By harnessing the extraordinary capabilities of South Africa's world-renowned MeerKAT radio telescope, scientists at the University of Cape Town (UCT) in partnership with the South African Radio Astronomy Observatory (SARAO) and several leading global institutions have made new, innovative strides in unveiling mysteries of the universe.
Thanks to this partnership, compelling evidence for a low-frequency gravitational wave background - cosmic ripples in spacetime that stretch and squeeze the fabric of the universe - has emerged. The findings stem from MeerKAT Pulsar Timing Array Project, a five-year initiative that kicked-off in 2019, using the precision of pulsars as natural cosmic clocks. These celestial bodies are located thousands of light years away, act as the largest galactic gravitational wave detector of its kind and produces the most detailed gravitational wave maps ever created. MeerKAT's state-of-the-art design, developed by SARAO and operated as a National Research Foundation (NRF) facility, continues to push the boundaries of astronomical research.
"To find evidence for a gravitational wave background, we first need to model the timing behaviour of each of the pulsars in our network very precisely. Once we know the individual pulsars well, we can start analysing the combined behaviour of the group of pulsars. If we see pulsars in the same direction in the sky lose time in a connected way, we start suspecting that it is not the pulsars that are acting funny, but rather a gravitational wave background that has interfered," said Dr Marisa Geyer, co-author and lecturer at UCT and former commissioning scientist of MeerKAT.
Ground-breaking findings
In just one-third of the time when compared to other global experiments, the MeerKAT team is seeing signs of a gravitational wave background. The background, likely from merging supermassive black holes, is also a stronger signal than other published results. These and other findings, which offer unprecedented insights into the likely sources of these spacetime ripples - primarily the colossal merges of supermassive black holes - were published in the Monthly Notice of the Royal Astronomical Society, a peer-reviewed scientific journal, which showcases the power of collaboration between international partners from South Africa, Australia, Europe and SARAO.
"It is amazing to see that with MeerKAT evidence for [a] signal is possible, even in a data-span of just 4.5 years."
"Pulsar timing array experiments are long-term in nature, and searching for a gravitational wave background is a slow process. From past experience, we know that this may need 15 years of data. It is amazing to see that with MeerKAT evidence for [a] signal is possible, even in a data-span of just 4.5 years," said Dr Jaikhomba Singha, a postdoctoral research fellow in UCT's Faculty of Science.
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This research project sets a firm foundation to further explore the evolution of galaxies and the formation of supermassive black holes. And the upcoming SKA-Mid telescope, which is currently under construction in the Karoo and incorporates MeerKAT, promises to expand these discoveries even further and position South Africa as a leader at the forefront of the next generation of cosmic exploration.
