Mysterious Gamma-Ray Burst May Be Linked To Gravitational Wave Find (latimes.com)

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Mysterious Gamma-Ray Burst May Be Linked To Gravitational Wave Find (latimes.com)

Posted by BeauHD on Monday April 18, 2016 @10:01PM from the mystery-machine dept.

mdsolar quotes a report from Los Angeles Times: After a decades-long search, scientists announced early this year that they had detected gravitational waves probably coming from the merger of two black holes back in September. Now, a team of scientists using NASA's Fermi Gamma-ray Space Telescope say they spotted a brief flash of gamma rays that occurred less than half a second after that long-sought gravitational wave signal. The gamma-ray outburst, described at the American Physical Society's April meeting in Salt Lake City, has not been definitively linked to that first gravitational wave signal, and scientists weren't able to pinpoint its exact origin -- just that they came from the same general area. But if other astronomers begin to find a similar pattern, the results do raise the intriguing possibility that such high-energy events might not be quite as 'invisible' as we thought. The first gravitational wave signal rolled through the Laser Interferometer Gravitational-wave Observatory on Sept. 14, hitting the Louisiana detector first and then the one in Washington state seven milliseconds later, telling researchers that the signal must have come from the southern hemisphere.

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"Half a second" is a lifetime... by Lisandro · 2016-04-18 22:13 · Score: 1

...when discussing gravitational or electromagnetic waves, isn't it?
1. Re:"Half a second" is a lifetime... by MichaelSmith · 2016-04-18 22:20 · Score: 4, Informative
  
  Yeah but photons are delayed when propagating through gas or plasma because they get absorbed and re-emitted. Photons from SN1987A arrived (IIRC) 14 seconds after the associated neutrinos.
  
  --
  http://michaelsmith.id.au
2. Re:"Half a second" is a lifetime... by Lisandro · 2016-04-18 22:21 · Score: 1
  
  Interesting, i'll have to read a bit more about that. Thank you!
3. Re:"Half a second" is a lifetime... by NotInHere · 2016-04-18 22:24 · Score: 5, Interesting
  
  This page has a possible explanation: http://www.universetoday.com/1...
  They say that the two black holes formed inside a giant star, and collapsed. This created both the gamma ray burst and the gravitational wave. Then the light needed to travel through the star's matter. While the gravitational wave can travel with the speed of light in vacuum, the light requires more time, that's where the .4 seconds delay comes from.
  They say also that in order for there being a gamma ray burst, there needs to be matter close to the colliding black holes. So this rules out a pair of black holes that orbited each other for a long time, because they would have cleared out the region.
4. Re:"Half a second" is a lifetime... by Anonymous Coward · 2016-04-18 22:25 · Score: 0
  
  ...when discussing gravitational or electromagnetic waves, isn't it?
  First of all, if you type part of your comment in the subject field you should repeat that part in the comment. Otherwise it becomes very inconvenient to quote the relevant parts of your comment.
  Half a second is a very long time with talking about electromagnetic waves in a lab, or on Earth at all.
  When talking about planetary distances it is still a fairly long time.
  On a galactic scale half a second is nothing.
5. Re:"Half a second" is a lifetime... by Anonymous Coward · 2016-04-18 22:30 · Score: 0
  
  Or photons come from the surface of a thing which could be on the order of a light second from the center....
6. Re:"Half a second" is a lifetime... by K.+S.+Kyosuke · 2016-04-18 22:37 · Score: 1
  
  In the SN1987A case, it was probably more a matter of things happening first inside the star and only then manifesting themselves on the surface. Or so I thought.
  
  --
  Ezekiel 23:20
7. Re:"Half a second" is a lifetime... by Anonymous Coward · 2016-04-18 23:21 · Score: 0
  
  Wait... I'm pretty sure this is not about absorption+reemittion as that scatters the photons and changes their energy state and such. It's more like how photons travel slower in a medium like glass than they do in a vacuum.
  Neutrons (and gravitation waves?) are not affected by the matter they pass through so gas and such in interstellar space will slow the photons, but not the others.
8. Re:"Half a second" is a lifetime... by angel'o'sphere · 2016-04-18 23:41 · Score: 1
  
  The light emitted inside of a star needs centuries if not millennia to reach the surface of the star.
  The matter is to dense and it bounces around extremely long.
  Or do you mean, formed long time ago and most of the star already gone?
  
