Weird, this giant black hole is spinning very slowly!

This is a record broken by this black hole: it is the most massive detected with a precise measurement of its spin. And the researchers deduced its rotation speed, which turns out to be extremely slow!

They are found in the center of each galaxy active, according to scientists. The supermassive black holes reach millions or even billions of solar masses. Their formation remains mysterious even today, but they can be characterized by few parameters. ” Each black hole can be defined by only two numbers: its spin and its masssaid Julia Sisk-Reynes from the Institute of Astronomy (IoA) at the University of Cambridge in the UK, who led a new study published in the journal Monthly Notices of the Royal Astronomical Society. “While it sounds simple enough, determining these values ​​for most black holes has proven to be incredibly difficult. »

That’s what Julia and her team did, observing X-rays bouncing off an accretion disk spinning around the quasar H1821+643. The latter turned out to be a supermassive black hole very strange: with a mass between 3 and 30 billion solar masses, it is one of the most massive ever discovered. But, strangely enough, rotation speed is nearly twice as small as those measured for black holes of mass similar to that of Sagittarius A*, the one that sits in the center of the Milky Way.

Clues to the formation of black holes

A phenomenon that researchers do not fully explain, but attribute to the formation of this black hole. Located at 3.4 billionlight years of the Earth, it could have been formed by mergers successive lower mass black holeswhether they are stellar, or intermediate. “The moderate rotation of this ultramassive object may be testimony to the violent and chaotic history of the largest black holes in the world.Universe, said co-author James Matthews, also from the IoA. It could also give a glimpse of what will happen to our Galaxy’s supermassive black hole billions of years in the future, when the Milky Way collides with Andromeda and other galaxies. » Indeed, during a fusion of this type, the rotation of the resulting black hole is modified by the numerous gravitational effects which twist the two monsters in interaction.