The kilonova story
A pair of neutron stars that merged over a billion light years away could have created an unexpected cosmic relative of a past gravitational wave
Two neutron stars collided and we weren't expecting the result
The universe is full of enormous cosmic events that produce vast amounts of energy and elements that are spread throughout the cosmos. Some of these take millions of years, for example observing a star slowly deplete its fuel before exploding, resulting in a supernova. On the other hand, some take place in a fraction of a second, like the merging of neutron stars that creates gravitational waves. The latter are an enigma to astronomers, and our understanding of them has only evolved significantly in the last year or so with the Laser Interferometer Gravitational-Wave Observatory, or LIGO as it’s more commonly known, in the United States and the Virgo interferometer in Italy.
Just recently, astronomers found a peculiar signal that they believe to be from two colliding neutron stars. This event was originally spotted as a rapid emission of light in the gamma-ray section of the electromagnetic spectrum, giving it the name GRB – an abbreviation for gamma-ray burst – 150101B. This rapid burst of light was first spotted by the Gamma-ray Burst Monitor aboard NASA’s Fermi Space Telescope on 1 January 2015. Followup observations were made using a whole host of telescopes over a series of wavelengths, including NASA’s Neil Gehrels Swift Observatory and Chandra X-ray Observatory, both in space, and the 6.5-metre (21-foot) Magellan Telescope at the Las Campanas Observatory in Chile.
“GRB150101B was discovered by NASA's Fermi mission, but its position in the sky was not known very well and we could not perform any other observations because we did not know where to look,” Dr Eleonora Troja from NASA’s Goddard Space Flight Center in Greenbelt, Maryland, United