  --
  Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
9. Re:"Half a second" is a lifetime... by Coisiche · 2016-04-19 00:13 · Score: 1
  
  Neutrons (and gravitation waves?) are not affected by the matter
  I think you mean neutrinos. Neutrons represent about half the mass of normal matter and don't pass through it easily. Gravity waves would theoretically be propagated by the graviton but since it's never been proven to exist it's hard to say what its attributes are.
10. Re:"Half a second" is a lifetime... by Anonymous Coward · 2016-04-19 00:14 · Score: 0
  
  You would think that if two black holes somehow existed within a star that most of the star would have already been absorbed by these bodies.
  Does anyone know what the Schwarzschild radius of the smallest possible black hole is? I'm sure there's a ton more that goes into this and no, I did not read the articles involved but I will be tonight when I have some free time. I'm just looking for a little insight by anyone who's really in the know on this matter.
11. Re:"Half a second" is a lifetime... by NotInHere · 2016-04-19 00:44 · Score: 3, Interesting
  
  Disclaimer: I am no physicist, I just read the papers and quote them :)
  There is this paper which does some speculation for what could have been the cause: http://arxiv.org/pdf/1602.0473...
  It says that the "hydrogen envelope" (probably most of the star), would be required to be ejected before the merger, otherwise it would choke the whole gamma ray burst already, meaning that we wouldn't have detected detect a gamma ray burst the first place if there was a hydrogen envelope. Probably something would have happened what happens right now in the sun, the "envelope" would convert the gamma ray radiation to lower frequency radiation, like visible light.
  So you might be right with most of the star being already gone when the event happened.
  The paper also tries to find an explanation on the cause for the delay:
  "For a progenitor star in the mass range [of 100 to 1000 solar masses], most of the observed 0.4 s delay can be accounted for by the neutrino cooling timescale or by the extra time it takes the GRB to jet to cross the star relative to GWs for a jet Lorentz factor of [gamma around 4-7]".
  I admit I can't really understand what they said here. The "neutrino cooling" is most likely cooling by neutrino radiation.
  But all references to neutrino cooling I could find in the paper indicate that this cooling is happening before the two black holes form, as a requirement for their formation, and not as an event between the BH merger and the GRB emission.
  Also I'm not sure what this has to do with a jet. I mean jets are these matter streams that leave an object at relativistic speeds (therefore also the Lorentz factor mention). But it is very unlikely that for the first GW we detect (GWs get emitted into all directions) we also detect a GRB emission which only gets to us because of a jet being targeted at us (something that affects only a tiny fraction of the star's sky), isn't it?
12. Re:"Half a second" is a lifetime... by Sique · 2016-04-19 00:55 · Score: 1
  
  From a purely theoretical point of view, a black hole could be of any mass, and thus the Schwarzschild radius could be of arbitrary size.
  A different question is what mass a star must have, so that after it lost all its ability to fusion atomic nuclei, it collapses into a black hole. As far as I remember, it was three sun masses. Such black holes are called stellar black holes. Stars lighter than that will end up as white dwarfs and finally as neutron stars.
  
  --
  .sig: Sique *sigh*
13. Re:"Half a second" is a lifetime... by secretsquirel · 2016-04-19 01:10 · Score: 1
  
  Could be wrong, but I believe that would be a plank length sized black hole.
14. Re:"Half a second" is a lifetime... by Anonymous Coward · 2016-04-19 02:25 · Score: 0
  
  neutron's *are* normal matter. comparing neutrons to normal matter makes no sense, as unspecified is what normal
  matter. the neutron and proton differ in mass by 1%.
15. Re:"Half a second" is a lifetime... by Anonymous Coward · 2016-04-19 02:50 · Score: 1
  
  Er, yes in a normal hydrodynamically stable star. In an event involving the kind of energy needed to create 2 black holes inside a star, or the kind of energy released via gravitational waves when 2 black holes somehow already existing inside a star merge, the star will be ripped apart in an instant and all those photons emitted very quickly. The typical light curve of a supernova happens over a matter of hours.
16. Re:"Half a second" is a lifetime... by Anonymous Coward · 2016-04-19 02:53 · Score: 0
  
  Read what he posted again. You're not disagreeing.
17. Re:"Half a second" is a lifetime... by Anonymous Coward · 2016-04-19 03:43 · Score: 0
  
  On a galactic scale half a second is nothing.
  Why? Does c vary with distance?
18. Re:"Half a second" is a lifetime... by Anonymous Coward · 2016-04-19 05:02 · Score: 0
  
  The theory that allows for any mass size (thus tiny) black holes is the same one that allows for infinite compression inside a black hole. Since we can't really look inside black holes, this is a pretty large assumption and people keep citing it as if it were well-established.
19. Re:"Half a second" is a lifetime... by Anonymous Coward · 2016-04-19 08:33 · Score: 0
  
  and the gamma radiation that does get get there would invariable come across some (albeit not much) gravitational influence as it bends slightly around a star for example. Whereas, the gravitational wave is essentially a shift in the entire makeup of space time all around it. It's immediate.
  This would seem to indicate cases where there is:
  
  a) a gravitational wave with a gamma ray burst or some other phenomenon in it's wake.
  because it's already been detected
  b) a gravitational wave with a gamma ray burst that is not detected.
  there could conceivably be a situation where a super massive black hole absorbs the gamma ray burst by being in the 'line of sight' of Earth.
20. Re:"Half a second" is a lifetime... by Anonymous Coward · 2016-04-19 08:48 · Score: 0
  
