Artist's impression of a supermassive black hole.

-

Caltech / R.

Hurt (IPAC) / Cover Ima / SIPA

Australian scientists have announced the detection of a very rare species of black hole, of intermediate size, by an unprecedented technique that betrayed its presence, according to a study by Australian physicists published on Monday in

Nature Astronomy

.

"This is the first evidence of the existence of an intermediate-sized black hole of such a mass," reaching that of 55,000 suns, said a doctoral student at the School of Physics at the University of Melbourne.

If the discovery is confirmed, it will fill a void that puzzles black hole physics.

Theorized by Einstein, this object concentrates its matter with such density that it prevents even light from escaping its gravitational force.

Only two families are really known to date, radically different in size.

Indices of their existence for a few years

Stellar black holes, small thumbs formed by the collapse of a dying star on itself, whose mass is up to ten that of our sun.

And at the other end, ogres lurk in the heart of every galaxy, the supermassive black holes.

Like "the one at the center of our Milky Way, which makes a few million solar masses," explained the deputy director of the Institute for Millimeter Radio Astronomy.

The most massive reach several billion solar masses.

Quite logically, "we therefore wondered if there were not black holes of intermediate mass", adds the astrophysicist.

And if these would not play a role in the genesis of their supermassive congeners.

The authors of the study note that the signs of their existence have been accumulating for a few years.

Scientists announced last September the discovery of a first black hole of intermediate mass, of only 145 solar masses.

Almost 40,000 black holes of this type in our galaxy?

"It troubles everyone, because we are looking for something of an order of magnitude between tens and millions of solar masses," notes the scientist.

The Australians have reportedly hit a more promising target by identifying and analyzing gamma-ray burst data.

These extraordinarily powerful flashes of light come from events such as the explosion of massive stars.

One of them, GRB 950830, apparently had a funny encounter on the way to our Earth, from its place of emission, billions of light years away, "in the early ages of the Universe ”.

Its light signal was recorded with a sort of echo, caused by its passage near a black hole, which acted as a "gravitational lens": the mass of the black hole is so large that it deforms the structure of space-time and bends the path of light passing in its proximity, doubling it.

It is the measurement of this shift which would have made it possible to reveal the presence of the black hole and its theoretical mass.

"We estimate that there could be 40,000 intermediate black holes in our galaxy," said an astrophysicist professor and co-author of the study.

For his colleague from Australian University Monash, it could be a "primordial black hole", created in the childhood of the Universe.

With an enormous mass, these objects could have been "the precursors of supermassive black holes", the origin of which remains unexplained, he wrote in a press release.

Science

The giant black hole M87 begins to reveal its secrets

Science

Giant radiogalaxies: recent discoveries enrich our understanding of the universe

  • Science

  • Scientists

  • Research

  • Astronomy

  • Black hole