Gravitational interactions of stars with supermassive black hole binaries - II. Hypervelocity stars

Abstract

Supermassive black holes (SMBHs) in galactic nuclei can eject hypervelocity stars (HVSs). Using restricted three-body integrations, we study the properties of stars ejected by circular, binary SMBHs as a function of their mass ratios $q=M_2/M_1$ and separations $a$, focusing on the stellar velocity and angular distributions. We find that the ejection probability is an increasing function of $q$ and $a$, and that the mean ejected velocity scales with $q$ and $a$ similar to previous work but with modified scaling constants. Binary SMBHs tend to eject their fastest stars toward the binary orbital plane. We calculate the ejection rates as the binary SMBHs inspiral, and find that they eject stars with velocities $v_{\infty }>1000$ km/s at rates of $\sim 4\times 10^{-2}-2\times 10^{-1}$ yr${}^{-1}$ for $q=1$ ($\sim 10^{-4}-10^{-3}$ yr${}^{-1}$ for $q=0.01$) over their lifetimes, and can emit a burst of HVSs with $v_{\infty }>3000$ km/s as they coalesce. We integrate the stellar distributions over the binary SMBH inspiral and compare them to those produced by the "Hills mechanism" (in which a single SMBH ejects a star after tidally separating a binary star system), and find that $N\sim 100$ HVS velocity samples with $v_{\infty }\gtrsim 200$ km/s are needed to confidently distinguish between a binary and single SMBH origin.

arXiv comment19 pages, 16 figures

References in corpus (51)

• The M-sigma and M-L Relations in Galactic Bulges and Determinations of their Intrinsic Scatter
• REBOUND: An open-source multi-purpose N-body code for collisional dynamics
• LSST Science Book, Version 2.0
• IAS15: A fast, adaptive, high-order integrator for gravitational dynamics, accurate to machine precision over a billion orbits
• Hydrodynamical Simulations to Determine the Feeding Rate of Black Holes by the Tidal Disruption of Stars: The Importance of the Impact Parameter and Stellar Structure
• The dynamical evolution of massive black hole binaries - I. Hardening in a fixed stellar background
• Evolution of massive binary black holes
• Rates of tidal disruption of stars by massive central black holes
• Ejection of hypervelocity stars by the (binary) black hole(s) in the Galactic center
• Rates of Stellar Tidal Disruption as Probes of the Supermassive Black Hole Mass Function
• Stellar disruption by a supermassive black hole: is the light curve really proportional to $t^{-5/3}$?
• Discovery of an Unbound Hyper-Velocity Star in the Milky Way Halo
• Revised Rates of Stellar Disruption in Galactic Nuclei
• Interaction of massive black hole binaries with their stellar environment: I. Ejection of hypervelocity stars
• A Cluster of Black Holes at the Galactic Center
• HE 0437-5439 -- an unbound hyper-velocity main-sequence B-type star
• Hypervelocity Stars: Predicting the Spectrum of Ejection Velocities
• Probing the Shape of the Galactic Halo with Hyper-Velocity Stars
• Hypervelocity Stars: From the Galactic Center to the Halo
• Three-body encounters in the Galactic centre: the origin of the hypervelocity star SDSS J090745.0+024507
• Interaction of massive black hole binaries with their stellar environment: II. Loss-cone depletion and binary orbital decay
• Interaction of massive black hole binaries with their stellar environment: III. Scattering of bound stars
• Revisiting hypervelocity stars after Gaia DR2
• Runaway and hypervelocity stars in the Galactic halo: Binary rejuvenation and triple disruption
• The fine line between total and partial tidal disruption events
• A hypervelocity star with a Magellanic origin
• Tidal disruption events from supermassive black hole binaries
• Gaia and the Galactic Center Origin of Hypervelocity Stars
• Production of Hypervelocity Stars through Encounters with Stellar-Mass Black Holes in the Galactic Centre
• Binary black holes and tori in AGN I. Ejection of stars and merging of the binary
• Hypervelocity stars and the environment of Sgr A*
• Ejection of high-velocity stars from the Galactic Center by an inspiraling Intermediate-Mass Black Hole
• Tracing intermediate-mass black holes in the Galactic Centre
• Predicted Space Motions for Hypervelocity and Runaway Stars: Proper Motions and Radial Velocities for the GAIA Era
• Hypervelocity binary stars: smoking gun of massive binary black holes
• Double tidal disruptions in galactic nuclei
• Proper Motions and Trajectories for 16 Extreme Runaway and Hypervelocity Stars
• A Dipole on the Sky: Predictions for Hypervelocity Stars from the Large Magellanic Cloud
• The Velocity Distribution of Hypervelocity Stars
• Predicting the hypervelocity star population in Gaia
• Hypervelocity stars from young stellar clusters in the Galactic Centre
• Joint constraints on the Galactic dark matter halo and Galactic Centre from hypervelocity stars
• Hypervelocity Stars from the Andromeda Galaxy
• Where are the Old-Population High Velocity Stars?
• Ejection of hypervelocity binary stars by a black hole of intermediate mass orbiting Sgr A*
• Tidal disruption by extreme mass ratio binaries and application to ASASSN-15lh
• Tidal breakup of triple stars in the Galactic Centre
• Gravitational interactions of stars with supermassive black hole binaries. I. Tidal disruption events
• Stellar binaries incident on supermassive black hole binaries: implications for double tidal disruption events, calcium-rich transients, and hypervelocity stars
• The fate of close encounters between binary stars and binary supermassive black holes
• Ejection of Hyper-Velocity Stars from the Galactic Centre by Intermediate-Mass Black Holes

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• Constraints on the Galactic Centre environment from Gaia hypervelocity stars
• Constraints on the Galactic Centre environment from \textit{Gaia} hypervelocity stars III: Insights on a possible companion to Sgr A*
• Constraints on the Galactic Centre environment from Gaia hypervelocity stars II: The evolved population
• Evolution of supermassive black hole binaries and tidal disruption rates in nonspherical galactic nuclei
• Searching for clues of past binary supermassive black hole mergers in nuclear star clusters
• Deep and fast Solar System flybys: The controversial case of WD 0810-353
• Constraints on the abundance of $0.01c$ stellar engines in the Milky Way
• A Recent Supermassive Black Hole Binary in the Galactic Center Unveiled by the Hypervelocity Stars
• The Type Ia Supernova 2021hem: A 2003fg-like Event in an Apparently Hostless Environment
• Using the Hills Mechanism to Generate Repeating Partial Tidal Disruption Events and ASASSN-14ko
• Taking apart the dynamical clock. Fat-tailed dynamical kicks shape the blue-straggler star bimodality