  >Wait... I'm pretty sure this is not about absorption+reemittion as that scatters the photons and changes their energy state and such. It's more like how photons travel slower in a medium like glass than they do in a vacuum.
  People keep saying that but a photon literally can't travel slower than c. That's really bothering me. Both facts cannot be true at the same time.
  The thing with photons travelling "slower" is just a classical approximation by averaging, isn't it?
21. Re:"Half a second" is a lifetime... by Anonymous Coward · 2016-04-19 13:08 · Score: 0
  
  Photons can't travel slower than c in a vacuum. Light can travel slower in a medium just fine, and it has to do with inducing currents and charges in the medium that partially cancel out the traveling wave, resulting in a wave that moves slower without any absorption or jumping. This happens to photons, although you get a messier situations where photons can couple to other stuff within the medium, and depending on the situation, end up with something like a plasmon where you have a combination of a photon and a phonon. In extreme cases, you get to BEC experiments, including ones where the photon can essentially become embedded in the medium, frozen in, then released later.
  The whole photons jumping from particle to particle thing just doesn't work, especially considering how in the x-ray & gamma region you can have index of refraction slightly lower than one. That doesn't mean faster than light travel, but gets into the difference between phase and group velocity. The idea of the photon jumping from atom to atom is just a false analogy, especially considering visible light has a wavelength larger than the separation between atoms in typical solids.
  If you want a more experimental answer, consider you can use different index of refraction material to create a consistent delay in photons within very sensitive systems, whereas jumping from particle to particle would result in a scatter and jitter of delays.
22. Re:"Half a second" is a lifetime... by manu0601 · 2016-04-19 16:04 · Score: 1
  
  photons are delayed when propagating through gas or plasma because they get absorbed and re-emitted.
  Even in vacuum, photons can hit quantum fluctuations and turn into an electron-positron pair. The pair quickly recombine into a photon with the same energy, but during the time the photon turned into matter, it travels at speed lower than light.
  Gravitational waves and neutrinos do not interact with vacuum quantum fluctuation this way. This is why they travel faster than photons. Their speed may be actual light speed, while photons travel slower than light speed (which is a bit odd when written like that, I agree).
23. Re:"Half a second" is a lifetime... by Anonymous Coward · 2016-04-19 17:06 · Score: 0
  
  Even in vacuum, photons can hit quantum fluctuations and turn into an electron-positron pair. The pair quickly recombine into a photon with the same energy, but during the time the photon turned into matter, it travels at speed lower than light.
  The observed properties of particles in QFTs already take vacuum effects into account. In other words, the speed of a photon is c after considering microscopic quantum fluctuations (and you can't have a photon turn into a macroscopic pair that can separate without the photon interacting with another particle due to momentum conservation anyway). The "true" speed of the photon without interacting with the vacuum is not measurable, and the propagator in QFT can go faster than light. Further more, neutrinos interact with the vacuum as does any other particle that falls under QFTs.
Not gravity waves... by Anonymous Coward · 2016-04-18 22:14 · Score: 0, Funny

It's God, banging his head against the universe after accidentally watching a Ted Cruz Ralley on Fox News...
1. Re:Not gravity waves... by Anonymous Coward · 2016-04-18 23:53 · Score: 0
  
  Or blowing his brains out after watching a Hillary rally... mission failure....
2. Re:Not gravity waves... by Anonymous Coward · 2016-04-19 00:14 · Score: 0
  
  No, they're definitely not gravity waves. Gravity waves aren't the same as gravitational waves. Gravity waves are a phenomenon in meteorology. In meteorology, we name waves by their restoring force. A wave displaces some volume of air (we'll call it a parcel) in some direction. In this case, we'll assume the wave pushes the parcel of air upward. If the atmosphere is unstable, that parcel of air will be less dense than its environment and will accelerate away from its original location; this happens in thunderstorms. But, if the atmosphere is stable, the parcel will be denser than its environment, and gravity will restore the parcel to its original location. That's why gravity is the restoring force, and why the wave is called a gravity wave. In reality, when a parcel is displaced upward in a stable environment, it will acquire downward momentum as it returns to its original location, and will actually overshoot the original level where it came from. When that happens, the parcel becomes less dense than its environment is pushed back to its original location and acquire upward momentum in the process. That process repeats, and that's how a gravity wave works.
  There are lots of gravity waves in the atmosphere; in the anvils of thunderstorms, downstream of mountain as stable air is forced over the mountains, and behind fronts and outflow boundaries at the top of the layer of cold air (these gravity waves have a particular name: undular bores). Look up gravity waves on Youtube and you'll find lots of neat videos. But gravity waves most definitely are not gravitational waves. They're two very different things and it frustrates me when people get that wrong.
3. Re:Not gravity waves... by Rockoon · 2016-04-19 00:59 · Score: 1
  
  It took God 7 days to create the universe because he was operating on C.P. time.
  
