For the first time, scientists believe they have detected a merger of two
black holes with eccentric orbits. According to a paper published in Nature
Astronomy by researchers from Rochester Institute of Technology's Center for
Computational Relativity and Gravitation and the University of Florida, this
can help explain how some of the black hole mergers detected by LIGO
Scientific Collaboration and the Virgo Collaboration are much heavier than
previously thought possible.
Eccentric orbits are a sign that black holes could be repeatedly gobbling up
others during chance encounters in areas densely populated with black holes
such as galactic nuclei. The scientists studied the most massive
gravitational wave binary observed to date, GW190521, to determine if the
merger had eccentric orbits.
"The estimated masses of the black holes are more than 70 times the size of
our sun each, placing them well above the estimated maximum mass predicted
currently by stellar evolution theory," said Carlos Lousto, a professor in
the School of Mathematical Sciences and a member of the CCRG. "This makes an
interesting case to study as a second generation binary black hole system
and opens up to new possibilities of formation scenarios of black holes in
dense star clusters."
A team of RIT researchers including Lousto, Research Associate James Healy,
Jacob Lange, Ph.D. (astrophysical sciences and technology), Professor and
CCRG Director Manuela Campanelli, Associate Professor Richard O'Shaughnessy,
and collaborators from the University of Florida formed to give a fresh look
at the data to see if the black holes had highly eccentric orbits before
they merged. They found the merger is best explained by a high-eccentricity,
precessing model. To achieve this, the team performed hundreds of new full
numerical simulations in local and national lab supercomputers, taking
nearly a year to complete.
"This represents a major advancement in our understanding of how black holes
merge," said Campanelli. "Through our sophisticated supercomputer
simulations and the wealth of new data provided by LIGO and Virgo's rapidly
advancing detectors, we are making new discoveries about the universe at
astonishing rates."
An extension of this analysis by the same RIT and UFL team used a possible
electromagnetic counterpart observed by the Zwicky Transient Facility to
compute independently the cosmological Hubble constant with GW150521 as an
eccentric binary black hole merger. They found excellent agreement with the
expected values and recently published the work in the Astrophysical
Journal.
References:
V. Gayathri et al, Eccentricity estimate for black hole mergers with
numerical relativity simulations, Nature Astronomy (2022).
DOI: 10.1038/s41550-021-01568-w
V. Gayathri et al, Measuring the Hubble Constant with GW190521 as an
Eccentric black hole Merger and Its Potential Electromagnetic Counterpart,
The Astrophysical Journal (2021).
DOI: 10.3847/2041-8213/abe388
Tags:
Space & Astrophysics