Neutron star ‘glitch’ offers surprising look inside

A neutron star “glitch” is providing astronomers a peak at what happens within the mysterious objects.

The “glitch” happens when parts of the neutron star interior start to move outwards and the star begins to spin faster.

Researchers studied a neutron star known as the Vela Pulsar. Located in the southern sky, and approximately 1,000 light years from Earth, the Vela Pulsar is known to glitch about once every three years. Only 5% of pulsars glitch, so the Vela Pulsar’s regularity has made it a favorite of glitch hunters.

An artist's illustration shows the three neutron star components revealed during the 2016 Vela glitch.
Artist illustration of the three neutron star components revealed during the 2016 Vela glitch. (Credit: Carl Knox/OzGrav ARC Centre of Excellence for Gravitational Wave Discovery)

By reanalyzing data that coauthor Jim Palfreyman of the University of Tasmania obtained during the 2016 Vela glitch, the researchers found that the glitching star started spinning faster than previously observed, before relaxing down to a final state.

According to Paul Lasky of Monash University, this observation gives scientists the first-ever detailed glimpse into the interior of the star—revealing that the inside actually has three different components.

“One of these components, a soup of superfluid neutrons in the inner layer of the crust, moves outwards first and hits the rigid outer crust of the star, causing it to spin up,” says Lasky. “But then, a second soup of superfluid that moves in the core catches up to the first, causing the spin of the star to slow back down.”

Researchers, including coauthor Vanessa Graber from McGill University, have predicted this overshoot but had never been observed until now.

One glitching mystery, however, has led to another.

“Immediately before the glitch, we noticed that the star seems to slow down its rotation rate before spinning back up,” says first author Greg Ashton from the Monash School of Physics and Astronomy.

“We actually have no idea why this is, and it’s the first time it’s ever been seen! We speculate it’s related to the cause of the glitch, but we’re honestly not sure,” he says, adding that he suspects this new paper to spur some new theories on neutron stars and glitches.

The paper appears in the journal Nature Astronomy. Researchers from Monash University, the Australian Research Council’s Centre of Excellence for Gravitational Wave Discovery, McGill University, and the University of Tasmania contributed to the work.

Source: McGill University