Any Theoretical Physicists here?

[Mike03]

I'm really curious about these stories about the ultra high energy cosmic rays being emitted by black holes (according to the BBC).

Wouldn't this be rather unexpected, even if you take into account Hawking Radiation? Or are these rays Hawking Radiation?

Or is it misleading for the articles to state that the rays are "emitted" by black holes? I can imagine rays being sped up by black holes as they circumnavigate the event horizon, but if they are truly coming out of black holes, wouldn't that violate some central beliefs about black holes?

Is this as important a story as it sounds?

Comments would be appreciated.

[HiFructosePronSyrup]

1. I think you're misinterpreting the use of the word "emitted."

They're not talking about hawking radiation.

Just Ohmygod particles coming from black holes.

Presumably regular particles that are accelerated by the "gravity slingshot." They never cross the event horizon.

I don't know why you'd think it important.

[Mike03]

2. I meant it would be important if they were coming

from within a black hole, since most people are taught that nothing can come out of a black hole.

[Mike03]

3. But thanks for the clarification NT

[Lionel Mandrake]

4. You are partially correct.

Certainly the cosmic rays in question do not cross the event horizon. Nor are they Hawking radiation.

But the mechanism of acceleration could not possibly be a "gravity slingshot". The gravity from a supermassive black hole at the center of a galaxy would not accelerate a cosmic ray. The acceleration mechanism must involve matter that is orbiting the black hole.

[HiFructosePronSyrup]

6. Cosmic rays are matter.

Usually protons.

It's stuff that comes from the jets, presumably. Matter falls towards the black hole, forms an accretion disk, goes faster and faster, heats up, gets faster and faster, then gets spat out in jets. The exact mechanism of how jets work is unknown, but slingshoting is something lay persons understand, sort of.

That said, this article doesn't say any of this. They simple correlate ohmygod particles with specific points in the sky instead of broad distribution, those points correlate with the distribution of AGNs.

[Lionel Mandrake]

13. Indeed they are.

But my point was that the cosmic rays (which are atomic nuclei) must be interacting with other matter in the vicinity of the black hole. More specifically, the interaction must be with electromagnetic fields generated by the other matter.

What is observed on the ground is a shower of secondary particles resulting from the impact of the primary cosmic ray on the upper atmosphere. The geometry of the measurements indicates the approximate direction of the primary cosmic ray. The correlation of these directions with known active galactic nuclei is evidence that supermassive black holes are involved.

As you said, the exact mechanism of acceleration is unknown.

[GreenPartyVoter]

5. Do you mean gamma ray bursts or something else?

[HiFructosePronSyrup]

7. Something else.

High energy cosmic rays, dubbed "ohmygod" particles. Protons travelling so fast they carry the kinetic energy of a Nolan Ryan fastball.

A recent Science paper correlated them with supermassive blackholes.

[redqueen]

8. Why that name?

Weird.

[GreenPartyVoter]

9. Cool. I am looking them up on wikipedia even now.

[Mike03]

10. No wonder non-scientists are so afraid of physicists NT

[rug]

11. I see Lounge standards are slipping.

[Fredda Weinberg]

12. The way I was taught ... it's quantum mechanics writ large

The only time the micro and macro scale resemble each other is at an event horizon. So, while no matter can leave the gravity well of the central mass ... the probability is not 0 and the resulting radiation is predictable. Miniscule in comparison to the energy consumed - and the part that should twist your noodle is where all that energy goes, but I have my own equations - the escaping particles have enough energy to radiate this far, however long it takes.

Particles ... again, you gotta take the macro scale. Black holes eat planets, even suns around 'em and something spills, so to speak.

The rest is math.