Biggest black hole merger yet detected by gravitational waves


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The uncertainty of science: In May 2020 scientists using the LIGO and VIGO gravitational waves telescopes detected evidence of a merger from two giant black holes, one of which was of a size that according to all theories had been considered “impossible.”

The short gravitational wave signal, GW190521, captured by the LIGO and Virgo gravitational wave observatories in the United States and Europe on 21 May last year, came from two highly spinning, mammoth black holes weighing in at a massive 85 times and 66 times the mass of the Sun, respectively.

But that is not the only reason this system is very special. The larger of the two black holes is considered `impossible’. Astronomers predict that stars between 65 – 130 times the mass of the Sun undergo a process called pair instability, resulting in the star being blown apart, leaving nothing behind.

With a mass of 85 solar masses, the larger black hole falls squarely in that forbidden range, referred to as the upper black hole mass gap, and should be `impossible’.

The explanation the scientists propose is that this black hole initially formed with a mass smaller than 65 solar masses, and then sucked in matter, including a possible additional black hole merger, that raised its weight to 85 solar masses.

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3 comments

  • Max

    The uncertainty of science:

    “The signal, resembling about four short wiggles, is extremely brief in duration, lasting less than one-tenth of a second. From what the researchers can tell, GW190521 was generated by a source that is roughly 5 gigaparsecs away, when the universe was about half its age, making it one of the most distant gravitational-wave sources detected so far.”

    “This doesn’t look much like a chirp, which is what we typically detect,” says Virgo member Nelson Christensen, a researcher at the French National Centre for Scientific Research (CNRS), comparing the signal to LIGO’s first detection of gravitational waves in 2015. “This is more like something that goes ‘bang,’ and it’s the most massive signal LIGO and Virgo have seen.”

    “But what if something entirely new produced these gravitational waves? It’s a tantalizing prospect, and in their paper the scientists briefly consider other sources in the universe that might have produced the signal they detected. For instance, perhaps the gravitational waves were emitted by a collapsing star in our galaxy. The signal could also be from a cosmic string produced just after the universe inflated in its earliest moments — although neither of these exotic possibilities matches the data as well as a binary merger.”
    https://www.ligo.org/detections/GW190521/files/pr-english.pdf

  • wayne

    “Pair Instability Supernova”
    Anton Petrov ->August 2019
    https://youtu.be/WqDI4ojw-94
    11:08

  • wayne

    This is very informative, although way too short->

    Stan Woosley:
    “Pair-Instability Supernovae”
    Sackler Conference 2016
    https://youtu.be/0seHmcpg3gY
    34:01

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