Equilibrium eccentricity of accreting binaries. (arXiv:2010.09707v2 [astro-ph.HE] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Zrake_J/0/1/0/all/0/1">Jonathan Zrake</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tiede_C/0/1/0/all/0/1">Christopher Tiede</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+MacFadyen_A/0/1/0/all/0/1">Andrew MacFadyen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Haiman_Z/0/1/0/all/0/1">Zoltán Haiman</a>
Using high-resolution hydrodynamics simulations, we show that equal-mass
binaries accreting from a circumbinary disk evolve toward an orbital
eccentricity of $e simeq 0.45$, unless they are initialized on a nearly
circular orbit with $e lesssim 0.08$, in which case they further circularize.
The implied bi-modal eccentricity distribution resembles that seen in post-AGB
stellar binaries. Large accretion spikes around periapse impart a tell-tale,
quasi-periodic, bursty signature on the light curves of eccentric binaries. We
predict that intermediate-mass and massive black hole binaries at $z lesssim
10$ entering the emph{LISA} band will have measurable eccentricities in the
range $e simeq 10^{-3} – 10^{-2}$, if they have experienced a gas-driven
phase. On the other hand, GW190521 would have entered the LIGO/Virgo band with
undetectable eccentricity $sim 10^{-6}$ if it had been driven into the
gravitational wave regime by a gas disk.
Using high-resolution hydrodynamics simulations, we show that equal-mass
binaries accreting from a circumbinary disk evolve toward an orbital
eccentricity of $e simeq 0.45$, unless they are initialized on a nearly
circular orbit with $e lesssim 0.08$, in which case they further circularize.
The implied bi-modal eccentricity distribution resembles that seen in post-AGB
stellar binaries. Large accretion spikes around periapse impart a tell-tale,
quasi-periodic, bursty signature on the light curves of eccentric binaries. We
predict that intermediate-mass and massive black hole binaries at $z lesssim
10$ entering the emph{LISA} band will have measurable eccentricities in the
range $e simeq 10^{-3} – 10^{-2}$, if they have experienced a gas-driven
phase. On the other hand, GW190521 would have entered the LIGO/Virgo band with
undetectable eccentricity $sim 10^{-6}$ if it had been driven into the
gravitational wave regime by a gas disk.
http://arxiv.org/icons/sfx.gif
