Within just 10 days, this extraordinary explosion shines more than 100 billion times brighter than the sun before disappearing almost entirely. It’s a brief yet more spectacular event than a typical supernova.
Illustration of a black hole tearing apart a nearby star. Researchers believe such a collision could be the cause of this new type of explosion. (Image: ESA/C. Carreau)
According to research published on September 1st in the Astrophysical Journal, this rapid and intense event may represent a previously unstudied type of cosmic explosion.
The lead author of the study, Matt Nicholl, an astrophysicist at Queen’s University Belfast, stated: “We’ve named this new source ‘Fast Blue Optical Transient’ or FBT. The detailed data we’ve gathered rules out the possibility of it being another type of supernova.”
Supernovae are bright explosions that occur when massive stars (usually at least 8 times the mass of the sun) burn through their nuclear fuel, collapse, and eject their outer gas layers into space.
Each year, astronomers observe hundreds of supernovae suddenly brightening and then gradually fading. Typically, a supernova reaches peak brightness in about 20 days, shining billions of times brighter than the sun. Over the following months, the explosion slowly disappears. However, the FBT is not a supernova.
The newfound explosion, discovered by astronomers using the Asteroid Terrestrial-impact Last Alert System (ATLAS) telescope network in Hawaii, Chile, and South Africa, occurred in a galaxy filled with sun-like stars too small to produce the materials for a supernova.
Co-author Shubham Srivastav, a researcher at Queen’s University, said, “Our data indicates that this event took place in a giant red galaxy located about two billion light-years away. These galaxies contain billions of sun-like stars, but none of them are massive enough to become supernovae.”
According to the researchers, in addition to its unusual location, the newly discovered explosion was much brighter and faded much faster than a typical supernova. Over the next 15 days, this object dimmed by two orders of magnitude and was only 1% as bright as at its peak, just one month after the explosion.
The research team concluded that these explosions represent a new type of cosmic explosion – rare and likely unrelated to dying stars. So, what exactly is the FBT? At present, the research team can only speculate. Nicholl suggests, “The most plausible explanation seems to be a black hole colliding with a star.”
However, even this explanation is not entirely fitting. It’s possible that scientific models of star-black hole collisions need refinement, or astronomers may not yet have enough information about FBT to draw any conclusions. The team will continue to search for more of these enigmatic explosions in galaxies closer to Earth.