According to NASA scientists who proposed the theory, a colossal black hole may have done a 180 magnetic flip after observing a mysterious cosmic outburst in a galaxy 236 million light-years away.
The theory is detailed in a new study published in the Astrophysical Journal. The NASA team believes the unusual characteristics of the eruption are linked to changes observed in the black hole's vicinity that suggest a magnetic flip took place.
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Observing a black hole magnetic field reversal
Magnetic field reversals are relatively common occurrences in space. The Sun switches north and south poles roughly every 11 years as part of a cycle tied to a recent string of massive solar eruptions.
"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, Maryland. "But this event marks the first time we've seen X-rays dropping out completely while the other wavelengths brighten."
The scientists analyzed data from several telescopes for their research, including NASA's Neil Gehrels Swift Observatory and ESA's (European Space Agency) XMM-Newton satellite.
In early March 2018, astronomers noticed that a galaxy called 1ES 1927+654 had brightened almost a hundred times in visible light. Looking over archival data, they found that the eruption had actually started near the end of 2017. In June 2018, observations made by Swift showed that the galaxy's higher-energy X-ray emissions had disappeared completely.
A "strange explosive episode"
An earlier theory suggested that the eruption was triggered by a star destroyed by the black hole, though the researchers of the new study suggest such an event would have faded out at a faster rate than the one observed.
"It was very exciting to delve into this galaxy's strange explosive episode and try to understand the possible physical processes at work," said José Acosta-Pulido, a co-author at the Canary Islands Institute of Astrophysics (IAC) on Tenerife.
Scientists believe the black hole's magnetic field creates and sustains its corona so that any magnetic change could impact the X-ray properties observed on Earth. "A magnetic reversal, where the north pole becomes south and vice versa, seems to best fit the observations," said co-author Mitchell Begelman, a professor in the astrophysical and planetary sciences department at the University of Colorado Boulder. "The field initially weakens at the outskirts of the accretion disk, leading to greater heating and brightening in visible and UV light."
In this theory, as the flip takes place, the black hole's magnetic field momentarily becomes so weak it can no longer support the corona, which causes the complete disappearance of the X-ray emissions. In October 2018, roughly four months after the X-ray emissions disappeared, they returned, suggesting the corona had been restored after the flip took place.