The binary black hole explorer: on-the-fly visualizations of precessing binary black holes

TL;DR

BinaryBHexp is presented, a tool that makes use of surrogate models of numerical simulations to generate on-the-fly interactive visualizations of precessing binary black holes that can be generated in a few seconds, and at any point in the 7-dimensional parameter space of the underlying surrogate models.

Abstract

Binary black hole mergers are of great interest to the astrophysics community, not least because of their promise to test general relativity in the highly dynamic, strong field regime. Detections of gravitational waves from these sources by LIGO and Virgo have garnered widespread media and public attention. Among these sources, precessing systems (with misaligned black-hole spin/orbital angular momentum) are of particular interest because of the rich dynamics they offer. However, these systems are, in turn, more complex compared to nonprecessing systems, making them harder to model or develop intuition about. Visualizations of numerical simulations of precessing systems provide a means to understand and gain insights about these systems. However, since these simulations are very expensive, they can only be performed at a small number of points in parameter space. We present binaryBHexp, a tool that makes use of surrogate models of numerical simulations to generate on-the-fly interactive visualizations of precessing binary black holes. These visualizations can be generated in a few seconds, and at any point in the 7-dimensional parameter space of the underlying surrogate models. With illustrative examples, we demonstrate how this tool can be used to learn about precessing binary black hole systems.

Figures (7)

• Figure 1: Snapshots during the inspiral (top-left), post-ringdown (top-right), and intermediate (bottom) stages of a precessing binary BH evolution. Each BH horizon is represented by an oblate spheroid. The arrows on the BHs indicate the spin vectors; the larger the spin the longer the arrow. The arrow centered at the origin indicates the orbital angular momentum. On the bottom plane, we show the plus polarization of GWs, as seen by an observer at each point. Red (blue) colors indicate positive (negative) values. Notice the quadrupolar nature of the emitted waves. The subplots at the bottom of each panel show GW plus and cross polarizations, as seen by a far-away observer viewing from the camera viewing angle. The time to the peak of the waveform amplitude is indicated in the figure text as well as the slider in the bottom subplots. This animation is available at https://vijayvarma392.github.io/binaryBHexp/#prec_bbh.
• Figure 2: Example of the real part of the $(\ell=2,m=1)$ spin-weighted spherical harmonic mode (see Sec. \ref{['subsec:gw_methods']}) of the GW for a precessing black hole binary, in the inertial (top) and coprecessing (bottom) frames. $t=0$ corresponds to the peak of the waveform amplitude.
• Figure 3: Comparison of the coordinate trajectories of the heavier BH for a precessing binary BH, between NR, and our approximation using NRSur7dq2 and PN. $t=0$ corresponds to the peak of the waveform amplitude. The mass ratio, and spins at $t=-4500M$ are shown at the top of the plot.
• Figure 4: Visualization of a precessing binary black hole system where we also vary the camera viewing angle during the inspiral. Notice how the waveform structure in the bottom subplots changes based on whether the viewing angle is edge-on (top-left), intermediate (top-right), or face-on (bottom). This animation is available at https://vijayvarma392.github.io/binaryBHexp/#prec_bbh_rotating_camera.
• Figure 5: Visualization of the orbital hang-up effect. We show three nonprecessing systems with equal masses, and equal spins. In the left (right) column, both spins are aligned (anti-aligned) with $\bm{L}$, with magnitude 0.8. The middle column shows a nonspinning binary. All three systems start at an orbital frequency of $0.018~\text{rad}/M$. Due to orbital hang-up effect, the length of the waveform is longer (shorter) for the aligned case compared to the nonspinning case (see the bottom subplots showing the waveform). Time flows downwards (labeled at the left), and each row corresponds to a fixed time since the start of the animation. This animation is available at https://vijayvarma392.github.io/binaryBHexp/#hangup.