(Image credit: NASA/ESA/NSF’s NOIRLab/M. Garlick/M. Zamani)
Now that the mystery of FRBs (Fast Radio Bursts) has been largely explained, it’s satisfying to get a new Cosmic Mystery to wonder about.
This new one is called a Luminous Fast Blue Optical Transient (LFBOT). The first was observed in 2018 and new ones are observed at the rate of only about 1 per year. They are massive explosions but not typical of a supernova, being an order of magnitude or so brighter (in light, ultra violet, X-rays and radio waves but not gamma-rays) and lasting just a few days – whereas a supernova stays bright for weeks or months. Nor does the spectrum match a supernova – the latest was measured at 20,000 degrees Celsius – which is not as hot as some stars and way cooler than a supernova. The latest LFBOT was observed as not located in a galaxy – also surprising, and again mitigating against a supernova since a massive star ejected from the nearest galaxy would not live long enough to get to that observed position.
The two most likely theories are that either the LFBOT results from a star being ripped up by an intermediate-mass black hole, or that it results from a neutron star collision (kilonova) – unfortunately LIGO was not operating during the event so could not record any gravitational wave signature (thought it may have been too distant anyway).
Allan Brewer, Author: Blog on Cherry-picked Science 