"Planet Nine" could be a black hole | Science

For nearly 5 years, more and more scientists have attributed to strange orbits of distant objects in the solar system the gravitational effects of an unexplored "Planet Nine", located in the realm of ice, well beyond Neptune. But a couple of physicists are now launching a fascinating idea that could offer a new way of looking for the object: what will happen if this supposed planet is actually a small black hole?

Previous studies have suggested that Planet Nine, which some astronomers call "Planet X", would have a mass five to fifteen times greater than Earth's and would be between 45 billion and 150 billion kilometers from the sun. At such a distance, an object would receive very little sunlight, making vision difficult with telescopes.

To detect objects of this mass, whether it's planets or black holes, astronomers can look for strange light drops formed when light "curves" around the gravitational field of the planet. object on his journey to Earth (simulated image above). These anomalies came and went when Planet Nine moved in front of a distant star and continued on its orbit.

But if the object is a black hole of planetary mass, say physicists, it would probably be surrounded by a halo of dark matter that could extend over 1 billion kilometers on either side. And the interactions between the dark matter particles in this halo, especially the collisions between dark matter and dark antimatter, could emit a gamma ray lightning that would betray the presence of the object, propose the researchers in a forthcoming article published on the preprint server arXiv.

Physicists will soon begin to analyze publicly available data from the Fermi Earth-bound orbiting Fermi Gamma-ray Space Telescope, which has been covering the sky in all directions since 2008. In particular, they will be looking for sporadic gamma flash units. slowly in the sky, as one would expect Planet Nine to observe it from the Earth. Although the physicists' proposal is speculative, their research can provide all kinds of information about dark matter and gamma ray light sources – whether they are in our solar system or in the universe.