  --
  "His name was James Damore."
4. Re:Not gravity waves... by PopeRatzo · 2016-04-19 01:06 · Score: 1
  
  It took God 7 days to create the universe because he was operating on C.P. time.
  God operates on Tulsa time.
  https://youtu.be/hznfQSN1epM
  
  --
  You are welcome on my lawn.
5. Re:Not gravity waves... by Anonymous Coward · 2016-04-19 01:30 · Score: 0
  
  That's not how a wave works. A wave is a collective crowd gesture prevalent in sporting events, with many organizations worldwide claiming to be its originator. It's called a "wave" because everyone in the stadium makes a wave gesture. They don't call it "waves" because the effect is singular and it frustrates me when people get that wrong.
6. Re:Not gravity waves... by Anonymous Coward · 2016-04-19 03:09 · Score: 0
  
  I know you're making a joke. That said, I'd use the singular "wave" to describe one period, a crest and a trough. When multiple periods are involved, I'd use the plural "waves" to describe it. I don't expect that the ordinary person will actually know or care about the difference between gravity waves and gravitational waves. However, Slashdot isn't a community of ordinary people. Slashdot is a community of Nerds, who care about being accurate about science and technology. Besides, it's my one opportunity to contribute something meaningful to the discussion. :)
  Here are some videos of actual gravity waves:
  https://www.youtube.com/watch?v=CrplJBbUSZM
  https://www.youtube.com/watch?v=yXnkzeCU3bE
  https://www.youtube.com/watch?v=fMMMCCBIsXc
  That last one is a satellite loop; look over southern Nebraska and you'll see the overshooting tops of tornadic thunderstorms above the anvils. And then you'll see gravity waves coming off those overshooting tops.
7. Re:Not gravity waves... by Anonymous Coward · 2016-04-19 03:13 · Score: 0
  
  Why does God bang His noodly head in Germany so often? Did He aldented the coming election 30 million years ago? Or is He just a fan of German heavy metal music?
See what sending out them gravitational waves did, by turkeydance · 2016-04-18 22:24 · Score: 1

Moriarty? http://www.imdb.com/title/tt00...
More likely explanation by Anonymous Coward · 2016-04-18 22:26 · Score: 1, Insightful

I'm skeptical that gravitational waves have been detected. I'm a seismologist at a major west coast university and I've seen signals like this before. The most likely cause of the wave is a low amplitude s-wave moving north from seismic activity perhaps in the southern hemisphere. In the rush to find gravitational waves, it doesn't seem like the other, more plausible explanations have been ruled out.
1. Re:More likely explanation by Frans+Faase · 2016-04-18 23:01 · Score: 1
  
  Did not know that s-wave propegate with the speed of light.
2. Re:More likely explanation by Anonymous Coward · 2016-04-18 23:11 · Score: 0
  
  Coincidences propagate faster than light.
3. Re:More likely explanation by wonkey_monkey · 2016-04-18 23:14 · Score: 3, Insightful
  
  I had no idea seismology was such a covert field that you can't tell us which "major west coast university" you work at. Are you worried about receiving hate-mail from earthquake deniers?
  
  The most likely cause of the wave is a low amplitude s-wave moving north from seismic activity...
  ...at the speed of light?
  
  In the rush to find gravitational waves, it doesn't seem like the other, more plausible explanations have been ruled out.
  Just because they didn't explicitly state "oh, and by the way, it definitely wasn't s-waves, we checked", doesn't mean they haven't done their job. They'd be there forever if they had to list everything it definitely wasn't.
  
  --
  systemd is Roko's Basilisk.
4. Re: More likely explanation by Anonymous Coward · 2016-04-18 23:17 · Score: 0
  
  Also didnt know s waves chirped
5. Re:More likely explanation by MichaelSmith · 2016-04-18 23:48 · Score: 1
  
  So at what fraction of c do seismic waves travel? Can they go from Louisiana to Washington in 7ms?
  
  --
  http://michaelsmith.id.au
6. Re:More likely explanation by Anonymous Coward · 2016-04-18 23:56 · Score: 0
  
  I'm skeptical that gravitational waves have been detected. I'm a seismologist at a major west coast university and I've seen signals like this before. The most likely cause of the wave is a low amplitude s-wave moving north from seismic activity perhaps in the southern hemisphere. In the rush to find gravitational waves, it doesn't seem like the other, more plausible explanations have been ruled out.
  You don't think that LIGO would not have consulted with seismologists? I'm sure you can google for how they correct for such signals yourself or, if you are truly professionally interested and not just someone eager to show off their 'expertise' on slashdot - I would suggest getting in touch with them. I'm sure they would be happy to talk shop with a respected seismologist...
  That said - the fact that you claim to have seen seismic signals that travel at the speed of light indicates that you probably have not bothered to actually ready the details about this discovery.
7. Re:More likely explanation by Anonymous Coward · 2016-04-19 00:07 · Score: 0
  
  The "gravitational waves" were also detected at different times with a difference far greater than the speed of light, making me doubt their detection.
  Furthermore, the fallacy that you can isolate an EM beam of light from the planetary EM field is quite silly. A solar flare with its neutrinos, and charged particles (which have measurable and sometimes visible effects when interacting with the EM field of Earth), seems the most likely explanation.
  Captcha: Implying
  Indeed, captcha, implying gravity is real.
8. Re:More likely explanation by rgbatduke · 2016-04-19 01:02 · Score: 2
  
