Astronomers using the MeerKAT Pulsar Timing Array, an international experiment that uses the MeerKAT Radio Telescope in South Africa, have uncovered further evidence of gravitational wave signals originating from merging supermassive black holes.
Miles et al. created the most detailed maps of gravitational waves across the Universe to date. Image credit: Carl Knox / OzGrav / Swinburne University of Technology / South African Radio Astronomy Observatory.
“Our research opens new pathways for understanding the Universe that we live in,” said Dr. Matt Miles, an astronomer at the ARC Centre of Excellence for Gravitational Wave Discovery (OzGRav) and Swinburne University of Technology.
“Studying the background lets us tune into the echoes of cosmic events across billions of years. It reveals how galaxies, and the Universe itself, have evolved over time.”
The MeerKAT Pulsar Timing Array observes pulsars — rapidly spinning neutron stars — and times them to nanosecond precision.
Pulsars serve as natural clocks, and their steady pulses allow scientists to detect minuscule changes caused by passing gravitational waves.
This galactic-scale detector has provided an opportunity to map gravitational waves across the sky, revealing patterns and strengths that challenge previous assumptions.
“It is often assumed that the gravitational wave background will be uniformly distributed across the sky,” said Rowina Nathan, an astronomer at OzGrav and Monash University.
“The galactic-sized telescope formed by the MeerKAT pulsar timing array has allowed us to map the structure of this signal with unprecedented precision, which may reveal insights about its source.”
The astronomers uncovered further evidence of gravitational wave signals originating from merging supermassive black holes, capturing a signal stronger than similar global experiments, and in just one-third of the time.
“What we’re seeing hints at a much more dynamic and active universe than we anticipated,” Dr. Miles said.
“We know supermassive black holes are out there merging, but now we’re starting to ask: where are they, and how many are out there?”
Using the pulsar timing array, the researchers constructed a highly detailed gravitational wave map, improving upon existing methods.
This map revealed an intriguing anomaly — an unexpected hotspot in the signal that suggests a possible directional bias.
“The presence of a hotspot could suggest a distinct gravitational wave source, such as a pair of black holes billions of times the mass of our Sun,” Nathan said.
“Looking at the layout and patterns of gravitational waves shows us how our Universe exists today and contains signals from as far back as the Big Bang.”
“There’s more work to do to determine the significance of the hotspot we found, but this an exciting step forward for our field.”
“These findings open up exciting questions about the formation of massive black holes and the Universe’s early history.”
“Further monitoring with the MeerKAT array will refine these gravitational wave maps, potentially uncovering new cosmic phenomena.”
“The research also has broad implications, offering data that may aid international scientists in exploring the origins and evolution of supermassive black holes, the formation of galaxy structures, and even hints of early universe events.”
The results were published in three papers in the Monthly Notices of the Royal Astronomical Society.
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Matthew Miles et al. 2024. The MeerKAT Pulsar Timing Array: The 4.5-year data release and the noise and stochastic signals of the millisecond pulsar population. MNRAS, in press; doi: 10.1093/mnras/stae2572
Matthew Miles et al. 2024. The MeerKAT Pulsar Timing Array: The first search for gravitational waves with the MeerKAT radio telescope. MNRAS, in press; doi: 10.1093/mnras/stae2571
Kathrin Grunthal et al. 2024. The MeerKAT Pulsar Timing Array: Maps of the gravitational-wave sky with the 4.5 year data release. MNRAS, in press; doi: 10.1093/mnras/stae2573
