However, Varma and collaborators applied two data-gathering hacks in order to detect these first hints.įirst, Varma applied computer modeling based on simulations of black holes. It was thought that LIGO and Virgo gravitational wave detectors were not sensitive enough to pick up evidence of spin-orbit resonances. "These are special configurations where the spins directions in the orbital plane are either parallel or anti-parallel." "If the supernova recoils are large enough, the binary can end up in a spin-orbit resonance," Varma said. If the supernova emission is not symmetric in all directions, the black hole gets a recoil velocity at birth, which is similar to the recoil of a fired gun. Spin-orbit resonances can occur in precessing binaries, but this depends on the nature of the supernova mechanism that produces the black holes from their stellar progenitors, Varma said. "When the spins are tilted with respect to the orbital angular momentum, the orbit precesses like a top that is spinning along a tilted axis," Varma said. But other binary black holes have spins tilted with respect to the orbital angular momentum, setting off an intricate interaction called precession. Some binary black hole spins are aligned along or opposite the orbital angular momentum, leading to a "bland" merger on a fixed plane. When two such black holes orbit each other in a binary, their spins interact with the orbit.īinary black holes lose energy to gravitational waves, causing the black holes to move toward each other and eventually merge, Varma said. This work shows that if we analyze the data cleverly, we are much closer to testing this prediction of General Relativity than we thought we were."īlack holes typically rotate (spin) because they form from dying stars that spin themselves, Varma said. "In the black hole systems that Vijay is studying, the resonance is predicted to occur between the spin motion of the black holes and their orbital motion, and leaves an imprint on the gravitational waves produced. Bethe Professor of Physics (A&S), Varma's faculty mentor at Cornell. They occur when two processes in a system occur at specially related frequencies," said Saul Teukolsky, the Hans A. "Resonance effects are ubiquitous in physical systems. Collaborators on this work include Syliva Biscoveanu, Maximiliano Isi and Salvatore Vitale from the Massachusetts Institute of Technology, and Will Farr from the Flatiron Institute. Varma conducted much of this research while a Klarman Fellow he is now a Marie Curie fellow at the Max Planck Institute for Gravitational Physics. More observations are needed to confirm these tendencies, Varma said. In "Hints of Spin-Orbit Resonances in the Binary Black Hole Population," published January 19 in Physical Review Letters, Varma and collaborators report that the two black holes' spins, when projected onto the orbital plane, tend to be anti-parallel to each other, which can be a signature of spin- orbit resonances. The rate at which a black hole spins reveals a lot about its history, Varma said: For black holes arranged in an interactive pair, called a binary, the direction of each black hole's spin is also revelatory, especially in relation to one another. "We find the first 'hints' of the resonances in gravitational wave data from LIGO and Virgo." A former Klarman Postdoctoral Fellow in the College of Arts & Sciences (A&S), Varma analyzes gravitational waves detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Virgo gravitational wave detector in order to learn more about binary black holes. "These resonances were predicted over a decade ago using Einstein's theory of general relativity," said astrophysicist Vijay Varma.
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