  ...at the speed of light?
  Um, not as a participant as I have no dog in either race, but you are confusing phase velocity and group velocity. If I shout in the middle of a room, detectors on both sides of the room can hear me at EXACTLY the same time. That doesn't mean that the sound wave went across the room at transluminal speeds.
  A seismic wave originating inside the Earth can easily be detected at the same time at two points separated by an arbitrary distance on the Earth's surface. In that case one inverts the argument and uses the time required for the wave to propagate to determine the likely origin inside the Earth, although it takes three detectors to triangulate it. If there were three LIGO detectors separated by a large baseline, we could do a lot better than say that the wave "came from the southern hemisphere" -- we could say that it came from some narrow cone overhead OR that it came from inside of the Earth.
  The gamma ray burst actually makes it a lot more likely, however, that the seismic explanation is incorrect, and one presumes that this is further bolstered by information obtained from the umpty-zillion seismographs scattered across the planet. Presumably they would have detected an S-wave earthquake event as precisely that, occurring at the same time, and with a comparatively precise interior location, and it would be very easy to determine that it was the probable cause of the LIGO signal. Granting the people who run LIGO simple competence and honesty, I'm pretty sure they ruled this out as ruling it out has to be standard operating procedure lest they call every single earthquake (of the dozens that occur in a day) a "gravitational wave". The GRB coincidence just rules it IN a bit more strongly.
  So no, it isn't the speed of light that is an issue here, as an S-wave that originated in just the right place could ripple across the surface much FASTER than light. It is almost certainly the lack of coincidence with detectors designed and utilized to detect S-waves, ruling out this sort of explanation.
  
  --
  Even when the experts all agree, they may well be mistaken. --- Bertrand Russell.
9. Re:More likely explanation by rgbatduke · 2016-04-19 01:13 · Score: 1
  
  Furthermore, the fallacy that you can isolate an EM beam of light from the planetary EM field is quite silly. A solar flare with its neutrinos, and charged particles (which have measurable and sometimes visible effects when interacting with the EM field of Earth), seems the most likely explanation.
  OK, I'm not sure what this even means, or what it has to do with the context of the top post or the reply, as a GRB is nothing at all like light produced by solar wind interacting with the planetary EM field -- you are off by a few orders of magnitude in energy scale and wavelength, for example, let alone spectrum. I realize, AC, that you are probably posting just to accomplish -- something -- but unless that thing is to confuse the reader, you might want to clarify. For example, my eyes are excellent detectors of the electromagnetic radiation field constituting a "beam of light" from all sorts of stars including the sun, reflected light from the moon, the light from the computer screen I'm working at. They effortlessly isolate it from the "planetary electromagnetic field", which isn't even light, generally speaking. Since I live far from the poles, light of the sort you seem to describe (the Aurora Borealis) is almost never seen at night so "isolating" starlight from it is absolutely trivial.
  Surely you know this -- or perhaps not, I don't know -- but granting you the benefit of the doubt, you need to make your point a lot clearer since nobody is talking about an EM beam of light in any part of the EM spectrum where there is the faintest chance of it being associated in any way with a solar event and/or the planetary field, unless you are asserting that the Sun itself exploded and we missed it. No? Then what?
  rgb
  
  --
  Even when the experts all agree, they may well be mistaken. --- Bertrand Russell.
10. Re:More likely explanation by Anonymous Coward · 2016-04-19 01:18 · Score: 0
  
  Assuming that it started somewhere in between the two, it could arrive at both at the same time.
11. Re:More likely explanation by avandesande · 2016-04-19 02:08 · Score: 1
  
  Not to mention that they check everything against local seismological data
  
  --
  love is just extroverted narcissism
12. Re:More likely explanation by Anonymous Coward · 2016-04-19 04:54 · Score: 0
  
  Sorry for being annon, don't want to undo moderation
  They checked, no speculation needed
  https://dcc.ligo.org/public/01...
  
  -Earthquakes
  can produce ground motion at the detectors with frequencies from approximately 0.03 to 0.1 Hz or higher if the epicenter is nearby [10]. R-waves, the highest amplitude component of seismic waves from an earthquake [11], are the most likely to adversely impact data quality by rendering the detectors inoperable
  or inducing low frequency optic motion that up-converts to higher frequencies in h(t) via mechanisms such as bilinear coupling of angular motion or light scattering. A network of seismometers installed at the LIGO detectors can easily identify earthquake disturbances.
13. Re:More likely explanation by cyberchondriac · 2016-04-19 04:54 · Score: 1
  
  What I can't get my head around is this: according to the summary, they spotted the gamma ray burst, which they claim occurred half a second after the first gravitational wave was detected. So.. is this suggesting that the gravitational wave exceeded the speed of light? But then, the gravitational wave is traveling slow enough that it takes a comparatively sluggish 7 msec to go from Louisana to DC? Maybe it's just the way the summary is written.
  
