Scientists could detect the largest known black hole merger to date, a massive collision from two massive space-time ruptures swirling with each other – and hold evidence for the most elusive type of black hole in the universe.
The merger that took place outside our Milky Way galaxy produced about 225 times more black holes than the sun.
This was almost twice the previous record holder, producing the final black hole with a solar mass of about 142. The new collision was discovered by the Ligo-Virgo-Kagra (LVK) Collaboration. This is a group of four detectors that identify cataclysmic universe events from gravitational waves that ripple over awakening. Gravitational waves are ripples in space-time fabrics, first predicted to be present by Albert Einstein, confirmed by Rigo in 2015. Due to their groundbreaking discoveries, physicists involved in the research won the Nobel Prize in 2017.
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However, what is most interesting to scientists is the mass of two black holes. It is about 100 times and 140 times the sun. As with previous detections, black holes of these sizes fall into a “mass gap” that challenges traditional wisdom about how space-time ruptures form. The researchers will be presented at the 24th International Conference on General Theory of Relativity and Gravity (GR24) and the 16th Edoardo Amaldi Conference held in Glasgow, Scotland from July 14th to 18th.
“We expect that when a star dies, most black holes will form. If the star is huge enough, it will collapse into a black hole,” Mark Hannham, a professor of physics at Cardiff University in Wales and a member of the LVK collaboration, told Live Science. “But for truly huge stars, our theory is that the collapse is unstable and most masses are blown up in the supernova explosion, and no black holes are formed.”
“I don’t think black holes will form between about 60 and 130 times the mass of the sun,” he added. “In this observation, the black hole appears to be within its mass range.”
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Black holes are born from the collapse of giant stars and grow by purring gas, dust, stars and other black holes. Currently, known black holes fall into two categories. A black hole with a star mass range of several times to tens of times the mass of the sun. And ultra-high Massive black holes, like the Sun, which can range from about 100,000 to 50 billion times.
However, those that fall into the gap between these two mass ranges known as intermediate mass black holes remain extremely rare as they cannot physically form from direct star collapse. Nevertheless, hints of their existence have been discovered, leading astrophysicists to assume that these black holes grow from merging with others of similar size.
Evidence of this merger arrived on November 23, 2023, when two minimal distortions in space-time passed through the Gravitational Wave Observatory (LIGO) detectors of laser interferometers in Louisiana and Washington. Two detectors with two L-shaped 2.5 miles (4 km) arms, including two identical laser beams of two L-shaped 2.5 miles (4 km) are designed so that when gravitational waves pass through Earth, the laser light from one arm of the detector is compressed, and the other arm expands, leading to small changes in the length of the relative path of the beam.
The signal that reached the detector was born from two complex, rapidly rotating high-mass black holes. Astronomers usually analyze the mergers of black holes by modeling signals from different types of black hole binary systems and match them with new signals.
However, for this technique to work, the model must be accurate. Also, Einstein’s equations are difficult to solve (and therefore have low accuracy) when the black hole is rotating quickly.
“The black hole in GW231123 appears to be very rotating, and our different models have different results,” Hannam said. “So I’m sure black holes are very large, but they don’t measure masses particularly accurately. For example, the potential mass of a small black hole is spreading across the mass gap.”
These models need to be refined for scientists to get better calculations of these masses.
Such detection is possible. Gravitational wave detectors from Ligo, Virgo and Kagra have discovered 300 mergers since the start of their first run in 2015, with 200 found in their fourth run. However, according to facility director David Reitze, Ligo, funded by the National Science Foundation, is facing Trump administration’s budget cuts that could close one detector, making current detection “nearly impossible.”
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