Binary Dynamics and Mergers in a Stellar Disk and the Formation of Dusty Objects in the Galactic Center

Abstract

For more than a decade, observers have been tracking a population of enigmatic dusty objects orbiting the central supermassive black hole of the Milky Way, Sagittarius A${}^{\star }$ (SgrA${}^{\star }$). In one interpretation, these objects are products of stellar mergers enshrouded in gaseous-dusty envelopes, which account for their infrared excess, emission lines, and stability against the tidal forces of SgrA${}^{\star }$. Recent near-infrared observations of D9, one of the dusty objects, revealed that it embeds a spectroscopic stellar binary. In this work, we present full-fledged N-body simulations of an eccentric disk of binary stars similar to the young stellar disk observed around SgrA${}^{\star }$. We find that some of the binaries in the disk are naturally drawn towards SgrA${}^{\star }$ and merge there due to Kozai-Lidov (KL) oscillations in their orbits. Together with the observed nature of D9, these findings represent a self-consistent picture of how the population of the observed dusty objects could have been brought into existence. The binary fraction in our N-body model evolves to increase with distance from SgrA${}^{\star }$, which is also in agreement with the observational constraints. Our simulations also suggest that beside the dusty objects, stellar mergers are present within the young stellar disk, which could be identified as chemically peculiar or fast-rotating stars. Our results show that dynamical evolution of binary stars in the young stellar disk plays a crucial role in shaping the stellar content in the Galactic Center.

arXiv comment22 pages, 9 figures, Published in ApJ

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