Astronomers noticed colliding neutron stars which will have shaped a magnetar

A surprisingly vivid cosmic blast may need marked the start of a magnetar. In that case, it could be the primary time that astronomers have witnessed the formation of this type of quickly spinning, extraordinarily magnetized stellar corpse.

That dazzling flash of sunshine was made when two neutron stars collided and merged into one large object, astronomers report in an upcoming difficulty of the Astrophysical Journal. Although the particularly vivid mild might imply {that a} magnetar was produced, different explanations are potential, the researchers say.

Astrophysicist Wen-fai Fong of Northwestern College in Evanston, Ailing., and colleagues first noticed the location of the neutron star crash as a burst of gamma-ray mild detected with NASA’s orbiting Neil Gehrels Swift Observatory on Might 22. Comply with-up observations in X-ray, seen and infrared wavelengths of sunshine confirmed that the gamma rays have been accompanied by a attribute glow referred to as a kilonova.

Kilonovas are thought to kind after two neutron stars, the ultradense cores of lifeless stars, collide and merge. The merger sprays neutron-rich materials “not seen anyplace else within the universe” across the collision website, Fong says. That materials rapidly produces unstable heavy parts, and people parts quickly decay, heating the neutron cloud and making it glow in optical and infrared mild (SN: 10/23/19).

A brand new examine finds that two neutron stars collided and merged, producing an particularly vivid flash of sunshine and presumably making a form of quickly spinning, extraordinarily magnetized stellar corpse referred to as a magnetar (proven on this animation). Astronomers suppose that kilonovas kind each time a pair of neutron stars merge. However mergers produce different, brighter mild as properly, which may swamp the kilonova sign. In consequence, astronomers have seen just one definitive kilonova earlier than, in August 2017, although there are different potential candidates (SN: 10/16/17).

The glow that Fong’s workforce noticed, nevertheless, put the 2017 kilonova to disgrace. “It’s probably probably the most luminous kilonova that we’ve ever seen,” she says. “It mainly breaks our understanding of the luminosities and brightnesses that kilonovae are alleged to have.”

The largest distinction in brightness was in infrared mild, measured by the Hubble Area Telescope about three and 16 days after the gamma-ray burst. That mild was 10 instances as vivid as infrared mild seen in earlier neutron star mergers.

“That was the true eye-opening second, and that’s after we scrambled to search out a proof,” Fong says. “We needed to give you an additional source [of energy] that was boosting that kilonova.”

Her favourite clarification is that the crash produced a magnetar, which is a sort of neutron star. Usually, when neutron stars merge, the mega-neutron star that they produce is just too heavy to outlive. Virtually instantly, the star succumbs to intense gravitational forces and produces a black gap.

But when the supermassive neutron star is spinning quickly and is extremely magnetically charged (in different phrases, is a magnetar), it might save itself from collapsing. Each the help of its personal rotation and dumping power, and thus some mass, into the encircling neutron-rich cloud might hold the star from turning right into a black gap, the researchers counsel. That further power in flip would make the cloud give off extra mild — the additional infrared glow that Hubble noticed.

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However there are different potential explanations for the additional vivid mild, Fong says. If the colliding neutron stars produced a black gap, that black gap might have launched a jet of charged plasma transferring at practically the pace of sunshine (SN: 2/22/19). The main points of how the jet interacts with the neutron-rich materials surrounding the collision website might additionally clarify the additional kilonova glow, she says.

If a magnetar was produced, “that would inform us one thing concerning the stability of neutron stars and the way large they will get,” Fong says. “We don’t know the utmost mass of neutron stars, however we do know that usually they might collapse right into a black gap [after a merger]. If a neutron star did survive, it tells us about beneath what circumstances a neutron star can exist.”

Discovering a child magnetar could be thrilling, says astrophysicist Om Sharan Salafia of Italy’s Nationwide Institute for Astrophysics in Merate, who was not concerned within the new analysis. “A new child extremely magnetized, extremely rotating neutron star that kinds from the merger of two neutron stars has by no means been noticed earlier than,” he says.

However he agrees that it’s too quickly to rule out different explanations. What’s extra, current pc simulations counsel that it is likely to be troublesome to see a new child magnetar even when it shaped, he says. “I wouldn’t say that is settled.”

Observing how the thing’s mild behaves over the subsequent 4 months to 6 years, Fong and her colleagues have calculated, will show whether or not or not a magnetar was born.

Fong herself plans to maintain following up on the mysterious object with present and future observatories for a very long time. “I’ll be monitoring this until I’m outdated and gray, most likely,” she says. “I’ll prepare my college students to do it, and their college students.”

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