Boffins on alert: Brace yourselves for huge gravitational wave coming within a decade

When supermassive black holes collide, we'll feel it

The most violent gravitational waves in the universe from supermassive black hole prangs will be detected to within ten years, according to research published on Monday.

Gravitational waves were predicted by Albert Einstein and finally discovered in 2015, a century after his theory of general relativity was formalized. Ripples through spacetime are generated when black holes collide. As they combine, a proportion of their mass is converted to energy and radiates away as a gravitational wave.

So far, the waves detected by the Laser Interferometer Gravitational Observatory (LIGO) and Virgo have been from the mergers of black holes less than a hundred solar masses. That’s tiny compared to the gargantuan monsters lurking in the center of galaxies that can be millions or even billions of solar masses.

The gravitational waves between these colliding supermassive black holes will be observable within a decade, according to a paper published in Nature today.

black hole

Gravitational waves permanently change spacetime, say astroboffins


Chiara Mingarelli, lead author of the study and a research fellow at the Center for Computational Astrophysics at the Flatiron Institute in New York City, said the signals “from these supermassive black hole binary mergers are the most powerful in the universe. They absolutely dwarf the black hole mergers detected by LIGO."

Although they are the most powerful source of gravitational waves, current observatories will never be able to sniff them out because they are not sensitive to the same wavelengths of the wave.

To hunt for these large ripples, astronomers will have to focus their attention to pulsar stars instead. These objects are fast spinning neutron stars that flash beams of radio waves, leftover material from dead stars.

If a gravitational wave emitted from a supermassive black hole merger event passed by a pulsar, the rhythm of its flickering light will be affected. The space between Earth and the pulsar will be stretched and compressed as the wave passes through, allowing scientists monitoring the pulsar signals to detect the signals.

There are already three projects currently measuring the time of the radio waves from pulsars: the Parkes Pulsar Timing Array in Australia, North American Nanohertz Observatory for Gravitational Waves and the European Pulsar Timing Array. Together, the trio forms the International Pulsar Timing Array.

The researchers gathered data to count the number of nearby galaxies that may host pairs of supermassive black holes, and combined it with a map of nearby pulsars to calculate the probability that a powerful gravitational wave signal would be detected.

"If you take into account the positions of the pulsars in the sky, you basically have a 100 percent chance of detecting something in 10 years," Mingarelli said. "The bottom line is that you're guaranteed to select at least one local supermassive black hole binary."

Not so fast, what about the final parsec problem?

A surprising result was that the most energetic gravitational waves could be the most difficult to detect.

Despite larger galaxies housing bigger supermassive black holes, the large masses mean that the collisions are faster and more violent. It reduces the window of time that the gravitational waves can be detected. A merger event in a giant galaxy like M87, for example, would emit detectable signals for about four million years. But a smaller galaxy like the Sombrero Galaxy has a longer window of 160 million years.

Sombrero galaxy

The Sombrero galaxy measuring about 15 kiloparsecs or about 50,000 light years across. Image credit: NASA/Hubble Heritage Team

Detecting these impacts will give researchers a way to study how massive galaxies merge, an important step to understanding how the universe evolves over time. If the scientists fail to find such an event, it could be because colliding supermassive black holes slow down when they are separated by three light years or one parsec.

The ‘Final Parsec Problem’ describes a situation where the supermassive black holes spiralling into one another have to lose energy to its surroundings in order to smash into one another. But as they get so close to one another, nearby stars and gas have been booted away that there is now less material to transfer energy to and so they fall into each other more slowly.

That process could take longer than the current age of the universe, so “it’ll be interesting either way,” Mingarelli said. ®

Other stories you might like

  • Experts: AI should be recognized as inventors in patent law
    Plus: Police release deepfake of murdered teen in cold case, and more

    In-brief Governments around the world should pass intellectual property laws that grant rights to AI systems, two academics at the University of New South Wales in Australia argued.

    Alexandra George, and Toby Walsh, professors of law and AI, respectively, believe failing to recognize machines as inventors could have long-lasting impacts on economies and societies. 

    "If courts and governments decide that AI-made inventions cannot be patented, the implications could be huge," they wrote in a comment article published in Nature. "Funders and businesses would be less incentivized to pursue useful research using AI inventors when a return on their investment could be limited. Society could miss out on the development of worthwhile and life-saving inventions."

    Continue reading
  • Declassified and released: More secret files on US govt's emergency doomsday powers
    Nuke incoming? Quick break out the plans for rationing, censorship, property seizures, and more

    More papers describing the orders and messages the US President can issue in the event of apocalyptic crises, such as a devastating nuclear attack, have been declassified and released for all to see.

    These government files are part of a larger collection of records that discuss the nature, reach, and use of secret Presidential Emergency Action Documents: these are executive orders, announcements, and statements to Congress that are all ready to sign and send out as soon as a doomsday scenario occurs. PEADs are supposed to give America's commander-in-chief immediate extraordinary powers to overcome extraordinary events.

    PEADs have never been declassified or revealed before. They remain hush-hush, and their exact details are not publicly known.

    Continue reading
  • Stolen university credentials up for sale by Russian crooks, FBI warns
    Forget dark-web souks, thousands of these are already being traded on public bazaars

    Russian crooks are selling network credentials and virtual private network access for a "multitude" of US universities and colleges on criminal marketplaces, according to the FBI.

    According to a warning issued on Thursday, these stolen credentials sell for thousands of dollars on both dark web and public internet forums, and could lead to subsequent cyberattacks against individual employees or the schools themselves.

    "The exposure of usernames and passwords can lead to brute force credential stuffing computer network attacks, whereby attackers attempt logins across various internet sites or exploit them for subsequent cyber attacks as criminal actors take advantage of users recycling the same credentials across multiple accounts, internet sites, and services," the Feds' alert [PDF] said.

    Continue reading

Biting the hand that feeds IT © 1998–2022