by Riko Seibo
Tokyo, Japan (SPX) Aug 05, 2025
Black holes, the most gravitationally extreme objects in the universe, emit space-time ripples called quasinormal modes when disturbed - vibrations that can be detected as gravitational waves. These signals offer critical insight into a black hole's mass and structure, but precisely modeling the rapidly fading ones has remained elusive.
In a breakthrough study, Kyoto University researchers have applied a sophisticated mathematical technique - known as exact Wentzel-Kramers-Brillouin (WKB) analysis - to resolve this challenge. Traditionally developed in mathematical circles, exact WKB is still emerging in physics applications, especially in black hole research.
"The foundations of the exact WKB method were largely developed by Japanese mathematicians. As a researcher from Japan, I have always found this field intellectually and culturally familiar," explained corresponding author Taiga Miyachi.
By extending their wave analysis into the complex number domain, the team could trace elusive patterns and structures around black holes. Central to their method was the inclusion of intricate Stokes curves - spiraling mathematical features previously overlooked - which mark where wave behavior transitions sharply.
This approach enabled precise tracking of how quasinormal modes decay, revealing a surprisingly rich geometry in black hole environments. "We were surprised at how complex and beautiful the underlying structure of these vibrations turned out to be. We found spiraling patterns in our mathematical analysis that had been missed before, and these turned out to be key in understanding the full picture of quasinormal modes," Miyachi noted.
Their findings offer a more reliable framework for interpreting gravitational wave data and open new pathways for applying mathematical physics to general relativity. The researchers now aim to adapt their methods to study rotating black holes and probe quantum gravity scenarios.
Research Report:Path to an exact WKB analysis of black hole quasinormal modes
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