How the nucleus of a galaxy forms?
A study coordinated by Wisdom (first author Manuel Arca Sedda University of Tor Vergata), investigated the formation of the core of galaxies like ours, and in particular on the relationship between supermassive black holes (SMBH) and nuclear star clusters (NSC).
Galaxies like the Milky Way, which belongs to our solar system, are the focuses of an enormous amount of stellar phenomena unknown waiting to be included. A study coordinated by Wisdom (first author Manuel Arca Sedda University of Tor Vergata), investigated the formation of the core of these galaxies, and in particular on the relationship between supermassive black holes (SMBH) and nuclear star clusters (NSC). Although their existence is well established, it is still unclear what relationship binds SMBH and NSC, nor what role, if with respect to the process of formation of the other.
One of the possible scenarios is the migration pattern, according to which the NSC would be formed by the collision of star clusters, huge aggregates, which may contain up to a million stars that reach the inner areas of the galaxies in which they are contained due to the mechanism physicist called dynamic friction.
In this context, the research, published in The Astrophysical Journal, examines the process of formation of a nuclear star cluster around a black hole, much like the one contained in the Milky Way, using sophisticated computer simulations that allowed, for the first time, to reproduce the evolution of a galactic nucleus with a level of resolution never reached.
In particular, to model the host galaxy, have been used very recent observations of Henize 2-10, a galaxy located 34 million light years away in the constellation Pisces. This galaxy hosts inside a super massive black hole similar to that of our galaxy and 11 star clusters that orbit, and thus represents a unique laboratory for studying the mechanism of formation of a mass nuclear stellar compatible with that of our Milky Way.
From what has been observed, the migration pattern very well reproduces the mechanism of formation of NSC, pointing out that it may also take place in the presence of a pre-existing SMBH. The results obtained suggest that black holes and super massive nuclear stellar clusters, although interact significantly, most likely do not share the same formation mechanism.
“The research uses information data as input for computer simulations that aim to predict the future evolution of a galaxy like ours, contains a super-massive black hole at the center,” says Roberto Capuzzo Lamb, Professor of Astrophysics at the Sapienza, “and it represents an important step towards a more complete understanding of the phenomena of creation of the nuclei of galaxies, supermassive black holes present there, as well as the very special physical processes occurring there.”