Nasa surprised a reversal of the magnetic field that surrounds a monstrous black hole

A galaxy whose luminosity suddenly begins to change inevitably catches the eye of researchers. A veritable explosion of visible light. And even ultraviolet. Then a mysterious disappearance of the emissions of certain X-rays. Before a return to normal. Enough to tie knots in the brains of researchers. But astronomers are now offering an explanation. The person responsible would be to be sought on the side of the supermassive black hole at the center of this galaxy and its magnetic field.

Many times in history, the earth’s magnetic field reversed. The last time was around 780,000 years ago. The magnetic field of Sun, it reverses much more regularly. Every 11 years. But what NASA researchers think they have observed this time is of a whole different dimension. Neither more nor less than the reversal of the magnetic field that surrounds a supermassive black hole. All some 236 million light-years from our Solar system.

The alert was given in March 2018, when the All-Sky Automated Survey for Supernovae reported that the galaxy named 1ES 1927+654 appeared nearly 100 times brighter than it should. in the realm of the visible. The astronomers then went in search of earlier data that would help date the change of brightness. They went back to the end of 2017.

The researchers then turned the swift space telescope towards this strange galaxy. In May 2018, he reported that the ultraviolet (UV) emission of 1ES 1927+654 had increased twelvefold. But that she was shrinking. A few weeks later, in June, the broadcast of X-rays of higher energy simply disappeared.

For supermassive black holes as for the Sun or the Earth

Astronomers first thought they had surprised a star being devoured by the supermassive black hole which nestles in the heart of 1ES 1927+654. Let us recall that when matter falls towards a black hole which sometimes weighs billions — here, a priori, twenty million — times the mass of our Sun, it begins by accumulating in one accretion disk. As it swirls inward, it then emits light visible, UV and low energy X-rays. Closer to the black hole, the extremely hot material forming the corona emits higher energy X-rays. All with an intensity that depends on the amount of matter that falls on the supermassive black hole. The problem is that the phenomenon should have faded much more quickly than what the researchers observed on this galaxy.

And the fact that the X-rays momentarily disappeared completely put them on a completely different track. That of a magnetic field reversal. What astronomers do indeed believe is that the magnetic field of a supermassive black hole creates and maintains its corona. Thus any change in this field would result in observable changes in the emissions of X-rays high energy.

According to the model that the researchers have developed, in the case of a magnetic field inversion, said magnetic field would begin to weaken at the periphery of the accretion disk, leading to heating and therefore an increase in emissions in the visible and in the the UVs. As the reversal progressed, the magnetic field would eventually weaken so much that it could no longer sustain the corona. The high energy X emissions would disappear. Then when the reverse field would begin to regain strength, these emissions would resume. This is what astronomers observed in October 2018. And by the summer of 2021, the galaxy had completely returned to its previous state.

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