5 ms·

260hz is not unreasonable, black hole mergers are unimaginably violent. https://youtu.be/9IdVyArDlZ4 https://youtu.be/9IdVyArDlZ4

clort 6y ago
yes but I'm imagining that when the orbital frequency gets to that kind of level, the end would be extremely imminent? (for the remote observer anyway haha)
- maxnoe 6y ago
  Yes, LIGO observes the actual merger. They report two initial masses, the final mass of the merged black hole and what as a result was radiated in energy.
- Jabbles 6y ago
  Yes, but it's only when the black holes get extremely close that they produce gravitational waves powerful enough for us to detect. You're correct that for many years (millenia?) the black holes have been orbiting each other much more slowly. We can't detect that though.
  - foota 6y ago
    I wonder what the right time scale is here. My gut reaction is million of years?
    - enkid 6y ago
      I believe it depends on the specifics of the merger, but my understanding is the reason black holes that orbit each other merge at all is because they bleed energy to gravitational waves. While they are at a reasonable distance, that's a very small amount of energy. I think some of these systems would be stable for billions of years.
      - foota 6y ago
        Billions seemed too long to me, at that point you're talking about tenths of the lifetime of the universe!
        enkid 6y ago
        That's the timescale the solar system is stable on.
        foota 6y ago
        Aw, sorry. I think I mis-interpreted your comment. I was thinking more of how long the system has been falling apart for. It didn't make sense to me that that could have been for billions of years, since the movement involved would be so slow?
jcims 6y ago
Just for folks that aren't familiar pulsars are spinning stars that can hold themselves together up to at least ~1khz. Here's what the signal sounds like coming from a few different ones (incl. 600hz range) https://www.youtube.com/watch?v=gb0P6x_xDEU https://www.youtube.com/watch?v=gb0P6x_xDEU

clort 6y ago

yes but I'm imagining that when the orbital frequency gets to that kind of level, the end would be extremely imminent? (for the remote observer anyway haha)

maxnoe 6y ago
Yes, LIGO observes the actual merger. They report two initial masses, the final mass of the merged black hole and what as a result was radiated in energy.
Jabbles 6y ago
Yes, but it's only when the black holes get extremely close that they produce gravitational waves powerful enough for us to detect. You're correct that for many years (millenia?) the black holes have been orbiting each other much more slowly. We can't detect that though.
- foota 6y ago
  I wonder what the right time scale is here. My gut reaction is million of years?
  - enkid 6y ago
    I believe it depends on the specifics of the merger, but my understanding is the reason black holes that orbit each other merge at all is because they bleed energy to gravitational waves. While they are at a reasonable distance, that's a very small amount of energy. I think some of these systems would be stable for billions of years.
    - foota 6y ago
      Billions seemed too long to me, at that point you're talking about tenths of the lifetime of the universe!
      - enkid 6y ago
        That's the timescale the solar system is stable on.
        foota 6y ago
        Aw, sorry. I think I mis-interpreted your comment. I was thinking more of how long the system has been falling apart for. It didn't make sense to me that that could have been for billions of years, since the movement involved would be so slow?

jcims 6y ago

Just for folks that aren't familiar pulsars are spinning stars that can hold themselves together up to at least ~1khz. Here's what the signal sounds like coming from a few different ones (incl. 600hz range) https://www.youtube.com/watch?v=gb0P6x_xDEU https://www.youtube.com/watch?v=gb0P6x_xDEU