Is there an intermediate massive black hole in the Galactic center: Imprints on the stellar tidal-disruption rate

Abstract

It has been suggested that an intermediate-massive black hole (IMBH) with mass $10^{3-5}{M}_{\odot }$ could fall into the galactic center (GC) and form a massive black hole binary (MBHB) with the central supermassive black hole, but current observations are not sensitive to constrain all mass and distance ranges. Motivated by the recent discovery that MBHBs could enhance the rate of tidal-disruption events (TDEs) of stellar objects, we investigate the prospect of using stellar-disruption rate to probe IMBHs in the GC. We incorporated the perturbation by an IMBH into the loss-cone theory and calculated the stellar-disruption rates in the GC. We found that an IMBH heavier than $2000M_{\odot }$ could distinguishably enhance the stellar-disruption rate. By comparing observations of Sgr A* with the fall-back model for stellar debris, we suggested that the TDE rate in our Galaxy should not significantly exceed $0.002y{r}^{-1}$, therefore a fraction of the parameter space for the IMBH, concentrating at the high-mass end, can already be excluded. To derive constraint in the remaining parameter space, it is crucial to observationally confirm or reject the stellar-disruption rate between $10^{-4}$ and $10^{-2}y{r}^{-1}$, and we discussed possible strategies to make such measurements.

17 pages, 2 figures; a few typos are corrected to match the published version in ApJ

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• A rapid evolving region in the Galactic Center: Why S-stars thermalize and more massive stars are missing
• The Combined Effects of Two-Body Relaxation Processes and the Eccentric Kozai-Lidov Mechanism on the EMRI Rate
• Detecting Kozai-Lidov imprints on the gravitational waves of intermediate-mass black holes in galactic nuclei
• The role of stellar relaxation in the formation and evolution of the first massive black holes
• The fragmenting past of the disk at the Galactic Center : The culprit for the missing red giants
• Formation of Dark Matter Torii Around Supermassive Black Holes Via The Eccentric Kozai-Lidov Mechanism
• A Stability Timescale for Non-Hierarchical Three-Body Systems
• Constraining a companion of the galactic center black hole, Sgr A*
• Our Supermassive Black Hole Rivaled the Sun in the Ancient X-ray Sky
• Sculpting the Stellar Cusp in the Galactic Center
• Astrophysics with the Laser Interferometer Space Antenna
• Partial Tidal Disruption Events by Intermediate-mass Black Holes in Supermassive and Intermediate-mass Black Hole Binaries
• A Recent Supermassive Black Hole Binary in the Galactic Center Unveiled by the Hypervelocity Stars
• Resonant Dynamical Friction in Nuclear Star Clusters: Rapid Alignment of an Intermediate-mass Black Hole with a Stellar Disk
• Extreme Mass Ratio Inspirals triggered by Massive Black Hole Binaries: from Relativistic Dynamics to Cosmological Rates