Self-lensing flares from black hole binaries I: general-relativistic ray tracing of black hole binaries

Abstract

The self-lensing of a massive black hole binary (MBHB), which occurs when the two BHs are aligned close to the line of sight, is expected to produce periodic, short-duration flares. Here we study the shapes of self-lensing flares (SLFs) via general-relativistic ray tracing in a superimposed binary BH metric, in which the emission is generated by geometrically thin accretion flows around each component. The suite of models covers eccentric binary orbits, black hole spins, unequal mass binaries, and different emission model geometries. We explore the above parameter space, and report how the light curves change as a function of, e.g., binary separation, inclination, and eccentricity. We also compare our light curves to those in the microlensing approximation, and show how strong deflections, as well as time-delay effects, change the size and shape of the SLF. If gravitational waves (GWs) from the inspiraling MBHB are observed by LISA, SLFs can help securely identify the source and localizing it on the sky, and to constrain the graviton mass by comparing the phasing of the SLFs and the GWs. Additionally, when these systems are viewed edge-on the SLF shows a distinct dip that can be directly correlated with the BH shadow size. This opens a new way to measure BH shadow sizes in systems that are unresolvable by current VLBI facilities.

16 pages, 15 figures, 1 table. Submitted to journal

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Cited by in corpus (14)

• Cosmology with the Laser Interferometer Space Antenna
• Electromagnetic Counterparts to Massive Black Hole Mergers
• The Decoupling of Binaries from Their Circumbinary Disks
• Self-lensing flares from black hole binaries II: observing black hole shadows via light-curve tomography
• Comparison of Polarized Radiative Transfer Codes used by the EHT Collaboration
• Disk induced binary precession: Implications for dynamics and multi-messenger observations of black hole binaries
• Blacklight: A General-Relativistic Ray-Tracing and Analysis Tool
• ESPRESSO reveals a single but perturbed broad-line region in the supermassive black hole binary candidate PG 1302-102
• Resolving the Vicinity of Supermassive Black Holes with Gravitational Microlensing
• A fast test for the identification and confirmation of massive black hole binaries
• Impact of a binary black hole on its outer circumbinary disc
• Prospects for ray-tracing light intensity and polarization in models of accreting compact objects using a GPU
• Microlensing Black Hole Shadows
• Sculpting the outer edge of accretion disks in pre-circumbinary binary black hole systems