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"Do supermassive black holes ever merge? | The Final Parsec Problem" by Dr. Becky [14min] (www.youtube.com)
submitted 3 years ago* (last edited 3 years ago) by to c/astronomy@mander.xyz
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Summary generated with claude.ai from the video transcription:

The 'final parsec problem' refers to the fact that the math predicts supermassive black holes at the centers of merging galaxies should stall at around 1 parsec separation and never actually merge. This contradicts observations suggesting supermassive black holes do merge over time. The problem arises because at around 1 parsec separation, the black holes have cleared out all stars/gas so can't lose more energy to get even closer. Gravitational waves only help below 0.01 pc. The upcoming LISA gravitational wave detector should detect mergers and help solve this problem - either the math is wrong and mergers happen, or mergers don't happen and the math is right.

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[–] 5 points 3 years ago (2 children)

What are the most interesting implications of they do or don't merge?

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  • [–] [S] 6 points 3 years ago

    (Not an expert.. by far, those who know more please correct me)

    From what I understand in the video... it would only be interesting if they are merging because it doesn't match with the theory, so they would need to find new processes to explain it.

    If they are not merging, then there aren't many implications really. One of the reasons why it's so difficult to tell if they are merging or not is because it doesn't make much of a difference. Two possible observations mentioned in the video are:

    • Trayectories of the jets of non-merged black holes can be different from jets of single black holes.
    • Gravitational waves with a frequency outside LIGO's range of detection.
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    • [–] 4 points 3 years ago (1 child)

    Maybe SBHs have bigger accretion areas than we think they do, and have daughter BHs orbiting them. That would allow them to fuse because the babies can get a lot closer, and interact via waves.

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  • [–] 1 point 3 years ago

    Or over millions/billions of years, gas and dust find their way in between, nudging these monsters closer together.

    Surely in the dense galactic cores there is still mass that periodically falls towards these black holes at the center - the Active Galactic Nuclei flickering faintly on a little bit - although I'm guessing the amount is not enough to currently explain this riddle.

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    • [–] 2 points 3 years ago

    Interesting, I had no idea.

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    [–] 2 points 3 years ago

    That LISA project looks super cool! What a piece of engineering that seems! Anyone aware of the difficulties they'll have getting everything aligned correctly for the lasers?!

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    [–] 1 point 3 years ago (1 child)

    I guess the Stronger Gravitation sucks the other one.

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