Can Colliding Black Holes Solve the Mystery of Short-Duration Gamma-Ray Bursts?

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Discussion Overview

The discussion centers on the relationship between colliding black holes and short-duration gamma-ray bursts (SGRBs). Participants explore theoretical models, implications of general relativity (GR), and the observational characteristics of SGRBs in relation to black hole mergers.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant proposes that if two equal mass black holes collide at their respective Schwarzschild radii, it might allow matter/energy to escape along a neutral plane, questioning the effects of rotation and angles of approach.
  • Another participant emphasizes the importance of understanding GR in the context of black hole mergers, suggesting that such events would primarily result in gravitational radiation without matter escaping.
  • A participant mentions that some short gamma-ray bursts may be linked to merging black holes, but this connection is questioned.
  • Concerns are raised regarding the distance distribution of SGRBs and why their numbers would not increase as the universe becomes less ancient, suggesting a potential inconsistency in the merging black hole hypothesis.
  • Further clarification is sought on how an older universe could have more black holes, with a participant arguing that stellar mass black holes should become more numerous as the universe ages.
  • One participant acknowledges a misunderstanding regarding the age of the universe and its implications for black hole numbers, seeking further arguments against the merging black hole interpretation of SGRBs.
  • A link to a study on the demographics of galaxies hosting SGRBs is shared, noting the limited data available and the ongoing mystery surrounding SGRBs compared to long-duration gamma-ray bursts (LGRBs).

Areas of Agreement / Disagreement

Participants express differing views on the relationship between black hole mergers and SGRBs, with some supporting the connection while others raise significant questions and challenges to this hypothesis. The discussion remains unresolved regarding the implications of black hole population dynamics and their relation to gamma-ray bursts.

Contextual Notes

Participants highlight limitations in current understanding, including the dependence on observational data and the complexities of modeling black hole mergers within the framework of GR.

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If two black holes with equal mass were to collide when they reach the point where their respective centers are at the schwarzchild radius of the other black hole could the spacetime distortions caused by their masses cancel out in such a way that matter/energy could escape along the plane of neutrality between their centers? Could there be other solutions if they are rotating or approaching one another at odd angles or tangentially to their surfaces?
 
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This sort of thing has been modeled in ever more detail using numerical relativity. It is important to understand what GR says about this process as well as possible because it would be an intense source of gravitational radiation. Detecting the predicted character of such an event would be a stringent test of GR in a new domain.

What is expected per GR is simply a merger, with 'ring down' of the event horizons with release of characteristic, intense gravitational radiation. There is no indication of any possibility for matter to escape.

A good place to browse for the latest on this is: http://www.black-holes.org, for example: http://www.black-holes.org/explore2.html
 
Something related you might would want to check out are "short gamma-ray bursts".
Some of them are considered to be merging black holes.
Hope that helps.
 
The problem with the short gamma ray burst explanation as merging black holes is it fails to account for their distance. Why wouldn't their numbers tend to increase as cosmological distance decreases, where the universe is more ancient and black holes are consequently more numerous?
 
Chronos said:
The problem with the short gamma ray burst explanation as merging black holes is it fails to account for their distance. Why wouldn't their numbers tend to increase as cosmological distance decreases, where the universe is more ancient and black holes are consequently more numerous?

The bolded part doesn't make sense to me. As cosmological distances decrease, we are seeing a LESS ancient universe, are we not?

In any case, why would an older universe have more black holes? That implies that the universe has been losing black holes over time, whereas I thought it had been gaining black holes over time.
 
I think you misunderstood me, Phinds, stellar mass black holes should become increasingly numerous as the universe [and stars within it] ages. The nearby universe is more ancient than more remote [high redshift] regions. In fact, we reside in the most ancient region in the known universe. The light we receive from the moon is 1/4 second younger than us, the sun several minutes, alpha centauri about 4 years, etc.
 
Chronos said:
I think you misunderstood me, Phinds, stellar mass black holes should become increasingly numerous as the universe [and stars within it] ages. The nearby universe is more ancient than more remote [high redshift] regions. In fact, we reside in the most ancient region in the known universe. The light we receive from the moon is 1/4 second younger than us, the sun several minutes, alpha centauri about 4 years, etc.

But then I don't understand how this conflicts with the interpretation of SGRBs being binary black hole mergers. Could you give your arguments for this suggestion?
 
Chronos said:
I think you misunderstood me, Phinds, stellar mass black holes should become increasingly numerous as the universe [and stars within it] ages. The nearby universe is more ancient than more remote [high redshift] regions. In fact, we reside in the most ancient region in the known universe. The light we receive from the moon is 1/4 second younger than us, the sun several minutes, alpha centauri about 4 years, etc.

You are right ... don't know how I confused myself on this one, but I clearly did. Thanks.
 
Here is a link that may be interesting: Demographics of the Galaxies Hosting Short-duration Gamma-Ray Bursts; http://arxiv.org/abs/1302.3221. Obviously, we have limited data about galaxies where SGRB's occur [they are, after all, of short duration by definition]. The consensus is they tend to be more nearby than LGRB's, but, that species is also much brighter, hence, visible at greater distances. It is suspected that LGRB's originate from ginormous stars in young galaxies - which makes sense. SGRB's are still pretty much a mystery.
 

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