Video: Turning Black Holes into Dark Matter Labs
A new computer simulation tracking dark matter particles in the extreme gravity of a black hole shows that strong, potentially observable gamma-ray light can be produced.
Detecting this emission would provide astronomers with a new tool for understanding both black holes and the nature of dark matter, an elusive substance accounting for most of the mass of the universe that neither reflects, absorbs nor emits light.
Jeremy Schnittman, an astrophysicist at NASA’s Goddard Space Flight Center, developed a computer simulation to follow the orbits of hundreds of millions of dark matter particles, as well as the gamma rays produced when they collide, in the vicinity of a black hole. He found that some gamma rays escaped with energies far exceeding what had been previously regarded as theoretical limits.
In the simulation, dark matter takes the form of Weakly Interacting Massive Particles, or WIMPS, now widely regarded as the leading candidate class. In this model, WIMPs that crash into other WIMPs mutually annihilate and convert into gamma rays, the most energetic form of light. But these collisions are extremely rare under normal circumstances.
Over the past few years, theorists have turned to black holes as dark matter concentrators, where WIMPs can be forced together in a way that increases both the rate and energies of collisions. The concept is a variant of the Penrose process, first identified in 1969 by British astrophysicist Sir Roger Penrose as a mechanism for extracting energy from a spinning black hole. The faster it spins, the greater the potential energy gain.
Schnittman’s model tracks the positions and properties of hundreds of millions of randomly distributed particles as they collide and annihilate near a black hole. The new model reveals processes that produce gamma rays with much higher energies, as well as a better likelihood of escape and detection, than ever thought possible. He identified previously unrecognized trajectories where collisions produce gamma rays with a peak energy 14 times the rest mass of the annihilating particles.
The simulation tells astronomers that there is an astrophysically interesting signal they may be able to detect as gamma-ray telescopes improve.
