Short Gamma-ray Bursts Traced to Colliding Stars

Astervitude writes "Collisions of the cosmic kind could be the source of one of nature's most lethal explosions. Astronomers have traced the origin of short-duration gamma-ray bursts, or GRBs, to the merger of neutron stars or other dense bodies. Space.com has a report on the scientific detective work that led to the solution of what has been described as a 35-year-old mystery. "Our observations do not prove the coalescence model, but we surely have found a lady with a smoking gun next to a dead body," said Shri Kulkarni, one of over two dozen astronomers who discovered and investigated two short-duration bursts that took place last May and July. Unlike short-duration GRBs, long-duration GRBs are believed to be produced when extremely massive stars collapse and explode as supernovas."

Comments

Re:They explode, hence blackholes are a impossibil

[Yahweh Doesn't Exist]

>The proof offered for the existence of blackholes doesn't convince me. Just because there is a solution to the GR equations doesn't make it physically real.

people don't believe they exist just because of a GR solution.

they were predicted before GR but believed to be a mathematical trick that would need perfect conditions to form (perfectly symmetrical mass distribution). GR just changed that by removing these conditions (the generation of gravitational waves by mass distributions with a quadrupolar moment means).

anyway, you make it sound like it's just a case of GR for black holes. it's not - it's a huge amount of theory and observations that are all consistent. if you want respect then the first thing to do is acknowledge this work exists, and the second is to provide an alternative explanation that works at least as well.

Re:The summary

[Decaff]

especially the portion that said ...." In practice, over the few seconds that a gamma ray burst occurs, it releases almost the same amount of energy as the entire Universe! "

Which is, of course, nonsense. It should say 'the same amount of energy as the visible Universe'. Big (very, very big) difference!

Re:Astronomy vs Science

[Anonymous Coward]

What this implies is that astrophysics, as practiced, is no more science than, say, sociology.

You have something against sociology? It's a science too. And ALL sciences are practiced by human beings, who need to be convinced by evidence -- as they should.

Whenever current astrophysical theories are falsified by observation, a fundamental law gets tossed instead.

This, of course, is nonsense. The vast majority of new astrophysical phenomena find explanations within current physics.

y. Whenever current astrophysical theories are falsified by observation, a fundamental law gets tossed instead. Lately we have "dark matter" (6x as much of it as the visible universe), "dark energy" (18x as much!), "inflation", and distant galaxies producing hundreds of times more light than similar modern ones.

And your point is what? There is substantial evidence in favor of these theories, and all competing theories advanced so far have failed. Sometimes new physics is discovered, you know. Just because you want to stick your fingers in your ears and ignore the evidence in its favor, doesn't mean it's not there.

All are futile attempts to rescue the Big Bang from the oblivion it earns by being, finally, irreconcilable with observation. (E.g. light-element ratios; gravitational lensing measurements of galactic mass; fractal, filamentary arrangement of galactic superclusters; preferred direction of cosmic microwave background anisotropy; shall I go on?)

What the hell are you talking about? All of those observations SUPPORT Big Bang cosmology, rather than contradict it. (Except for one mistake on your part: there is no known preferred direction of the CMBR -- but even if there was, there are anisotropic Big Bang cosmologies with preferred directions.)

For all the claims of evidence for the role of neutron stars and black holes in galactic-scale events, it all amounts to negative evidence: those are the only way to concentrate enough energy when the only forces you are willing or equipped to work with are gravitation, fusion, and shock waves.

It is not negative evidence. Theories of neutron stars and black holes make specific predictions of what you will see, and those predictions are supported by observations.

Even so, multimillion-degree "hot gases" in free space and 10^14 eV cosmic rays remain beyond their capacity.

This turns out not to be the case. Ultra high energy cosmic rays, for one, are within the capacity of jets from supermassive black holes. One current goal is to localize the origin of these rays better to see whether they coincide with such sources.

The bigger mystery is not whether mechanisms exist to produce them, but why these rays are appearing to exceed the GZK cutoff, which sets an upper bound on the energy of distant cosmic rays that we can detect. (Some possibilities: the experiments are miscalibrated, which is distinctly possible since HiRES and AGASA's curves look the same except one is shifted by 20%; the cosmic rays are nearer in origin than we think; there is new physics or an unaccounted effect that allows violation of the GZK prediction. All are being investigated, and new expriments such as the Pierre Auger observatory should shed light on this question.)

Current flow in interstellar plasmas easily propagates and concentrates such energies, without reliance on untestable physical laws and ghosts. However, such work can, as a rule, only be published in Plasma Science journals not read (and perhaps not readable) by astrophysicists.

Oh, I get it, you're a plasma cosmology crank. Well, no, you're wrong: plasma physics gets published in astrophysics journals all the time. Just look at the astro-ph arXiv. However, crank physics which purports to expl

Re:A few questions about GRBs

[imsabbel]

If there were "a few per year" from our galaxy, live would have never evolved on earth... (just think about it: a few per year over the the time earth exists is about 10 billion GRBs ....

I dont know if we _EVER_ have observed a GRB in our galaxy, the detected ones are very isotropically distributed over the sky and in the _deep_ background. Most have a z>0.1 and are FAR away.

And the killing ratio for a GRB would be more like 100-250 ly. 10 ly away even a normal supernova would be an extinction event.

Just use some fermi logic:
If a GRB is the result of the collision of 2 neutron start, than they are at least twice as rare as supernovas (somewhere those NS have to come from, plus many supernovas dont leave a neutron star).
and after that, there has to be a situation when 2 are able to merge (which 99.9% only happens in close binary start, as 2 neutron start hitting each other has a laughably small propability).

This alone allows to fix the rate of GRBs to at least as rare as once per millenium.