Mergers of black hole binaries driven by misaligned circumbinary discs. (arXiv:2311.10160v1 [astro-ph.HE])

<a href="http://arxiv.org/find/astro-ph/1/au:+Martin_R/0/1/0/all/0/1">Rebecca G. Martin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lepp_S/0/1/0/all/0/1">Stephen Lepp</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhang_B/0/1/0/all/0/1">Bing Zhang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nixon_C/0/1/0/all/0/1">C. J. Nixon</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Childs_A/0/1/0/all/0/1">Anna C. Childs</a>

With hydrodynamical simulations we examine the evolution of a highly

misaligned circumbinary disc around a black hole binary including the effects

of general relativity. We show that a disc mass of just a few percent of the

binary mass can significantly increase the binary eccentricity through

von-Zeipel–Kozai-Lidov (ZKL) like oscillations provided that the disc lifetime

is longer than the ZKL oscillation timescale. The disc begins as a relatively

narrow ring of material far from the binary and spreads radially. When the

binary becomes highly eccentric, disc breaking forms an inner disc ring that

quickly aligns to polar. The polar ring drives fast retrograde apsidal

precession of the binary that weakens the ZKL effect. This allows the binary

eccentricity to remain at a high level and may significantly shorten the black

hole merger time. The mechanism requires the initial disc inclination relative

to the binary to be closer to retrograde than to prograde.

With hydrodynamical simulations we examine the evolution of a highly

misaligned circumbinary disc around a black hole binary including the effects

of general relativity. We show that a disc mass of just a few percent of the

binary mass can significantly increase the binary eccentricity through

von-Zeipel–Kozai-Lidov (ZKL) like oscillations provided that the disc lifetime

is longer than the ZKL oscillation timescale. The disc begins as a relatively

narrow ring of material far from the binary and spreads radially. When the

binary becomes highly eccentric, disc breaking forms an inner disc ring that

quickly aligns to polar. The polar ring drives fast retrograde apsidal

precession of the binary that weakens the ZKL effect. This allows the binary

eccentricity to remain at a high level and may significantly shorten the black

hole merger time. The mechanism requires the initial disc inclination relative

to the binary to be closer to retrograde than to prograde.

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