Intermediate mass black holes: astrophysics and cosmology

In the Galaxy, about a hundred black hole (BH) candidates in close binaries are known. The main feature of a BH in a close binary is a high dynamical mass of the invisible component and the lack of the presence of a solid surface. Supermassive black holes in galactic nuclei (SMBHs) are also known, with the most studied being Sgr A* in the center of the Milky Way and M87*. Since 2015, gravitational wave (GW) signals from merging binary BHs with masses up to 100 solar masses have also been observed. Intermediate mass black holes (IMBHs) are hypothetical objects that may be located in the centers of globular clusters and dwarf galaxies. We consider a possible model for the primordial IMBH formation from curvature perturbations created during the inflationary stage with additional complex scalar field with a baryon charge. We consider the possibility of recording the GW signal from double IMBHs in mHz range by future space GW interferometers (LISA, TaiJi, TianQin), as well as their possible connection with the population of double MBHs recorded by ground-based GW-detectors.