Resolving the relative influence of strong field spacetime dynamics and MHD on circumbinary disk physics

Abstract

In this paper we evolve magnetized and unmagnetized circumbinary accretion disks around supermassive black hole binaries in the relativistic regime. We use a post-Newtonian expansion to construct an analytical spacetime and determine how the order of the post-Newtonian (PN) expansion affects the dynamics of the gas. We find very small differences in the late-time bulk dynamics of non-magnetized hydrodynamic evolutions between the two spacetimes down to separations of approximately $40GM/c^2$ where $M$ is the total mass of the binary. For smaller separations, the differences due to PN-order become comparable to differences caused by using initial data further from equilibrium. For magnetized gas, MHD stresses, which drives the accretion dynamics, tends to mask all higher order PN effects even at separations of $20GM/c^2$, leading to essentially the same observed electromagnetic luminosity. This implies that our calculations of the EM signal may be robust down to small binary separations. Our investigation is the first to demonstrate how the level of PN accuracy affects a circumbinary disk's evolution and informs us of the range in separation within which to trust the PN approximation for this kind of study. We also address the influence the initial conditions and binary separation have on simulation predictions.

14 pages, 12 figures. v2: matches published version in PRD

References in corpus (6)

• Binary Black-Hole Mergers in Magnetized Disks: Simulations in Full General Relativity
• A close-pair binary in a distant triple supermassive black-hole system
• Gravitational recoil: signatures on the massive black hole population
• General Relativistic Simulations of Magnetized Plasmas around Merging Supermassive Black Holes
• Binary black hole mergers in gaseous disks: Simulations in general relativity
• Retaining Black Holes with Very Large Recoil Velocities

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• Perturbative extraction of gravitational waveforms generated with Numerical Relativity
• Mini-disk accretion onto spinning black hole binaries: quasi-periodicities and outflows
• Electromagnetic Signatures from Supermassive Binary Black Holes Approaching Merger
• Circumbinary Disk Accretion into Spinning Black Hole Binaries
• Superposed metric for spinning black hole binaries approaching merger
• General Relativistic Magnetohydrodynamic Simulations of Accretion Disks Around Tilted Binary Black Holes of Unequal Mass
• Final stage of merging binaries of supermassive black holes: observational signatures
• Relativistic gas accretion onto supermassive black Hole binaries from inspiral through merger
• Impact of a binary black hole on its outer circumbinary disc
• Evolution of circumbinary accretion disk around supermassive binary black hole: post-Newtonian hydrodynamics versus Newtonian hydrodynamics
• Sculpting the outer edge of accretion disks in pre-circumbinary binary black hole systems
• Misaligned Spinning Binary Black Hole Mergers in Hot Magnetized Plasma