A mysterious flash of X-rays captured in the deepest X-ray image ever taken has baffled astronomers.
The ultra-bright burst is believed to have originated from a small galaxy about 10.7 billion light years from Earth.
But little else is known about the source, which erupted in brightness by a factor of 1,000 for just a few hours last October.
“Ever since discovering this source, we’ve been struggling to understand its origin,” said Franz Bauer of the Pontifical Catholic University of Chile in Santiago, Chile. “It’s like we have a jigsaw puzzle but we don’t have all of the pieces.”
One of the possible explanations is that the flash was caused by a gamma-ray burst event.
GRBs occur when a massive star collapses, two neutrons merge or a neutron star merges with a black hole.
They send jetted explosions across the cosmos and, as they expand, lose energy, producing weaker radiation, such as X-rays.
The second possible origin is a medium-sized black hole that has been shredded by a white dwarf star.
“None of these ideas fits the data perfectly,” said co-author Ezequiel Treister, also of the Pontifical Catholic University, “but then again, we’ve rarely if ever seen any of the proposed possibilities in actual data, so we don’t understand them well at all.”
The third possibility is that astronomers might have come across an entirely new kind of explosion.
“We may have observed a completely new type of cataclysmic event,” said co-author Kevin Schawinski, of ETH Zurich in Switzerland. “Whatever it is, a lot more observations are needed to work out what we’re seeing.”