Gravitational waves from stars orbiting the Sagittarius A* black hole

One of the main astrophysical processes leading to strong emission of gravitational waves to be detected by the future space-borne interferometer Laser Interferometer Space Antenna (LISA) is the capture of a compact star by a black hole with a mass of a few million solar masses in the center of a galaxy. In previous studies, main-sequence stars were thought not to contribute because they suffer from early tidal disruption. Here we show that according to our simulations of the stellar dynamics of the Sgr A* cluster, there must be one to a few low-mass main-sequence stars sufficiently bound to the central Galactic black hole to be conspicuous sources in LISA observations. The probability that a white dwarf may be detectable is lower than 0.5, and in spite of mass segregation, detection of a captured neutron star or stellar black hole in the center of the Milky Way is highly unlikely.