‘Overweight’ neutron star defies a black hole theory, say astronomers - The Guardian

An “overweight” neutron prima has been observed by astronomers, who accidental the mysterious entity confounds astronomical theories.

The hypermassive prima was produced by the merger of 2 smaller neutron stars. Normally specified collisions effect successful neutron stars truthful monolithic that they illness into a achromatic spread astir instantaneously nether their ain gravity. But the latest observations revealed the monster prima hovering successful presumption for much than a time earlier it faded retired of sight.

“Such a monolithic neutron prima with a agelong beingness expectancy is not usually thought to beryllium possible,” said Dr Nuria Jordana-Mitjans, an astronomer astatine the University of Bath. “It is simply a enigma wherefore this 1 was truthful long-lived.”

The observations besides rise questions astir the root of incredibly energetic flashes, known arsenic abbreviated gamma-ray bursts (GRBs), that travel neutron prima mergers. These outbursts – the astir energetic events successful the beingness since the large bang – were wide assumed to beryllium launched from the poles of the recently formed achromatic hole. But successful this case, the observed gamma-ray burst indispensable person emanated from the neutron prima itself, suggesting that an wholly antithetic process was astatine play.

Neutron stars are the smallest, densest stars successful existence, occupying a saccharine spot betwixt accepted stars and achromatic holes. They are astir 12 miles wide, and truthful dense that a spoon of worldly would person a wide of 1bn tonnes. They person a creaseless crust of axenic neutrons, 10bn times stronger than steel.

“They’re specified weird exotic objects,” said Prof Carole Mundell, an astronomer astatine the University of Bath and co-author of the study. “We can’t stitchery this worldly and bring it backmost to our laboratory truthful the lone mode we tin survey it is erstwhile they bash thing successful the entity that we tin observe.”

In this case, Mundell said, thing appears to person prevented the neutron prima “noticing however monolithic it is”. One anticipation is that the prima was spinning truthful accelerated and with specified immense magnetic fields that its illness was delayed – thing similar however h2o stays wrong a tilted bucket if it is swung astir accelerated enough.

“This is the archetypal nonstop glimpse that we whitethorn person of a hypermassive spinning neutron prima successful nature,” said Mundell. “My hunch is we’ll beryllium uncovering much of them.”

The unexpected sightings were made utilizing Nasa’s orbiting Neil Gehrels Swift Observatory, which detected the archetypal gamma-ray burst coming from a postulation astir 10.6bn airy years away. A robotic observatory, the Liverpool Telescope, situated successful the Canary Islands, past automatically swivelled to presumption the aftermath of the merger. These observations revealed telltale signatures of a highly magnetised, rapidly spinning neutron star.

This suggests that the neutron prima itself launched the gamma-ray burst, alternatively than it occurring aft its gravitational collapse. Until now, the nonstop series of events has been hard to fig out.

“We were excited to drawback the precise aboriginal optical airy from this abbreviated gamma-ray burst – thing that is inactive mostly intolerable to bash without utilizing a robotic telescope,” said Mundell. “Our find opens caller anticipation for upcoming entity surveys with telescopes specified arsenic the Rubin Observatory LSST, with which we whitethorn find signals from hundreds of thousands of specified long-lived neutron stars earlier they illness to go achromatic holes.”

Stefano Covino, an astronomer astatine the Brera Astronomical Observatory successful Milan, who was not progressive successful the research, said: “The squad recovered grounds of the beingness of a meta-stable hypermassive neutron star, which is simply a truly important finding.”

He said the enactment could supply caller insights into the interior operation of neutron stars, which are assumed to person a halfway of exotic matter, though the nonstop signifier that this takes is unknown.

The findings are published successful the Astrophysical Journal.