An artist's impression of a Gamma Ray Burst. Credit: Stanford.edu

Did a Gamma Ray Burst Accompany LIGO’s Gravity Wave Detection?

18 Feb , 2016 by

Last week’s announcement that Gravitational Waves (GW) have been detected for the first time—as a result of the merger of two black holes—is huge news. But now a Gamma Ray Burst (GRB) originating from the same place, and that arrived at Earth 0.4 seconds after the GW, is making news. Isolated black holes aren’t supposed to create GRB’s; they need to be near a large amount of matter to do that.

NASA’s Fermi telescope detected the GRB, coming from the same point as the GW, a mere 0.4 seconds after the waves arrived. Though we can’t be absolutely certain that the two phenomena are from the same black hole merger, the Fermi team calculates the odds of that being a coincidence at only 0.0022%. That’s a pretty solid correlation.

So what’s going on here? To back up a little, let’s look at what we thought was happening when LIGO detected gravitational waves.

Our understanding was that the two black holes orbited each other for a long time. As they did so, their massive gravity would have cleared the area around them of matter. By they time they finished circling each other and merged, they would have been isolated in space. But now that a GRB has been detected, we need some way to account for it. We need more matter to be present.

According to Abraham Loeb, of Harvard University, the missing piece of this puzzle is a massive star—itself the result of a binary star system combining into one—a few hundred times larger than the Sun, that spawned two black holes. A star this size would form a black hole when it exhausted its fuel and collapsed. But why would there be two black holes?

Again, according to Loeb, if the star was rotating at a high enough rate—just below its break up frequency—the star could actually form two collapsing cores in a dumbbell configuration, and hence two black holes. But now these two black holes would not be isolated in space, they would actually be inside a massive star. Or what was left of one. The remnants of the massive star is the missing matter.

When the black holes joined together, an outflow would be generated, which would produce the GRB.  Or else the GRB came “from a jet originating out of the accretion disk of residual debris around the BH remnant,” according to Loeb’s paper. So why the 0.4 s delay? This is the time it took the GRB to cross the star, relative to the gravitational waves.

It sounds like a nice tidy explanation. But, as Loeb notes, there are some problems with it. The main question is, why was the GRB so weak, or dim? Loeb’s paper says that “observed GRB may be just one spike in a longer and weaker transient below the GBM detection threshold.”

But was the GRB really weak? Or was it even real? The European Space Agency has their own gamma ray detecting spacecraft, called Integral. Integral was not able to confirm the GRB signal, and according to this paper, the gamma ray signal was not real after all.

As they say in show business, “Stay tuned.”

 

 

 

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space_cookie
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space_cookie
February 18, 2016 6:00 PM

GBM = Gamma-ray Burst Monitor (one of the instruments on the Fermi Gamma-ray Space Telescope).

Stephen Farrugia
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Stephen Farrugia
February 23, 2016 7:29 AM

Has this phenomenon generated neutrinos that were detected?

btraymd
Member
btraymd
February 19, 2016 12:45 AM
There are some very basic problems with this “gravity wave detection” pronouncement. First, no one has adequately described the exact nature of gravity. It is a force with a source that has not been identified. So how can it be determined that it exists in wave form? What was actually detected and does it shed light on the fundamental nature of gravity? Secondly and of great importance is the very concept of a “black hole” as put forth by the “standard model”. There are some growing problems with this model. Recent radio telescope data seems to contradict the model or at least confirms data that the model cannot explain. First of all we now know that “black holes”… Read more »
Jeffrey Boerst
Member
February 19, 2016 1:55 AM
Using quotation marks like that is not only grammatically incorrect, it’s a sign of belittling something which means you need all the help you can get demeaning it. And considering the dearth of them flying around your little diatribe, you’re really desperate to appear correct. You’re wrong. It happened and exactly how it was predicted to look 101 years ago. GWD = lights out for the electric universe, though that’s actually been the case for a few decades now for the enormous percent of us not weasily fooled by hucksters. (BTW, using lower case letters like I did just there is another form of belittling. Only I’m doing it to because it’s fun) “This enormous “””””discovery””””” and the… Read more »
redmudislander
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redmudislander
February 19, 2016 9:26 PM

” . . . considering the dearth of them flying around . . . ”

Scratch “dearth”, and insert “plenitude”, and you’ll make a better rebuttal.

Look them up first. (if necessary)

mewo
Member
mewo
February 19, 2016 3:34 AM
Do you really not understand that the gamma rays and jets from a black hole actually originate from the matter in the accretion disk orbiting it? I explained this to you last time you slammed us with your copy-pasted wall of idiotic text. Weren’t you paying attention? It’s funny that you would accuse scientists of rejecting observation, theory, and experiment. It’s almost as though you don’t know what LIGO is and does. But your complete lack of comprehension of anything is well known around here. In previous discussions we’ve found out that you’re actually profoundly ignorant of electric and magnetic phenomena. For instance, you did not understand such high school basics as the fact that a rotating charged… Read more »
Aetzbar
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Aetzbar
February 19, 2016 6:24 AM
Secrets of the Universe In the beginning was infinite geometric space. This space became filled with Static Time at absolute rest and absolute cold. Static time is strictly quantitative, and does not differentiate between past, present and future. Being quantifiable and measurable, static time is a scientific concept. Static time of 0.0033 microseconds per meter will be measured regardless of the direction chosen. Stars move through static time, which does not disrupt their motion. Static time exists but is imperceptible. Static time is the deepest secret of the universe. Static time fills all infinite space, eliminating the possibility of a vacuum. Static Time Waves (STW) travel through static time. The speed of STW is 300,000 km/second. Aetzbar in… Read more »
Steven
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Steven
February 19, 2016 1:26 PM

Has anyone ever modeled a spinning star breaking into two cores before?

Might this be relevant to Eta Carinae which is said to be near it’s limit of spin rate?

redmudislander
Member
redmudislander
February 19, 2016 9:29 PM

@ Jeffery B.
Scratch “dearth”, and insert “plenitude” and you’ll have a better argument.
Look them up.

Dan
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Dan
February 20, 2016 11:55 AM

I have a very naive question. Isn’t it possible that there is some body blocking the path of gamma rays to us but neutrinos go through it just as they always like to do?

Potatoswatter
Member
Potatoswatter
February 21, 2016 3:58 AM

Yes, neutrino bursts are observed before the visible light of supernovas. However, black hole mergers don’t produce neutrinos as far as I know. Neutrinos result from nuclear reactions.

Other events might produce both. It would be exciting to triangulate a position from both non-EM observations, then point a telescope and watch it happen!

Also, gravitational waves (as far as I know) travel at exactly the speed of light, but neutrinos are merely relativistic. Looking at the delay between the GW and neutrino waveforms could help estimate neutrino mass.

Zoutsteen
Member
Zoutsteen
February 21, 2016 12:09 PM

I don’t mind being skeptical about the GW
Or being more skeptical with this news.

But that is more because LIGO has tried a long time to observe a signal
And the scientific papers it produced so far, belong more in the realm of hypothetical alternatives.

The silliest I can think of is the planar alignment of the 2 BH’s vs GRB vs the observed GW & GRB

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