According to a team of NASA scientists in their recent study published in The Astrophysical Journal , a colossal black hole seems to have made a magnetic turn of 180 °. They came to this theory after observing a mysterious cosmic outburst in a galaxy 236 million light-years away from Earth. The team believes that the unusual features of the eruption are linked to changes observed in the vicinity of the black hole that suggest it has undergone a magnetic spin: it has flipped over.
Magnetic reversal of a black hole
It was in March 2018 , when astronomers observed a sudden change in brightness in a galaxy located 239 million light-years away. Known as 1ES 1927+654, the galaxy brightened in visible light and further observation by the NASA-funded Asteroid Earth-impact Last Alert System revealed that the eruption began much earlier, in late 2017.
The new analysis of the galaxy carried out in May 2018 revealed an ultraviolet emission elevated up to 12 times. At that time, the brightness level was continuously decreasing. Then, in June, the galaxy’s highest-energy X-ray emission simply disappeared.
What was this broadcast?
The researchers suspect that the black hole’s magnetic field creates and supports the corona, so any magnetic changes could affect its X-ray properties. In other words, the galaxy’s rare and enigmatic outburst may have been triggered by a magnetic reversal. , that is , a spontaneous change in the magnetic field surrounding its central black hole.
It’s the same type of magnetic reversal that our star, the Sun, experiences every 11-year cycle : the north and south poles are swapped as a result of a magnetic reversal as part of its normal cycle of activity. It is not a rare cosmic bird. Although in this case, there is a peculiarity:
“Rapid changes in visible and ultraviolet light have been seen in a few dozen galaxies similar to this one,” said Sibasish Laha, a research scientist at the University of Maryland, Baltimore County and NASA’s Goddard Space Flight Center in Greenbelt. , Md. “But this event marks the first time we’ve seen X-rays completely disappear while the other wavelengths light up.”
According to experts, if a magnetic reversal were to occur causing the black hole’s north pole to become the south pole and vice versa, visible and ultraviolet light should increase towards the center of the galaxy due to further heating, as the crown begins to shrink and the accretion disk becomes more compact in the center. Then, as the spin evolves, the magnetic field would become so weak that the corona could not hold on and the X-ray emissions would cease. Four months after the X-ray emissions disappeared, they returned, so the corona is supposed to would have restored after this change.
Regarding research, the research team analyzed new and archival observations across the spectrum. NASA’s Neil Gehrels Swift Observatory and ESA’s (European Space Agency) XMM-Newton satellite provided X-ray and UV measurements. The visible-light observations came from Italy’s 3.6-meter Galileo National Telescope and the 10.4-meter Gran Telescopio Canarias, both located on the island of La Palma in the Canary Islands, Spain. The radio measurements were acquired from the Very Long Baseline Array, a network of 10 radio telescopes located in the United States; the Very Large Array in New Mexico; and the European VLBI Network .
Referencia: “A radio, optical, UV and X-ray view of the enigmatic changing look Active Galactic Nucleus 1ES~1927+654 from its pre- to post-flare states” by Sibasish Laha (NASA-GSFC), Eileen Meyer, Agniva Roychowdhury, Josefa Becerra González, J. A. Acosta-Pulido, Aditya Thapa, Ritesh Ghosh, Ehud Behar, Luigi C. Gallo, Gerard A. Kriss, Francesca Panessa, Stefano Bianchi, Fabio La Franca, Nicolas Scepi, Mitchell C. Begelman, Anna Lia Longinotti, Elisabeta Lusso, Samantha Oates, Matt Nicholl and S. Bradley Cenko, Accepted, The Astrophysical Journal. arXiv:2203.07446
