NASA's Hubble Space Telescope has spotted a flash of light 10 times brighter than expected... but what is it? It could be the birth of a so-called magnetar (a neutron star with dense magnetic fields).
When two neutron stars collide, the universe screams. The extreme collision is explosive and creates a “kilonova,” which emits a bright, rapid burst of gamma rays. It also sends ripples through the fabric of space-time. Scientists then believe that the cosmic “snapping” likely creates a new merged object that quickly collapses into a black hole. But… what if it survives?
A new study, to be published in The Astrophysical Journal, describes the brightest kilonova yet and suggests that a collision can sometimes cause the creation of a magnetar, a neutron star with dense magnetic fields.
On May 22, NASA's Neil Gehrels Space Telescope detected a gamma-ray burst in an extremely distant corner of space, dubbed GRB 200522A. Scientists believe these types of small bursts occur when two neutron stars collide, so when a telescope sees one, there's a frantic effort to get observations at other wavelengths in the electromagnetic spectrum. The collision in question happened about 5.5 billion years ago, but our telescopes are now picking up the signals.
In the new study, the research team pointed a number of different space and ground-based telescopes at GRB 200522A, including NASA's Hubble Space Telescope, and observed the falloff after the intense gamma-ray burst.
Using X-ray, radio, and infrared data, the team was able to measure the brightness of the gamma-ray burst. However, there was one particular observation that wasn't very normal. Near-infrared images from Hubble showed an extremely bright burst —about 10 times brighter than any kilonova ever seen (though few have been observed so far).
“The infrared light we saw from GRB 200522A was too bright to be explained by a typical radioactive kilonova,” says Wen-fai Fong, an astrophysicist at Northwestern University and lead author of the new research.
Fong and her team eventually settled on a model they called a “magnetar-boosted kilonova” to explain the extreme brightness.
Kilonovas are created when two dense cosmic objects – such as neutron stars and black holes – collide with each other. The merger process hurls a ton of subatomic material into space, including creating a gamma-ray burst.
Continuous monitoring of GRB 200522A with radio telescopes will help experts more clearly determine what exactly happened around the gamma-ray burst. Radio waves from the event should be able to confirm what was observed in infrared, but the time it takes for those waves to reach Earth depends on the environment around GRB 200522A. The model suggests it could take about six years before we get such a signal , and Fong says the team will monitor the radio emissions for years to come.