  --
  
  Look back up at my post, now look back down, you're on the Internet. Now look back up. I'm a signature.
14. Re:More likely explanation by Lord+Crc · 2016-04-19 05:37 · Score: 1
  
  In the rush to find gravitational waves, it doesn't seem like the other, more plausible explanations have been ruled out.
  Really? Did you read the paper[1]?
  
  High strain sensitivity also requires that the test masses have low displacement noise, which is achieved by isolating them from seismic noise (low frequencies) and designing them to have low thermal noise (intermediate frequencies). Each test mass is suspended as the final stage of a quadruple-pendulum system [56], supported by an active seismic isolation platform [57]. These systems collectively provide more than 10 orders of magnitude of isolation from ground motion for frequencies above 10 Hz.
  
  To monitor environmental disturbances and their influence on the detectors, each observatory site is equipped with an array of sensors: seismometers, accelerometers, microphones, magnetometers, radio receivers, weather sensors, ac-power line monitors, and a cosmic-ray detector[65].
  
  Exhaustive investigations of instrumental and environmental disturbances were performed, giving no evidence to suggest that GW150914 could be an instrumental artifact [69]. The detectorsâ(TM) susceptibility to environmental disturbances was quantified by measuring their response to specially generated magnetic, radio-frequency, acoustic, and vibration excitations. These tests indicated that any external disturbance large enough to have caused the observed signal would have been clearly recorded by the array of environmental sensors. None of the environmental sensors recorded any disturbances that evolved in time and frequency like GW150914, and all environmental fluctuations during the second that contained GW150914 were too small to account for more than 6% of its strain amplitude. Special care was taken to search for long-range correlated disturbances that might produce nearly simultaneous signals at the two sites. No significant disturbances were found.
  Emphasis mine.
  [1]: http://arxiv.org/abs/1602.0383...
15. Re:More likely explanation by Anonymous Coward · 2016-04-19 05:39 · Score: 3, Interesting
  
  So no, it isn't the speed of light that is an issue here, as an S-wave that originated in just the right place could ripple across the surface much FASTER than light. It is almost certainly the lack of coincidence with detectors designed and utilized to detect S-waves, ruling out this sort of explanation.
  Expanding on this a bit: for the S-wave to appear at both detectors with a plausible speed-of-light separation (i.e. a few milliseconds), it must have originated from a quite specific zone (somewhere on a hyperboloid running through the Earth, within a thickness of a few tens of metres). If an earthquake occurs somewhere in the Earth, it has maybe a 1-in-100,000 chance of being in that zone.
  If there were tens of thousands of suitable earthquakes per month, then this might still be a plausible explanation: it just so happened that one of these earthquakes hit the sweet spot to appear on both detectors within an interval resembling a light-speed travel delay. But that's not the case. After their standard processing of the data (which is meant to cut out earthquakes, instrumental problems, etc.), this burst was the *only* event which appeared on both detectors with this magnitude. So that leaves us with two possibilities:
  (1) An earthquake not only slipped through their processing (which is plausible), but also happened to occur in just such a position so as to fake a gravitational-wave signal, despite 1-to-100,000 odds against this (which is less plausible).
  (2) Gravitational waves.
16. Re:More likely explanation by MichaelSmith · 2016-04-19 22:53 · Score: 1
  
  But you said it was in the southern hemisphere.
  
  --
  http://michaelsmith.id.au
17. Re:More likely explanation by beastofburdon · 2016-04-20 05:49 · Score: 1
  
  citation needed.
Hey, don't tell me how to... by wonkey_monkey · 2016-04-18 23:10 · Score: 1

...post.

--
systemd is Roko's Basilisk.
1. Re:Hey, don't tell me how to... by PopeRatzo · 2016-04-19 01:04 · Score: 1
  
  ...post.
  ...(dumb as a...)
  
  --
  You are welcome on my lawn.
Magnetic reconnection? by mdsolar · 2016-04-19 00:01 · Score: 1

While blackholes have no hair, a pair of blackholes with different charges orbiting one another might. The merger might lead to a hair cut that leaves strands needing to resolve through reconnection in real space, causing pair production and destruction leading to gamma emission.
1. Re:Magnetic reconnection? by rgbatduke · 2016-04-19 01:24 · Score: 1
  
  Sure. Really, one can imagine a bunch of ways for there to be a GRB in association with a black hole collapse, up to and including them not quite being black holes, or one of them not being a black hole. Imagine a neutron star collapsing into a black hole, swirling around at lightspeed in its last fatal orbits with its magnetic field going nuts! Another very interesting possibility that one could probably infer from the spectrum, maybe, would be the effect of the gravity wave itself operating at very short range on a surrounding plasma cloud, exciting it so it basically gamma ray lased (really, coherence brightening along the outgoing track of compression caused by the gravity wave). This is the sort of thing one might be able to model -- gravitational wave creating a solitonic acoustical wave that lags very slightly and that is continuously brightened in the compressed region by stimulated emission as the plasma on the rear side of the soliton emits into the soliton itself. I think there are models for this sort of thing out there already -- something like this was once proposed as a possible mechanism to describe Quasars?
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  Even when the experts all agree, they may well be mistaken. --- Bertrand Russell.
2. Re:Magnetic reconnection? by mdsolar · 2016-04-19 02:55 · Score: 1
  
