"Creation of Black Hole Detected"
It should be noted that the double neutron star explanation for this event is extremely speculative at this point.
Why? I think that is a compelling observation. Seriously, what are the objections? That interpretation seems like a good fit to me.
Based on what? All I see is a quote from an astronomer saying, "This really does look like a merger scenario." As far as I know, there's no paper on the subject.
Your arguments are compelling. And I don't mind a good argument. And it's not like I think I am some kind of expert on anything [definitely not]. Still I am influenced by other reads:
2S 0921-630 1.90+-0.25 Msun (1 sigma errors)
2S0921-630 2.0-4.3 Msolar (1-sigma)
Neutron Star Mass Measurements. I. Radio Pulsars
Authors: S. E. Thorsett (Princeton University), Deepto Chakrabarty (MIT)
Perhaps I am quoting irrelevant papers. Wouldn't be the first time.
Can you explain why you think they're relevant? I'm not really seeing the point. I don't doubt the existence of neutron star binaries and certainly not of neutron stars themselves. I also don't doubt that we see things that are either black holes or something not explained by GR. All I'm skeptical of is the neutron star merger explanation for this particular event. It only happened two days ago, so there's no way to confirm their analysis.
Regardless of the exact nature of the event, looks like that Swift scope is living up to its billing. Cool stuff.
Is there any past paper predicting what a neutron-binary merger would look like? Has anyone published an analysis which predicted that such a merger could/would look like a GRB + visible flash?
It sounds like the scientist quoted has indeed read (or written?) such a paper:
'"A fraction of a second before contact, the lower mass neutron star is disrupted and forms a neutrino driven accretion disk around the higher mass neutron star," Sigurdsson told SPACE.com. "It implodes under the weight and forms a maximally spinning low-mass black hole."To me, this doesn't sound like off-the-cuff speculation.
more about this and other GRB
Here's a picture of it
posted at Josh Bloom's site
Here's Sean Carroll's blog about it
There is much literature on the merger of neutron stars resulting in a GRB; in fact, I worked in the same department as Peter Meszaros, the father of the relativistic fireball model. However, there is also a lot of literature on other processes producing GRBs, as well as observational evidence supporting their association with other events (like supernovae). What I'm saying is that these quotes haven't been presented formally or put through peer review, so we shouldn't be just taking them as fact. They might be right, but you simply can't tell from that article.
Fair point, thanks.
While we're on the topic, may I pick your brain a little?
The article mentions that it was a "short duration" GRB. What other distinguishing characteristics do GRBs have? Do they tend to cluster into well-defined categories, or is there a fairly flat spread on most characteristics?
It turns out that GRBs have a bimodal distribution in duration, meaning basically that there are two types: long bursts and short bursts. The fact that they come in two types implies that there may be multiple physical processes that can produce them, so if this actually were a merger event, that wouldn't necessarily be inconsistent with the recent correlation between GRBs and supernovae. Up to this point, we've been unable to study the short-duration bursts (< 2 seconds) very well because they would be over long before we could point our other telescopes at them.
Just to amplify one phrase in ST's post: "there may be multiple physical processes that can produce them"
While the accumulating observational data is beginning to provide good tests of models for (some of) the long duration bursts, until this Swift GRB, there was essentially nothing to contrain models of short durations bursts (other than their isotropy and the gamma light curve and spectrum).
And one shouldn't be too sanguine about the view that long bursts originate via essentially one mechanism either - why so many remain 'dark' (no detected optical afterglow) and how to account for the variation among GRBs with well observed X-ray, optical, IR, ... afterglows may be telling us more than one mechanism can produce long bursts!
The existence of two or more processes that lead to gamma-ray bursts would be quite amusing, I think, considering that the community had such a hard time believing that any extragalactic process could produce the observed bursts.
Interesting. Do we know if Ligo should be able to detect the gravity waves from this event yet? If the necessary number of detectors were up, this seems like a good candidate for gravitaitonal wave detection.
Stranger things have happened!
How many 'Cepheid period-luminosity' relationships are there? How many types of 'supernova standard candles' are there? How 'clumpy' was 'interstellar reddening' before IRAS?
Yeah, I'm not saying it would surprise me, I'm saying it would be funny.
It was much too far away to be detectable. Of course people checked anyways, but there wasn't anything in the data.
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