Some Black Holes Which Attempt to Regrow Hair Become Bald Again

“In addition to a maximal value of charge, there is also a limit for how fast a black hole can spin. Black holes that spin at the maximal allowed rate are therefore also called extreme black holes. We describe both maximally charged and maximally spinning black holes by the name extreme black holes, as there are many similarities between the two. The new hair was originally found for a very useful toy model for black holes, specifically black holes that are spherically symmetric and electrically charged. But black holes in reality are neither. Instead, we wanted to find out if this hair can be found also for spinning black holes,” said Burko. “In the movie Interstellar the monster black hole is nearly extreme. We wanted to see if Gargantua has hair.”

The team used very intensive numerical simulations to generate their results. The simulations involved using dozens of the highest-end Nvidia graphics-processing-units (GPUs) with over 5,000 cores each, in parallel. “Each of these GPUs can perform as many as 7 trillion calculations per second; however, even with such computational capacity the simulations took many weeks to complete” said Khanna.

The team showed that for the nearly extreme spinning black holes the hair is a transient behavior. At intermediate times nearly extreme black holes behave like extreme black holes would, but at late times they behave like regular, non-extreme black holes. “Nearly extreme black holes can pretend that they are extreme for only so long. But eventually their non-extremality becomes manifest,” Burko summarized. “Nearly extreme black holes that attempt to regrow hair will lose it and become bald again.” The team also discusses the observational features, e.g., with gravitational waves observatories such as LIGO/VIRGO or LISA, of the smoking-gun detection of nearly extreme black holes.

The research was partially funded by the National Science Foundation and the Office of Naval Research. Computational resources of UMass Dartmouth’s Center for Scientific Computing & Visualization Research (CSCVR) were utilized for the research work. The CSCVR promotes the mission of UMass Dartmouth by providing undergraduate and graduate students with high quality discovery-based educational experiences that transcend the traditional boundaries of academic field or department, and foster collaborative research in the computational sciences within the University and with researchers at other universities, National Labs, and industry. Khanna serves as the Director of the Center.

This open-access paper was published Friday, 11/15/2019 as PHYSICAL REVIEW RESEARCH 1, 033106 (2019), DOI:10.1103/PhysRevResearch.1.033106.

Contacts and sources:
Lucas Franca
Theiss Research