Relaxation near supermassive black holes driven by nuclear spiral arms: anisotropic hypervelocity stars, S-stars and tidal disruption events

Abstract

Nuclear spiral arms are small-scale transient spiral structures found in the centers of galaxies. Similarly to their galactic-scale counterparts, nuclear spiral arms can perturb the orbits of stars. In the case of the Galactic Center (GC), these perturbations can affect the orbits of stars and binaries in a region extending to several hundred parsecs around the supermassive black hole (MBH), causing diffusion in orbital energy and angular momentum. This diffusion process can drive stars and binaries to close approaches with the MBH, disrupting single stars in tidal disruption events (TDEs), or disrupting binaries, leaving a star tightly bound to the MBH, and an unbound star escaping the galaxy, i.e., a hypervelocity star (HVS). Here, we consider diffusion by nuclear spiral arms in galactic nuclei, specifying to the Milky Way GC. We determine nuclear spiral arm-driven diffusion rates using test-particle integrations, and compute disruption rates. Our TDE rates are up to 20% higher compared to relaxation by single stars. For binaries, the enhancement is up to a factor of ~100, and our rates are comparable to the observed numbers of HVSs and S-stars. Our scenario is complementary to relaxation driven by massive perturbers. In addition, our rates depend on the inclination of the binary with respect to the Galactic plane. Therefore, our scenario provides a novel potential source for the observed anisotropic distribution of HVSs. Nuclear spiral arms may also be important for accelerating the coalescence of binary MBHs, and for supplying nuclear star clusters with stars and gas.

Accepted for publication in ApJ. 21 pages, 18 figures

References in corpus (10)

• The Two Young Star Disks in the Central Parsec of the Galaxy: Properties, Dynamics and Formation
• An Improved Distance and Mass Estimate for Sgr A* from a Multistar Orbit Analysis
• Nuclear spirals as feeding channels to the Supermassive Black Hole: the case of the galaxy NGC 6951
• Streaming Motions Towards the Supermassive Black Hole in NGC 1097
• Dynamical evolution of the young stars in the Galactic center: N-body simulations of the S-stars
• Dynamical and evolutionary constraints on the nature and origin of hypervelocity stars
• Massive perturbers and the efficient merger of binary massive black holes
• Hypervelocity stars from young stellar clusters in the Galactic Centre
• Relativistic dynamics of stars near a supermassive black hole
• Probing the formation of planetesimals in the Galactic Centre using Sgr A* flares

Cited by in corpus (13)

• Rates of Stellar Tidal Disruption
• Interacting Stellar EMRIs as Sources of Quasi-Periodic Eruptions in Galactic Nuclei
• Nearby high-speed stars in Gaia DR2
• Hypervelocity Stars from a Supermassive Black Hole-Intermediate-mass Black Hole binary
• Embedding planetesimals into white dwarf discs from large distances
• Extreme mass-ratio gravitational-wave sources: Mass segregation and post binary tidal-disruption captures
• Spectral features of tidal-disruption candidates and alternative origins for such transient flares
• Impact of the Galactic Disk and Large Magellanic Cloud on the Trajectories of Hypervelocity Stars Ejected from the Galactic Center
• Properties and applications of a predicted population of runaway He-sdO/B stars ejected from single degenerate He-donor SNe
• Constraints on the origins of hypervelocity stars: velocity distribution, mergers and star-formation history
• The S stars' zone of avoidance in the Galactic center
• The former companion of the hyper-velocity star S5-HVS1
• The Delay Time Distribution of Tidal Disruption Events