Ejection of Hypervelocity Stars by the (Binary) Black Hole in the Galactic Center

By Qingjuan Yu, S. Tremaine. 2003

315 citations recorded by the source corpus.

We study three processes that eject hypervelocity (>103 km s-1) stars from the Galactic center: (1) close encounters of two single stars, (2) tidal breakup of binary stars by the central black hole, as originally proposed by Hills, and (3) three-body interactions between a star and a binary black hole (BBH). Mechanism 1 expels hypervelocity stars to the solar radius, R0 = 8 kpc, at a negligible rate, ~10-11 yr-1. Mechanism 2 expels hypervelocity stars at a rate ~10-5(η/0.1) yr-1, where η is the fraction of stars in binaries with semimajor axis ab ≲ 0.3 AU. For solar mass stars, the corresponding number of hypervelocity stars within the solar radius is ~60(η/0.1)(ab/0.1 AU)1/2. For mechanism 3, Sgr A* is assumed to be one component of a BBH. We constrain the allowed parameter space (semimajor axis, mass ratio) of the BBH. In the allowed region (for example, a semimajor axis of 0.5 × 10-3 pc and a mass ratio of 0.01), the rate of ejection of hypervelocity stars can be as large as ~10-4 yr-1, and the expected number of hypervelocity stars within the solar radius can be as large as ~103. Hypervelocity stars may be detectable by the next generation of large-scale optical surveys.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/7d6f52da3435beba87389f496e48f0c1b5a69ba3

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Citations in the corpus

The Progenitors of Type Ia Supernovae (2012, background): “It has been suggested that such HVSs can be formed by the tidal disruption of a binary through interaction with the super-massive black hole (SMBH) at the Galactic center (GC) (Hills, 1988; Yu and Tremaine, 2003; Zhang et al., 2010).”
Massive Black Hole Binary Evolution (2004, background): “…reflex motion of AGN photocenters due to orbital motion of the jet-producing SBHs [219]; measurement of periodic shifts in pulsar arrival times due to passage of gravitational waves from binary SBHs [123]; and, of course, direct detection of gravitational waves by space-based interferometers.”
The RAVE Survey: Constraining the Local Galactic Escape Speed (2006, background): “However, Yu & Tremaine (2003) found that the numbers of hypervelocity stars produced would be about 10−5 yr−1 (see also Perets, Hopman & Alexander 2006).”
Stellar Dynamics and Stellar Phenomena Near a Massive Black Hole (2017, background): “(Hills 1988; Yu & Tremaine 2003), which can exceed the escape velocity from the host galaxy (Sec.”
Merging Binaries in the Galactic Center: The eccentric Kozai-Lidov mechanism with stellar evolution (2016, background): “…GC (Alexander & Hopman 2009)1, the stellar number density (e.g., Alexander & Pfuhl 2014; Prodan et al. 2015), the S-star cluster population (e.g., Antonini & Merritt 2013), as well as hypervelocity stars (e.g., Hills 1988; Yu & Tremaine 2003; Ginsburg & Loeb 2007; Perets et al. 2009; Perets 2009).”
Mass Deficits, Stalling Radii, and the Merger Histories of Elliptical Galaxies (2006, background): “The short nuclear relaxation time would also accelerate the hardening of a massive binary by ensuring that stars were scattered into its sphere of influence (Yu & Tremaine 2003).”
Massive Perturber-driven Interactions between Stars and a Massive Black Hole (2006, methodology): “However, MPs will enhance by factors of 10–1000 the tidal disruption rate of infalling binaries, which result in the capture of one of the stars on a tight orbit around the MBH, and the ejection at high velocity of the other star (Hills 1991, 1992; Yu & Tremaine 2003).”
US 708 – an unbound hyper-velocity subluminous O star (2005, background): “Yu & Tremaine (2003) confirmed this and predicted production rates of up to 10−5 HVS/yr.”
GIANT GAMMA-RAY BUBBLES FROM FERMI-LAT: ACTIVE GALACTIC NUCLEUS ACTIVITY OR BIPOLAR GALACTIC WIND? (2010, background): “These HVSs distributed in the Galactic halo are believed to originate from the GC involving interactions of stars with the MBH (Hills 1988; Yu & Tremaine 2003).”
Interaction of Massive Black Hole Binaries with Their Stellar Environment. I. Ejection of Hypervelocity Stars (2006, methodology): “Assuming SgrA∗ to be one component of a MBHB, Yu & Tremaine (2003) estimated the number of HVSs expected within the solar radius to be ∼ 103.”
Supermassive black hole binaries in gaseous and stellar circumnuclear discs: orbital dynamics and gas accretion (2006, background): “In dry mergers, binary MBHs can erode the inner stellar cusp (Milosavljevic et al. 2002), creating a population of hyper– velocity stars in galactic halos (Yu & Tremaine 2003; Brown et al. 2006).”
The Proper Motion of Sagittarius A*. II. The Mass of Sagittarius A* (2004, background): “The possibility that a binary black hole exists in the center of the Galaxy has been discussed by Hansen & Milosavljević (2003) and Yu & Tremaine (2003).”
Stellar Remnants in Galactic Nuclei: Mass Segregation (2006, background): “This process is of great interest by itself, both as a way of creating ‘‘hypervelocity stars’’ and as a way of depositing a star into a tight orbit around the MBH (Hills 1988; Yu & Tremaine 2003; Gualandris et al. 2005b; Miller et al. 2005; Pfahl 2005).”