General concept of the project

Our project is dedicated to the detailed dynamical study of three spatial zones of the Galaxy. The novelty and unique feature is a combination of these zones into one dynamically interconnected system, by using a powerful computational facility available to the current project. Each of these components contain very large numbers of particles and therefore they have been studied in numerical models separately from each other. Besides, we will analyze the long-term cosmological evolution of the Galactic center (GC) which plays a dominant role in Galaxy life. In fact, up to now the theoretical description of GC lacked the needed realism. We tightly connect our numerical models with recent observational data (tidal disruption events and gas accretion events, gravitational wave emission, hypervelocity stars). Complex description will provide us the unique opportunity to understand the physical picture of Galaxy global evolution.

Goal of the project

Development of a unify picture of dynamical evolution of GC based on a multi-component time-evolved Galaxy model and to compare obtained numerical models with the up-to-date observations of the MW GC system

Expected results

We will provide a detailed dynamical simulation of the Milky Way GSC system in the time variable external tidal field. In detail we analyze the interaction between the individual GSC’s with the central SMBH if the GSC comes closer as 100 pc to the MW center. For this selected sample of GSC’s we compute the detailed direct N-body evolution of these systems. Combined in one timeline all of these events we estimate the global star in-fall rate on to the core zone of MW GC. We also perform the deeper analysis of the GSC’s mass loss (including the tidal tails dynamics) and the tidal debris interactions (stars accretion on to the SMBH).
After that we use our previous results as initial and boundary conditions (individual star in-fall rate) to model with high resolution the inner (1 – 2 pc) zone GC. These stars on the time scale of few Gyr form in the end our current MW NSC as we see this today. The study of the formation and density distribution and also the stability of such a cluster will be one of our main tasks in this part of our Project. The detailed resulting history of the NSC stellar content (possible mass segregation) including stellar mass black holes and neutron stars will be in our focus.
We will obtain the close interaction history between individual GSC’s stellar content and the central SMBH, including the detailed simulation of the TDE and PTDE of individual stars from the GSC’s. We will pay special attention to the interaction between the central SMBH and the GSC’s compact objects population, like neutron stars and stellar mass black holes.
Here are a few examples of the main scientific issues that will be addressed in the framework of this Project.
Search for millisecond pulsars in the center of the Galaxy. The pulsation period of these objects is extremely small, on the order of 1/1000 second (hence the name), therefore, any deviation from the accuracy of the pulsation period indicates a gravitational perturbation. Thus, a millisecond pulsar in the immediate vicinity of the SMBH is the cornerstone for testing the general theory of relativity in the regime of strong gravity. Based on the results of this Project, we will provide data on possible orbits of pulsars in the Galactic Center.
Tidal disruption events – TDE and partial TDE. To date, theoretical estimates of the rate of tidal destruction events do not correspond to observational data. The number of registered phenomena is orders of magnitude smaller than what the literature predicts. Within the framework of the Project, using the results of numerical simulations of the evolution of galactic centers, we will be able to quantify the temporal rate of these events, which should resolve the contradiction.
Detection of gravitational waves. Of particular interest is the merging of black holes in gaseous accretion disk. Based on the analysis of the evolutionary models obtained in the framework of the Project, we will provide statistical description of the parameters of black holes and neutron stars during mergers.
The formation of hypervelocity stars. When a binary star approaches an SMBH, one of the binary components can be captured by the black hole, giving the second component a higher speed. Thus, having discovered such stars, it is possible to estimate the galactic potential, measure the mass of the SMBH, and estimate the mass distribution of the Galaxy. Within the framework of this project, the orbits and the rate of formation of hypervelocity stars will be presented, which will greatly simplify their search in the Gaia extensive data catalog.
In turn, the dataset from the numerical models will also be made publicly available, thereby making it possible to verify the findings. Moreover, open access will allow other scientists to conduct further research based on existing data. The data processing utilities will be published on in open access. All of our main results we will publish in international astronomical journals and present at the international astronomical meetings. The history of close interactions of the stellar content of GC we present on a special database with the web page access.