A cosmic event far away unleashed more energy in half a second than the Sun will produce in its entire lifetime. Researchers from Northwestern University suggest this gamma-ray burst marks the birth of a magnetar from two merging neutron stars—a potential first in astronomical observations.
When massive stars exhaust their fuel, they expel their outer layers and collapse under gravity, forming incredibly dense neutron stars: objects just kilometers across, packing a billion tons per cubic meter, bound by gravity and composed mostly of neutrons.
Some neutron stars spin rapidly, emitting intense radiation beams that appear as pulsing signals from Earth when aligned with our view—like cosmic lighthouses known as pulsars.
Others boast extraordinarily powerful magnetic fields, earning them the name magnetars.
Months ago, astronomers at Northwestern University, using NASA's Neil Gehrels Swift Observatory, spotted an intense flare in a distant galaxy. They mobilized telescopes for multi-wavelength observations—in optical, X-ray, near-infrared, and radio—revealing the brightest short gamma-ray burst on record. Yet something stood out.
The near-infrared emission, captured by Hubble, was ten times brighter than expected compared to X-ray and radio data. "This prompted us to challenge conventional models and consider a novel phenomenon," says lead researcher Wen-fai Fong.
Short gamma-ray bursts like this are typically produced by neutron star mergers. Most result in a hypermassive neutron star that collapses into a black hole almost instantly. But here, the merged remnant may have endured as a magnetar.
"Our analysis indicates this heavy object survived, forming a rapidly spinning, highly magnetized neutron star that powered an exceptionally bright afterglow," explains Fong.
"We observe magnetars in our Milky Way, usually born from massive star explosions. But a fraction could arise from neutron star mergers," she adds.
Confirmation awaits: if magnetar-born, the ejected material should emit light at radio wavelengths within years. Future observations will verify this groundbreaking possibility.