  There is a new MNRAS paper on reconnection in grbs http://arxiv.org/abs/1509.0219... but what I'm thinking of is a sulution to a lack of plasma around a black hole pair. The orbits are all unstable so matter should be consumed prior to merger. What then emits light? Magnetic reconnection can produce a pair plasma, and on a large enough scale, it might be Compton thick (briefly). You might end up with an isotropic (ish) burst as the plasma decays....
3. Re:Magnetic reconnection? by rgbatduke · 2016-04-19 03:39 · Score: 1
  
  Sure, but in the vicinity of the galactic center there could easily be a steady supply of infalling "stuff" -- maybe it was a three star system and a supergiant was feeding the pair of black holes as they were spiralling into one another, for example. So it is hard to rule out a surrounding plasma gas on the basis of a simple model, the assumption of completely isolated BHs, or the no-hair rule. Remember, the only way we can sort-of-observe black holes directly at all (e.g. Cygnus X-1) is by the x-rays given off by infalling plasma, so it is pretty hard to claim that black holes are never surrounded by an infalling plasma. The interesting question is whether or not a gravity wave can carry enough energy to actually compress infalling stardust maintained as a plasma by the x-rays emitted by the infalling stuff to produce a coherence brightened pulse at all, or (equally interesting) to cause a possible neighboring supergiant to go nova as it swept across its fusion core. THAT would be some interesting "amplification", although the lag doesn't seem long enough for that to be plausible.
  It's all just games (I'm a theorist myself and love to play) without any real data... and I doubt that the observational data is up to the task of differentiating the possibilities very cleanly when we cannot be certain that the two are even causally connected instead of being a coincidence. We really need triangulation, not just two LIGO sites, to at least create a MODERATELY narrow cone of possible directions instead of a very wide one indeed.
  
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  Even when the experts all agree, they may well be mistaken. --- Bertrand Russell.
4. Re:Magnetic reconnection? by mdsolar · 2016-04-19 04:19 · Score: 1
  
  Suspect a gravity sandwich would have little delay in detections. You are right that LIGO expansion will help.
5. Re:Magnetic reconnection? by beastofburdon · 2016-04-20 05:52 · Score: 1
  
  Magnetic reconnection is about as scientific as Noah's Ark. Actually, I think the Ark is more plausible.
6. Re:Magnetic reconnection? by mdsolar · 2016-04-20 06:19 · Score: 1
  
  Some aspects are discussed here: http://iopscience.iop.org/arti...
7. Re:Magnetic reconnection? by beastofburdon · 2016-04-20 06:33 · Score: 1
  
  The guy that came up with it in the first place later said that it was complete bullshit. Sadly, nobody listened that time.
8. Re:Magnetic reconnection? by mdsolar · 2016-04-20 22:15 · Score: 1
  
  Do you have a link?
9. Re:Magnetic reconnection? by beastofburdon · 2016-04-21 02:17 · Score: 1
  
  I can't seem to find the article I read that in, but I did find a good explanation as to why the theory does not work.
  https://www.libertariannews.or...
  This goes over the theory and many of its problems in a fairly easy to understand manner. Well, easy if you have a decent understanding of electricity and magnetic fields anyway.
10. Re:Magnetic reconnection? by mdsolar · 2016-04-21 06:57 · Score: 1
  
  I'll try to read all of it, but it contains basic conceptual errors at the beginning, so I doubt it will be ultimately persuasive.
11. Re:Magnetic reconnection? by mdsolar · 2016-04-22 14:34 · Score: 1
  
  It was very long and seemed confused. I'll just say the insisting on lab conditions probably gets him off on a false start. Plasmas don't require electric input to exist. They can be created by collisions or photo excitation or pressure or just the tearing of spacetime. EMP is a manifestation of the resistance he later claims does not exist. As a rule of thumb, stuff that says engineers know what scientists don't when talking about science is usually screwball.
12. Re:Magnetic reconnection? by beastofburdon · 2016-04-26 02:26 · Score: 1
  
  If magnetic reconnection existed we would have small explosions every time two electric motors moved in relationship to each other. The entire idea is science fiction.
A mere coincidence. by Anonymous Coward · 2016-04-19 00:43 · Score: 0

It was actually me trying really hard to hulk out. I knew it would eventually start working! Now mom will stop making fun of me. Ok I need to get back to practicing!
Most Likely Explanation by Tenebrousedge · 2016-04-19 01:27 · Score: 1, Informative

The most likely explanation was that it was just a spurious signal (as your source notes). Quoting Wikipedia:

However, observations using the INTEGRAL telescope, through the all-sky SPI-ACS instrument, indicate that the amount of energy in gamma-ray and hard X-ray emission from the event was less than one part in a million of the energy emitted in the form of gravitational waves, concluding that "this limit excludes the possibility that the event is associated with substantial gamma-ray radiation, directed towards the observer." If the signal observed by the Fermi GBM was genuinely astrophysical, SPI-ACS would have detected it with a significance of 15 sigma above the background.[50] The AGILE space telescope also did not detect a gamma-ray counterpart of the event.[51]
It's also worth noting that while Fermi can tell the origin of a signal to some degree, it's not what you would call pinpoint accurate. "The region not occulted by the Earth contains 75% of the probability of the localization map," which means that the other 25% was pointing towards a terrestrial gamma ray burst but that's not what we're here to science, darn it! Later they say, "The best-fit location is towards the Earth but the large uncertainty on the location allows an arrival direction from the sky."
This event has consumed ink wildly out of proportion to its merit.

