Gravitational waves — hypothesized for 100 years but eluding our best efforts to actually find them — were finally detected in February. Those waves were produced by a pair of black holes that collided more than a billion years ago and created enough of a disturbance that the faint signals caused a ripple in space time. It was a bombshell finding that gives us hope we can finally understand a dimension of the universe we’ve been blind to up ‘til now.
And now, NASA scientists are finding out there was quite bit more emanating from that black hole than just gravitational waves. A half second after the gravity waves were picked up by the Laser Interferometer Gravitational-Wave Observatory (LIGO) interferometers, NASA’s Fermi Gamma-ray Space Telescope found a different signal: gamma rays.
In a new paper being reviewed by The Astrophysical Journal, scientists from the Gamma-ray Burst Monitor (GMB) say new analysis shows only a 0.2 percent chance that the gravity waves and gamma rays were measured like this in close proximity as a coincidence.
And this is important, because if they truly are not coincidental, the presence of gamma rays from a black hole merger illustrates that they merge “cleanly” — without producing light.
“This is a tantalizing discovery with a low chance of being a false alarm,” Valerie Connaughton, a GMB team member at NASA and the lead author of the paper, said in a news release.
The Fermi telescope is specifically designed to look for x-rays and gamma rays protruding through space. Most of what they find is light and energy coming from short gamma-ray bursts, which last less than two seconds and are thought to be made from crashes between neutron stars and black holes. These same objects are also the primary culprits for producing gravitational waves.
The new study suggests the relationship between the two types of signals is closer than we thought. Among several things, this means it might prove useful to use gamma rays in some capacity to find gravitational waves themselves.
“A GBM detection allows us to whittle down the LIGO area and substantially shrinks the haystack,” said GBM team member Eric Burns.
Scientist are trying everything right now to help narrow the search for gravitational waves down from what is currently all of space. Fermi could prove to be a valuable tool in narrowing down where we want to look for gravitational waves.
We’ll have to wait a bit longer until the final version of the paper is published before scientists decide how they want to use this information, but suffice to say, there will be a vibrant discussion to be had.