We study the long-term evolution of massive black hole binaries (MBHBs) at the centers of galaxies using detailed scattering experiments to solve the full three-body problem. Ambient stars drawn from an isotropic Maxwellian distribution unbound to the binary are ejected by the gravitational slingshot. We construct a minimal, hybrid model for the depletion of the loss cone and the orbital decay of the binary and show that secondary slingshots - stars returning on small-impact parameter orbits to have a second superelastic scattering with the MBHB - may considerably help the shrinking of the pair in the case of large binary mass ratios. In the absence of loss cone refilling by two-body relaxation or other processes, the mass ejected before the stalling of a MBHB is half the binary reduced mass. About 50% of the ejected stars are expelled in a "burst" lasting ∼ 104 yr M61/4, where M6 is the binary mass in units of 106 M ⊙. The loss cone is completely emptied in a few bulge crossing timescales, ∼ 107 yr M61/4. Even in the absence of two-body relaxation or gas dynamical processes, unequal mass and/or eccentric binaries with M6 ≳ 0.1 can shrink to the gravitational wave emission regime in less than a Hubble time and are therefore "safe" targets for the planned Laser Interferometer Space Antenna.

Sesana, A., Haardt, F., Madau, P. (2007). Interaction of massive black hole binaries with their stellar environment. II. Loss cone depletion and binary orbital decay. THE ASTROPHYSICAL JOURNAL, 660(1 I), 546-555 [10.1086/513016].

Interaction of massive black hole binaries with their stellar environment. II. Loss cone depletion and binary orbital decay

Sesana, A;Madau, P
2007

Abstract

We study the long-term evolution of massive black hole binaries (MBHBs) at the centers of galaxies using detailed scattering experiments to solve the full three-body problem. Ambient stars drawn from an isotropic Maxwellian distribution unbound to the binary are ejected by the gravitational slingshot. We construct a minimal, hybrid model for the depletion of the loss cone and the orbital decay of the binary and show that secondary slingshots - stars returning on small-impact parameter orbits to have a second superelastic scattering with the MBHB - may considerably help the shrinking of the pair in the case of large binary mass ratios. In the absence of loss cone refilling by two-body relaxation or other processes, the mass ejected before the stalling of a MBHB is half the binary reduced mass. About 50% of the ejected stars are expelled in a "burst" lasting ∼ 104 yr M61/4, where M6 is the binary mass in units of 106 M ⊙. The loss cone is completely emptied in a few bulge crossing timescales, ∼ 107 yr M61/4. Even in the absence of two-body relaxation or gas dynamical processes, unequal mass and/or eccentric binaries with M6 ≳ 0.1 can shrink to the gravitational wave emission regime in less than a Hubble time and are therefore "safe" targets for the planned Laser Interferometer Space Antenna.
Articolo in rivista - Articolo scientifico
Black hole physics; Methods: numerical; Stellar dynamics;
English
2007
660
1 I
546
555
none
Sesana, A., Haardt, F., Madau, P. (2007). Interaction of massive black hole binaries with their stellar environment. II. Loss cone depletion and binary orbital decay. THE ASTROPHYSICAL JOURNAL, 660(1 I), 546-555 [10.1086/513016].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/453172
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