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For a system this small and a black hole this big, the smoking gun evidence would be a time lapse showing the stars orbiting a point with “nothing” there. The

For a system this small and a black hole this big, the smoking gun evidence would be a time lapse showing the stars orbiting a point with “nothing” there. The evidence they presented in the paper is mostly circumstantial — essentially a statistical analysis. We have this video for Sagittarius A* : https://www.eso.org/public/videos/eso1825e/ https://www.eso.org/public/videos/eso1825e/ I’m guessing that in a few years we’ll have a similar video of this area too.

dylan604 2y ago
That's the issue with timelapse of this scale. It takes many years to get a good look at it. Even in the video you linked took 20 years.
pfdietz 2y ago
The closest approaching star found so far is estimated to be traveling at 8% of the speed of light at closest approach.
- nick7376182 2y ago
  Which is enough to cause severe relativistic precession of the orbital major/minor axes! (Schwarzschild precession)
andrewflnr 2y ago
> the researchers were able to observe characteristic X-rays and ionized gas rotating at a speed of several 100 km/s in a ring around the suspected location of the intermediate-mass black hole. That's a little better than circumstantial.
- jiggawatts 2y ago
  Does that confirm the size of the black hole, or is it just a "strong hint"?
  - andrewflnr 2y ago
    Fair, I have no idea if it confirms the size, though maybe the specific speed of the gas helps with that. Mostly it's evidence that there is a black hole, but it's not supermassive, and a stellar-mass one probably wouldn't have enough effect to be noticed.
    - saagarjha 2y ago
      You can determine the mass of something by measuring the time it takes for an orbit around it, yes.
      - andrewflnr 2y ago
        You need the orbital radius, too.
        saagarjha 2y ago
        Yep. You can get both from observations of the orbiting object.
phkahler 2y ago
Is that gravitational lensing happening at the start of the video? Upper left, flickering rings but they seem to be around a star.
- itishappy 2y ago
  Looks like a diffraction pattern to me. The way it flickers makes me think they're running some corrective algorithm that's struggling with some of the stars. (See the bottom left as well, they both appear to be bright sources and also on the edge of the field.) Also interesting to note how it seems to show up more when the image is crisper. No clue why that might be. https://en.wikipedia.org/wiki/Airy_disk https://en.wikipedia.org/wiki/Airy_disk

dylan604 2y ago

That's the issue with timelapse of this scale. It takes many years to get a good look at it. Even in the video you linked took 20 years.

pfdietz 2y ago

The closest approaching star found so far is estimated to be traveling at 8% of the speed of light at closest approach.

nick7376182 2y ago
Which is enough to cause severe relativistic precession of the orbital major/minor axes! (Schwarzschild precession)

andrewflnr 2y ago

> the researchers were able to observe characteristic X-rays and ionized gas rotating at a speed of several 100 km/s in a ring around the suspected location of the intermediate-mass black hole. That's a little better than circumstantial.

jiggawatts 2y ago
Does that confirm the size of the black hole, or is it just a "strong hint"?
- andrewflnr 2y ago
  Fair, I have no idea if it confirms the size, though maybe the specific speed of the gas helps with that. Mostly it's evidence that there is a black hole, but it's not supermassive, and a stellar-mass one probably wouldn't have enough effect to be noticed.
  - saagarjha 2y ago
    You can determine the mass of something by measuring the time it takes for an orbit around it, yes.
    - andrewflnr 2y ago
      You need the orbital radius, too.
      - saagarjha 2y ago
        Yep. You can get both from observations of the orbiting object.

phkahler 2y ago

Is that gravitational lensing happening at the start of the video? Upper left, flickering rings but they seem to be around a star.

itishappy 2y ago
Looks like a diffraction pattern to me. The way it flickers makes me think they're running some corrective algorithm that's struggling with some of the stars. (See the bottom left as well, they both appear to be bright sources and also on the edge of the field.) Also interesting to note how it seems to show up more when the image is crisper. No clue why that might be. https://en.wikipedia.org/wiki/Airy_disk https://en.wikipedia.org/wiki/Airy_disk