The best look ever at a giant flare

Brilliant magnetar eruption in the neighboring galaxies could aid search in the Milky Way.

In April 2020, astronomers detected an intense flash of light from an erupting neutron star in a nearby galaxy. The discovery offers astronomers their first clear look at a type of gamma-ray burst known as a magnetar giant flare.

Various space-based instruments, including NASA’s Fermi Gamma-beam Space Telescope, estimated a concise eruption of high-recurrence light that moved through the solar system on April 15.

Astrophysicist Matthew Baring, a professor of physics and astronomy at Rice University, said“Giant flares start with an intense flash that lasts about a tenth of a second, and for that brief instant, the amount of energy they release in gamma-rays is about 10 trillion to 100 trillion times the energy of the optical light from our sun.”

“When giant flares are close by, their initial burst of radiation saturates the instruments and blinds them so they cannot do things like measure the spectrum very easily.”

“The 2020 event was associated with the Sculptor Galaxy, NGC 253, about 50-60 times more distant than 1979. Even though it was intrinsically bright, it was far enough away that our instrument, the Fermi Gamma-Ray Burst Monitor, got a perfect look, a view that we have never had before of that first initial flash from a giant flare. the spectroscopic data revealed a wealth of information about the magnetic eruption that caused the flare.”

“The event had a lot of high-frequency photons with energies around 1 million electron volts, energies far greater than those of persistent X-ray light at around 2,000 electron volts, which is typically emitted from the surface of magnetar. We view this as a very clear signature of a giant flare.”

“The highest-energy light, around 3 million electron volts, “tells us that the plasma must be moving relativistically and emitting in an extended region, at the scale of perhaps 100 times the radius of the neutron star. And the only way it can easily do that is for the radiating plasma to be above the magnetic pole of the star.”

Spectroscopic data from the April 15 giant flare will allow physicists to test theoretical models of magnetars that haven’t previously been verifiable and could lead to a fuller understanding of not only magnetars but of the ways intense magnetic fields influence fundamental aspects of quantum mechanics.

“It’s possible that we may be able to disentangle physics elements from the global confusion associated with different magnetic field directions and different photon energies and different particle energies and say, ‘Aha, we found something new.'”

“What we learn could have an impact, for example, on how we deliver quantum field theory in the early universe, how we adapt it to conditions in the first few seconds of the universe.”

Additional co-authors of the Nature study include Oliver Roberts of the University Space Research Association, Peter Veres, Michael Briggs, Narayana Bhat and Rachel Hamburg of the University of Alabama in Huntsville, Chryssa Kouveliotou, George Younes, Sarah Chastain and Alexander van der Horst of George Washington University, James DeLaunay and Jamie Kennea of Pennsylvania State University, Daniela Huppenkothen of the University of Amsterdam, Aaron Tohuvavohu of the University of Toronto, Elisabetta Bissaldi of the University of Bari, Ersin Göğüş of Sabançi University, Daniel Kocevski of NASA’s Goddard Space Flight Center, Justin Linford of the National Radio Astronomy Observatory, Sylvain Guiriec of both George Washington University and NASA’s Goddard Space Flight Center, Colleen Wilson-Hodge of NASA’s Marshall Space Flight Center and Eric Burns of Louisiana State University.

Journal Reference:
  1. Roberts, O.J., Veres, P., Baring, M.G., et al. Rapid spectral variability of a giant flare from a magnetar in NGC 253. Nature 589, 207–210 (2021). DOI: 10.1038/s41586-020-03077-8

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