Circumbinary Disk Movies

Movies Corresponding to Figure 10 of "A Transition in Circumbinary Accretion Discs at a Binary Mass Ratio of 1:25", Published in MNRAS. On the arXiv




Movies From "Accretion into the Central Cavity of a Circumbinary Gas Disc"

Zoltan Haiman, Andrew MacFadyen and I are simulating accretion disks around massive black hole binaries in the (non gravitational-wave dominated) inspiral regime. In 2013 we published a paper which explores how such disks respond to circular binaries of different mass ratios, q = (Mass of secondary)/(Mass of primary). In this study we are chiefly interested in the mass accretion rate towards the holes. We find that three main variability timescales appear in the simulated accretion rates as a function of q. Two of these timescales (1x and 2x the binary orbital period) are set strictly by the binary orbital parameters. A longer variability period (~3-8x the binary orbital period) depends on disk parameters. Knowledge of the two accretion timescales set by the binary may aid in identifying binaries in galactic nuclei. If a binary in the inspiral stage is identified in future surveys (since writing the future is now!), identification of such a third, longer timescale could provide clues to the conditions present in a putative disk surrounding the holes.

The movies below elaborate on Figure 3 of the paper and can be played by clicking on the desired density profile snapshot. Each depicts the inner 6 r/a of the disk (inner 6% in radius of the simulated disk) where a is the binary separation. The inner solid circle denotes the inner edge of the simulation domain and is where we measure accretion rates. The larger dashed circle is set at r = 2.08a to guide the eye. The first two movies, from left to right, are for an equal mass (q=1.0) binary with the first having a viscosity parameter of alpha=0.01 and the second having a viscosity parameter of alpha=0.04. The subsequent movies have mass ratios decreasing from left to right, top to bottom: q=0.5, q=0.25, q=0.1, q=0.01; all with viscosity parameter alpha=0.01.

Movies from Big black hole, little neutron star: Magnetic dipole fields in the Rindler spacetime

Janna Levin, myself, and collaborators Norm Murray and Larry Price have a paper titled: "Bright transients from strongly-magnetized neutron star-black hole mergers" on the observability of NS-BH mergers based on the BH-battery mechanism described in the above paper. Figure 1 from this paper was featured in PRD's Kaleidoscope.