An international group of astrophysicists from the United States, Finland and the United Kingdom have explained the appearance of giant black holes, whose mass ranges from millions to billions of solar masses. Scientists have shown that they can form inside protogalaxies when star formation stops. The researchers' article was published in the journal Nature Astronomy.
According to the results of computer simulations, for the appearance and growth of supermassive black holes, it is necessary that there is a deficit of molecular hydrogen (H2) in the protogalaxy. The latter serves as matter for the formation of stars that could pull matter over themselves. The researchers found that a sufficient amount of Lyman-Werner radiation from neighboring galaxies can provoke the decay of H2.
The Lyman-Werner radiation consists of photons, which have enough energy for the H2 that has absorbed it to decay to form atomic hydrogen. Calculations have shown that these photons can be formed in galaxies with a burst of star formation. Such an active galaxy should be at a suitable distance from protogalaxies. In addition, the bombardment by photons must occur before the processes of compression of interstellar gas begin, leading to the appearance of black holes.
Astronomers, using a hydrodynamic model, calculated that the distance between a galaxy with a burst of star formation and a protogalaxy should be 200-300 parsecs, and the difference in their age should be less than four million years.