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Those who advocate genocide deserve every protection afforded by law, and none afforded by common human decency.
1. Re:Most Likely Explanation by Anonymous Coward · 2016-04-19 07:04 · Score: 0
  
  This event has consumed ink wildly out of proportion to its merit.
  As usual these days.
Oral Roberts by number6x · 2016-04-19 03:34 · Score: 1

Speaking of Tulsa...
Oral Roberts passed away and was waiting in line at the pearly gates. As he approached, St. Peter, not looking up from the parchment he was writing names in with a long quill, asked for his name. The newly departed reverend replied 'Oral Roberts' sir.
St. Peter paused, and looked up with a look of astonishment and joy.
St. Peter asked: 'The Oral Roberts?'
Oral Roberts:'Yes.'
St. Peter: 'Of Tulsa, Oklahoma?'
Oral Roberts:'Yes.'
St. Peter said to those still in line: 'I have to take this man inside heaven immediately, please wait patiently for a few minutes.', and to Oral, St. Peter said 'Please, follow me Rev. Roberts, there is someone I must take you to see.'
As they were walking into heaven they passed by Moses, the prophet. St. Peter told Moses who the newly arrived soul was. Moses' face lit up with joy and happiness, and Moses turned to Rev. Roberts and asked: 'Are you really The Oral Roberts?'
Oral Roberts:'Yes.'
Moses: 'Of Tulsa, Oklahoma?'
Oral Roberts:'Yes.'
Moses continued by saying that there was someone who truly needed to see Roberts as soon as possibly, so Moses, St. Peter and the bewildered Roberts continued on. Shortly they came near a young man preaching to a small crowd. Moses and St. Peter waived to get the young man's attention. The young man saw them and asked the crowd if they would excuse him for a few minutes, it looked as if he was needed elsewhere. As the young man approached, both Moses and St. Peter started calling out: 'Jesus, Jesus, you'll never guess who just arrived. This is Oral Roberts!'
Jesus' face broke into a broad smile, as he could barley hold back the joy inside him.
Jesus said excitedly: 'Are you really The Oral Roberts?'
Oral Roberts:'Yes.'
Jesus: 'Of Tulsa, Oklahoma?'
Oral Roberts:'Yes.'
Jesus informed the Rev. Roberts that there was someone who had been waiting to meet him for a long time, and that they should all hurry. The four continued on into the heart of heaven.
As they approached the center of heaven Oral Roberts grew astonished, and a little frightful. They approached the throne at the very center of heaven and upon the throne was god himself. The four came to the throne, reverentially, and Jesus said: 'Father, there is someone here that I would like you to meet, Oral Roberts!
God shifted a little in his seat of power to look upon the foursome at the foot of his throne, and in doing so his face went from calm to a grimace of pain. It was momentary, but undeniable. Oral Roberts grew frightened at the sight. but soon he saw the pain pass, and saw god's face light up with a love and joy more pure than he had ever experienced in his former life in the mundane world.
God asked:The Oral Roberts?'
Oral Roberts:'Yes.'
God: 'Of Tulsa, Oklahoma?'
Oral Roberts:'Yes.'
God leaned forward in his throne, once again grimacing in pain with the movement, and said: 'Oh, Rev. Roberts, I've been waiting so long for you. I have this pain in my lower back and was wondering if you could help me...'
We need 2 more gravity sensors by Anonymous Coward · 2016-04-19 03:53 · Score: 0

If we had a tetrahedron, then we could see the direction the event came from.
Gravitational waves linked to Chuck Norris workout by zero_out · 2016-04-19 04:54 · Score: 1

Gravitational waves are the result of Chuck Norris doing push-ups. All this "gamma ray" stuff is just Chuck Norris deniers grasping at straws.
Incredible by Anonymous Coward · 2016-04-19 06:54 · Score: 0

An article about gamma rays and no comments about Bruce Banner or his green friend? I'm disappointed.
Even more likely explanation by Anonymous Coward · 2016-04-19 10:00 · Score: 0

Based on the actual paper, and your response, you're a fucking embarrassment.
I find it highly unlikely that are even a real seismologist and more likely a student who is enrolled in a course on the subject.
Building upon the retracted... by beastofburdon · 2016-04-20 05:54 · Score: 1

This gravitational wave garbage has already been retracted for months now.
http://www.forbes.com/sites/pa...
http://www.nature.com/news/no-...