but they then followed up with radio observation, and found an identical radio bubble, confirming that this was a real fossil of an ancient explosion, centered around an AGN. So what’s going on here?
Well, astronomers are not sure. The do not know exactly what may have caused some a massively energetic event. But let’s give some background on AGNs – these are supermassive black holes (SMBH) in the centers of galaxies. Most galaxies have them, including our own. But some supermassive black holes are more super massive than others – getting up to billions of solar masses. More importantly to their activity, some of the black holes are feeding, which means that gas and dust are actively swirling around the event horizon forming an accretion disc and then plunging into the incredible gravity well of the black hole. All that gravity represents an unimaginable amount of energy, and when that gas and dust falls in it swirls around at relativistic speeds – near the speed of light.