The physics behind some of the most extraordinary stellar objects in the Universe just became even more puzzling. A group of astronomers led by McGill researchers using NASA’s Swift satellite have discovered a new kind of glitch in the cosmos, specifically in the rotation of a neutron star.
Neutron stars are among the densest objects in the observable universe; higher densities are found only in their close cousins, black holes. A typical neutron star packs as much mass as half-a-million Earths within a diameter of only about 20 kilometers. A teaspoonful of neutron star matter would weigh approximately 1 billion tons, roughly the same as 100 skyscrapers made of solid lead.
Neutron stars are known to rotate very rapidly, from a few revolutions per minute to as fast as several hundred times per second. A neutron star glitch is an event in which the star suddenly begins rotating faster. These sudden spin-up glitches have long been thought to demonstrate that these exotic ultra-dense stellar objects contain some form of liquid, likely a superfluid.
This new cosmic glitch was detected in a special kind of neutron star — a magnetar — an ultra-magnetized neutron star that can exhibit dramatic outbursts of X-rays, sometimes so strong they can affect Earth’s atmosphere from clear across the galaxy. A magnetar’s magnetic field is so strong that, if one were located at the distance of the Moon, it could wipe clean a credit card magnetic strip here on Earth.
Now astronomers led by a research group at McGill University have discovered a new phenomenon: they observed a magnetar suddenly rotate slower — a cosmic braking act they’ve dubbed an “anti-glitch.” The result is reported in the May 30 issue of Nature.
The magnetar in question, 1E 2259+586 located roughly 10,000 light years away in the constellation of Cassiopeia, was being monitored by the McGill group using the Swift X-ray telescope in order to study the star’s rotation and try to detect the occasional giant X-ray explosions that are often seen from magnetars.
“I looked at the data and was shocked — the neutron star had suddenly slowed down,” says Rob Archibald, lead author and MSc student at McGill University. “These stars are not supposed to behave this way.” Via Cosmic glitch: Astronomers discover new phenomenon in neutron star.