De minuscules trous noirs expliquent les flux de galaxies et l'expansion de l'univers express
La matière noire n'est peut-être pas faite de particules, mais de trous noirs datant du Big Bang. Dans l'univers primordial, semblable à une pâte que l'on pétrit, ils étaient comme de lourds grains – presque immobiles, ils rassemblaient la matière autour d'eux et la faisaient tourbillonner en flux rapides de galaxies, que les astronomes observent aujourd'hui. Mais il y a un détail : les trous les plus légers, selon la théorie de Hawking, s'évaporent en émettant de l'énergie. Cette évaporation réchauffe légèrement la « pâte » cosmique aux premiers stades, ce qui modifie la vitesse calculée de l'expansion de l'univers et atténue la fameuse tension entre les différentes méthodes de mesure.
Résumé original
tel que rédigé par les auteurs, en anglais arXiv:2601.07106
The high value of the cosmic microwave dipole may be telling us that dark matter is macroscopic rather than a fundamental particle. The possible presence of a significant dark matter component in the form of primordial black holes suggests that dark halo formation simulations should be commenced well before redshift z = 100. Unlike standard CDM candidates, PBHs behave as dense, non-relativistic matter from their inception in the radiation-dominated era. This allows them to seed gravitational potential wells and begin clustering earlier. We find that starting N-body simulations at redshifts even before matter-radiation equality yield galaxy bulk flow velocities that are systematically larger than those predicted by standard LCDM models. The early, high-mass concentrations established by PBHs lead to a more rapid and efficient gravitational acceleration of surrounding baryonic and dark matter, generating larger peculiar velocities that remain coherent over scales of hundreds of Mpc. Furthermore, a sub-population of PBHs in the 10^-20 to 10^-17 solar mass range would lose a non-negligible fraction of their mass via Hawking radiation over cosmological timescales. This evaporation process converts matter into radiation, so a time-varying matter density parameter, Omega_m', is introduced, which behaves like a boosted radiation term in the Friedmann equation. This dynamic term acts to reduce the Hubble tension. A higher effective Omega_r in the early universe reduces the sound horizon at the epoch of recombination. PBH mass loss also influences fits to the equation of state parameter, w, at low redshift. The naive N-body modelling presented here suggests investigation with tried and tested cosmology codes should be carried out, by introducing mass losing PBHs and starting the evolution as early as practicable.
Un de ces trous pèse comme un astéroïde, mais est comprimé en un point plus petit qu'un noyau atomique. Son évaporation est si lente que, sur toute l'histoire de l'univers, il n'aurait perdu qu'une infime partie de sa masse.