Chaotic, Three-body Orbit

A star (red point) approaches a binary supermassive black hole system (two black points) with a mass ratio of 0.2. When far away the star approaches the binary center of mass on an approximately parabolic orbit, but its motion becomes highly chaotic as it starts to experience the individual gravitational potentials of each black hole. After being temporarily bound to the binary for a number of binary orbits, the star is kicked out of the system on a hyperbolic trajectory.

Tidal Disruption by a SMBH Binary

This movie shows how a star is disrupted by a binary supermassive black hole system, with the left-hand panel showing the projection onto the binary orbital plane, the right-hand panel out of the plane. Here the primary has a mass of one million Solar masses, the binary mass ratio is q = 0.2, and the separation of the binary is roughly 0.1 mpc (or about 50 AU). The colors scale with the column density of the disrupted debris, with brighter (darker) colors indicating denser (less dense) regions.

Disk Formation

Here we see how a disk of tidally-disrupted debris forms around the primary SMBH following the tidal disruption of a star. In this case, a number of distinct accretion disks form a discrete times, with those disks having inclinations relative to one another and the binary orbital plane. Over time, the viscous interaction between the disks causes their inclination angles to change.

Long Term Evolution

The same as "Tidal Disruption by a SMBH Binary," but run on for nearly six binary orbits. By the end, two accretion disks have formed around the primary and secondary SMBHs.

Tidal Disruption by an Extreme Mass Ratio Binary

Here the mass ratio of the binary is 0.005 and the mass of the secondary is 500,000 times the mass of the Sun (making the primary too massive to tidally disrupt a Solar-type star). The inset on the top right shows a zoom-in of the accretion disk that forms around the secondary, while the inset on the bottom right shows the accretion rate onto the secondary. We see, around 90 days post-disruption, that the accretion rate and disk morphology change drastically, which is a predictable aspect of this configuration. Such a model could be applicable to the superluminous supernovae ASASSN-15lh.

Spherically-symmetric Collapse

The infall of a spherically-symmetric, pressureless cloud under its own self-gravity. The different circles illustrate different shells of mass (colors are just for clarity). At a time of pi/2 ~ 1.57, the center forms a point mass (i.e., a singularity), which is denoted by the black circle. The radius of the circle increases in proportion to its mass, which grows in time as it accretes the remainder of the cloud.

Magnetic Field Evolution

The evolution of the magnetic field lines in a collapsing cloud (see movie above) with a small amount of initial rotation about the z-axis. Here the field is initially uniform in the z-direction, and the differential rotation induced by the collapse twists the field lines in the azimuthal direction, generating a toroidal field. At a time of pi/2 ~ 1.57, the point mass forms, and the field lines become more radial as matter "drags" the field into the central region.

Magnetic Field Evolution (Closeup)

Same as above, but zoomed in on the innermost collection of field lines. Here it is evident that the field lines are tightly wound around the rotation axis, forming a coil-like structure, before unwinding and unfolding as the point mass forms.