Physicist Logan Fries, a University of Connecticut Ph.D. student, recently presented groundbreaking research on the spin of nearby black holes at the 245th American Astronomical Society meeting. Fries’ study, titled “Black Hole Archaeology: Mapping the Growth History of Black Holes Across Cosmic Time,” revealed that most black holes have gained mass through accretion-driven processes rather than merger events.
Fries and his research team used data from the Sloan Digital Sky Survey Reverberation Mapping project to measure the spin of hundreds of black holes. They found that many black holes are rapidly spinning, contrary to previous expectations that they would spin down over time due to galaxy mergers.
“This is counterintuitive to what we would expect with our idea about the growth of galaxies and black holes through galaxy mergers,” Fries said. “Understanding how exactly black holes have formed and grown over cosmic time gives us valuable insights about galaxy evolution, accretion physics broadly, and cosmology.”
The researchers used a technique called “black hole archaeology” to analyze the spin of black holes, which is based on measurements taken from the innermost stable circular orbit around the black hole. By studying the spin of black holes, scientists can gain insights into their history and growth patterns.
Fries’ research has significant implications for our understanding of galaxy evolution and cosmology. The findings also contradict previous assumptions about how galaxies grow and evolve over time.
This work was supported by NSF CAREER-1945546, AST-2009539, and AST-2108668.
Source: https://today.uconn.edu/2025/01/black-hole-archaeology-understanding-how-black-holes-gained-their-mass