Scientists analyzing an X-ray image of the universe detected a large but unexplained explosion that occurred from a galaxy located about 10.7 billion light-years away in a region called the Chandra Deep Field-South.
From Faint To Super Bright
NASA's Chandra X-ray Observatory, which has been monitoring the galaxy over the past 17 years, has not detected a similar event before. The galaxy was initially relatively faint but in October 2014, it became a thousand times brighter over a span of a few hours, before getting back into its old state again. Scientists cannot attribute this behavior with certainty to any known astronomical phenomenon.
The explosion was observed to be very powerful that the X-ray source generated a thousand times more energy than all the galaxy's stars in just a matter of minutes. Researchers said that they have not yet detected any similar event anywhere in the universe.
Kevin Schawinski, a researcher from ETH Zurich in Switzerland, said that what they have observed could be a completely new type of cataclysmic event. He said that more observations are needed to know what they saw.
Hypotheses
Although the nature of the explosion is still to be unveiled, researchers have proposed several hypotheses that may provide an explanation for the explosion. Two of the three main hypotheses involved gamma-ray bursts, or GRBs.
GRBs are the brightest electromagnetic events scientists have so far identified in the universe. Scientists think that these highly energetic explosions are released when a massive star collapses on itself, or when a black hole and a neutron star, or two neutron stars, merge.
"Lasting anywhere from a few milliseconds to several minutes, GRBs shine hundreds of times brighter than a typical supernova and about a million trillion times as bright as the Sun," NASA explains. "When a GRB erupts, it is briefly the brightest source of cosmic gamma-ray photons in the observable Universe."
When GRBs point toward Earth as they happen, astronomers can detect the bombarding jet of gamma-rays before this tapers and the Earth is flooded with the weaker radiation. It is possible that the mysterious X-ray explosion could be of a GRB that is not pointed to Earth so it looks new. It is also potentially an evidence of a GRB that occurs beyond the galaxy.
The other potential reason for the explosion could be that of a black hole shredding a white dwarf in the distant galaxy. Researchers, however, said that none of these ideas perfectly fit the data of the phenomenon.
"None of the above scenarios can completely explain all observed properties," study researcher Ezequiel Treister, from Chile's Pontifical Catholic University, and colleagues wrote in their study, set to be published in the Monthly Notices of the Royal Astronomical Society in June.
"Although large uncertainties exist, the implied rate of such events is comparable to those of orphan and low-luminosity GRBs as well as rare TDEs, implying the discovery of an untapped regime for a known transient class, or a new type of variable phenomena whose nature remains to be determined."
