Sometimes nature is unlocked when we explore the way we look at it.
Black holes remain a focal point for cosmic mysteries, one of which begs the question: why do black holes often have more mass than originally intended? A team of astronomers has now proposed a new model to address this difficulty, suggesting that black hole growth may be “cosmologically linked” to the expansion of the entire universe, according to a recent study. published in the journal Astrophysical Journal Letters.
And that could make gravitational wave observatories more sensitive, including the future ones that will be launched into space.
The black holes and the mystery of the excess mass
As early as 2015, the LIGO facility detected gravitational waves for the first time. Gravitational waves are literal waves that pass through the main fabric of space-time and are generated by unconsciously violent events in the universe, such as the merging of two black holes into a larger one. Astronomers know how to reverse the flow of data from these waves to trace their way back in time and calculate the masses of the two cosmic monsters merging. And when they did, something strange happened. The most common type of black holes in the universe that the team expected to find are responsible for most of the mergers, those with masses comparable to the mass of the sun, called stellar black holes. They are approximately 30 times the mass of our host star, but the LIGO team has identified many black holes with masses that far exceed that. The most massive collision ever occurred occurred between two black holes with masses between 65 and 85 suns.
This is more than twice to almost three times the mass of the sun, much higher than expected. But how did it happen? The conventional explanation suggests that they became large by swallowing unimaginable volumes of matter, such as gas, dust, whole stars, or even other black holes. But a new study by researchers has come up with another, wilder explanation: black hole masses can grow, like the universe, into a phenomenon the research team calls cosmological connectivity. This is not something they just came up with, and the researchers in the new study are not the first to consider the idea. Einstein’s theory of relativity suggests this possibility, and the fact is that light is already cosmologically connected in some way.
Cosmological connectivity may increase the sensitivity of future gravitational wave observatories
Namely, light loses energy with the growth of the universe, which reinforces this expansion as feedback. “We were thinking of looking at the opposite effect,” said Duncan Farah, co-author of the study, in a New atlas report. “What would LIGO-Virgo observe if black holes were cosmologically connected and accumulated energy without the need to consume other stars or gas?” The research team noted that the normal way to model black holes is within simulated universes that do not take into account cosmic expansion. This was a convention to simplify math, but researchers suspected it could hide the effects of cosmological connectivity. This inspired them to launch simulations involving the expansion of the universe.
Researchers have simulated millions of binary star systems throughout their lives, from birth to death and transformation into black holes. And because these black holes were connected to the growth inherent in cosmological expansion, they became even more massive as the eons passed, stopping inward as the couple merged into a catastrophic collision. This finding may help test procedures for gravitational wave observatories to be more sensitive to future events and to do the same for new gravitational observatories such as LISA (which may have a better shot in space) is yet to join the hunt for these giant cosmic waves. This is an exciting time to look at the universe.