Comments on: Blaming Black Holes for Gamma Ray Bursts

By: IVAN3MAN

IVAN3MAN — Tue, 22 Sep 2009 01:23:31 +0000

By: Nereid

Nereid — Sat, 19 Sep 2009 18:42:06 +0000

Oops, posted too soon …

"observational evidence to support them" (black holes): there's no shortage of observational evidence to support black holes, is there? (If you don't know of the enormous amount of such evidence, I'd be happy to give you references to hundreds of papers reporting just that).

"if this theory has solid ground": it's not clear whether you are referring to the BH-GRB link in this UT story, or black holes in general. If the latter, then the theory is about as extensively tested of any in contemporary physics (you do know, don't you, that General Relativity is the underlying theory?)

By: Nereid

Nereid — Sat, 19 Sep 2009 18:38:18 +0000

@Spoodle58: I'm not sure what you mean by "black holes are all theory anyway", would you please elaborate?

I mean, depending on what you think "theory" is, almost everything in physics is "all theory"! For example, quarks, the metastable states of doubly ionised oxygen that give rise to the intense 500.7 nm emission lines of so many nebulae, cosmic rays with energies of 10^20 eV, …

By: Spoodle58

Spoodle58 — Sat, 19 Sep 2009 15:44:31 +0000

Well as black holes are all theory anyway, this would be interesting observational evidence to support them, if this theory has solid ground of course.

By: Nereid

Nereid — Sat, 19 Sep 2009 14:54:35 +0000

@IVAN3MAN, Torbjorn Larsson OM: let's not make assumptions!

Why not let davesmith_au explain what he means? Perhaps he has mis-understood at least some of the relevant physics and/or astrophysics?

If he's interested in getting a deeper appreciation for the enormous amount of scientific work that's been done on black holes, we shouldn't decline to help him, should we?

By: Torbjorn Larsson OM

Torbjorn Larsson OM — Sat, 19 Sep 2009 13:50:27 +0000

So maybe some GRB's aren't deathscreams of suicidal stars, but of cosmic murder. Cool, sort of.

So for a BH to eat up another star the orbits of the two original stars must have been wildly eccentric.

Picky eaters, huh? I haven't looked at the paper (thanks anyway, IVAN3MAN!), but wouldn't chances be the orbits become wildly eccentric if they start to encounter each other?

@ Nereid, IVAN3MAN:

It looks more like a swollen bladder to me.

But trolls will be trolls. All you can do is pat them on their head and ask them to play outside.

By: IVAN3MAN

IVAN3MAN — Sat, 19 Sep 2009 12:57:47 +0000

@ Nereid,

In davesmith_au's case, it's not beef, it's kangaroo meat!

By: Nereid

Nereid — Sat, 19 Sep 2009 12:46:34 +0000

@davesmith_au: what's your beef with black holes?

By: davesmith_au

davesmith_au — Sat, 19 Sep 2009 12:41:31 +0000

IVAN3MAN wrote:
The black hole acts like a parasite, diving into the normal star, spinning it with gravitational forces on its way to the star's centre, and finally eating it from the inside.

A good title for an astronomy book: Death From Within!

More like a Science Fiction book, IMO.

By: Lawrence B. Crowell

Lawrence B. Crowell — Sat, 19 Sep 2009 12:05:21 +0000

A BH formed by stellar collapse ~ 5-10 km in radius while the star it devours would be ~10^6km in radius. So for a particularly violent "tango" between the BH and the other star maybe the BH can enter its interior, maybe passing through a number of time before eventually collapsing it.

From a dynamics perspective of particles in gravity fields it is hard to get the particle to enter the black hole. The angular momentum of the orbit must be nearly zero, or in other words the particle aimed pretty dead on to get it through the horizon. So for a BH to eat up another star the orbits of the two original stars must have been wildly eccentric.

By: DrFlimmer

DrFlimmer — Sat, 19 Sep 2009 11:56:27 +0000

@ William 928

Actually, nobody really knows what a GRB is. There are some very good ideas that seem plausible, but research is going on.

By: Surak

Surak — Sat, 19 Sep 2009 04:02:39 +0000

Willaim928, please read the article again.

Some GRB's are caused by supernovae. A black hole may be able to generate a GRB through the interaction of it's magnetic field, it's angular momentum, and a big injection of matter (much of the matter is ejected in a focused beam by the magnetic field). The black hole was created by the death of another star.

By: William928

William928 — Sat, 19 Sep 2009 02:26:58 +0000

I'm a bit confused by this article. Don't GRB's result from a star going supernova? How can a black hole generate its own GRB? Wasn't the black hole created by the death of the star?

By: Lawrence B. Crowell

Lawrence B. Crowell — Sat, 19 Sep 2009 01:45:29 +0000

I have a number of problems with this model. While black hole have enormous gravity field up close it is actually rather hard to get something into them. The star which is eaten up is not likely to do this with a direct head on collision. It would likely be the that the black hole and star are in some sort of co-orbit that decays and the star is tidally distorted with an accretion disk and eventually the black hole enters it. I should think there would be lots of energetics leading up to the burst.

By: IVAN3MAN

IVAN3MAN — Fri, 18 Sep 2009 22:53:51 +0000

The black hole acts like a parasite, diving into the normal star, spinning it with gravitational forces on its way to the star's centre, and finally eating it from the inside.

A good title for an astronomy book: Death From Within!

By: IVAN3MAN

IVAN3MAN — Fri, 18 Sep 2009 22:38:45 +0000

The relevent paper is available here:
Close Binary Progenitors of Long Gamma Ray Bursts [PDF].

By: Sili

Sili — Fri, 18 Sep 2009 21:57:32 +0000

Don't cry, black holes. I love you.

I need to read up on GRBs, I guess. The idea of stuff being so dense that it can be heated by neutrinos is awesome.

By: DrFlimmer

DrFlimmer — Fri, 18 Sep 2009 20:52:15 +0000

Interesting article, indeed! And btw a very intersting field of research, just like everything that has to do with black holes. I can spot lots of work at the (event) horizon……