Our aim is deepening the knowledge of the physics of the inner few parsecs of our Galaxy and of other galaxies.
Actually, the central regions of galaxies are very peculiar places, sites of exotic objects like super massive black holes (SMBHs) and very massive and dense stellar clusters (Nuclear Star Clusters, NSCs).
With this project, we intend to understand better the inter-relation between the local, small, space-time scales and those of the overall galactic environment.
Galactic nuclei have sizes of ~ 10 pc and crossing times of few Myrs while galaxies extend to tens of kpc and orbital periods are Gyr long.
The existence of these correlations is indirectly proven by the evidence of a strong connection between the masses of SMBHs and the mass of the parent galaxy, as well by the evidence of a similar correlation for the NSC mass and the galaxy mass, although with different slope.
Moreover, observations of the so called "hyper velocity stars" (HVSs) in the Galactic halo seem to find an explanation just by mean of an acceleration mechanism caused by the central SMBH.
Our research will develop on the attempt to interpret i) the formation and evolution of galactic nuclei and their stellar and black hole content, ii) their scaling correlations with the hosting galaxy; iii) the origin of HVSs and of the S-stars (the ones which orbit fast around the Galactic geometric center), as well as iv) check the possibility that either HVSs keep bound around them some revolving planets or they release them to the background as hypervelocity planets (HVPs).
This project is a natural development of a research that has been progressing for years and that has already produced relevant results and numerous publications at international level.
The proposed project has specific innovative points, on the sides of the topics, aims (Physics and Astrophysics) and methods (algorithms and numerical methods) to use.
Topics: the study of inner galactic regions around massive and supermassive black holes is a highly debated topic in modern Astrophysics. Actually, a proper treatment of the topic of high- and hyper-velocity stars and planets in our Milky Way and other galaxies is still uncovered by previous researches.
The interpretation, also, of the numerous data concerning the distribution of different types of stars (including RR Lyrae pulsators) in the galactic bulge is a modern topic which we attack in this project.
Aims: the understanding of formation of NSCs and SMBHs, in the frame of violent dynamics in the inner galactic regions is an open question. In particular, one unsolved puzzle is that of the stability of the observed NSCs in galaxies.
Most of the galaxies borrow CMOs at their center, but there is a difference between very dense nuclear clusters and super massive black holes. It remains to understand if the missing evidence of NSCs in bright galactic hosts may be related to their collapse due to insufficient kinetic energy source to support the "heavy" gravitational structure.
Also the topic of generation of HVS with their planetary systems is new, as well as that of understanding the dynamical behavior of the "zoo" of compact objects strongly interacting in dense stellar environments.
A novel topic is that of the possible subsequent merging events of lighter black holes, to build up an eventual super massive black hole.
Methods: we use state of the art dynamical simulations by means of direct summation, high precision codes developed in our group (HiGPUs, NBSymple, ARchain) or upon this specific collaboration (NBODY6++, phiGPU) or freely available (NBODY6, NBODY7) . We will make use of both local (owned by the ASTRO group, lead by the project PI) computing platforms (CPU+GPUs hybrid systems) and huge parallel main frames via computing grants (Gauss Centre for supercomputing, Julich, Germany).