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Paracelsus
2007-Aug-26, 07:29 PM
Via SciAm online: http://blog.sciam.com/index.php?title=hints_of_a_breakdown_of_relativity _theor&more=1&c=1&tb=1&pb=1


The MAGIC gamma-ray telescope team has just released an eye-popping preprint (following up earlier work) describing a search for an observational hint of quantum gravity. What they've seen is that higher-energy gamma rays from an extragalactic flare arrive later than lower-energy ones.

The team studied two gamma-ray flares in mid-2005 from the black hole at the heart of the galaxy Markarian 501. They compared gammas in two energy ranges, from 1.2 to 10 tera-electron-volts (TeV) and from 0.25 to 0.6 TeV. The first group arrived on Earth four minutes later than the second. One team member, physicist John Ellis of CERN, says: "The significance of the time lag is above 95%, and the magnitude of the effect is beyond the sensitivity of previous experiments."

The original paper is here: http://arxiv.org/abs/0708.2889

I'm not clear on why these results imply the effects of quantum gravity. The blog entry says that the authors ruled out difference in timing of release of the higher energy gamma-rays vs. lower-energy gamma-rays as a cause of the time delay.

Ken G
2007-Aug-26, 07:32 PM
Yeah, that doesn't sound like it has anything at all to do with quantum gravity, the energies are nowhere close to Planck scales. It instead sounds like a challenge to basic relativity, the only one I've heard of in a long time-- but my money is still on error in observational interpretation.

publius
2007-Aug-26, 08:02 PM
In the paper, they state that while one might expect the energies required to be near the Planck mass, some theories suggest the threshold might be smaller. I have no clue what to think about it. :)

If these observations are accurate, then we do have a breakdown of the Equivalence Principle, something that many expect to happen with quantum gravity.

-Richard

Ken G
2007-Aug-26, 10:40 PM
But why is the energy uncertain? The gamma rays have to be detected, and the highest energy gamma ray I've ever heard of being detected is 3 times 10 to the 20 eV. That's nowhere close to the Planck scale (10 to the 28 eV)-- such high energy photons are not even thought to be able to propagate through the CMB without interacting.

publius
2007-Aug-27, 04:16 AM
Now, I know as much about this as I do brain surgery, but according to that paper the idea is one gets a vacuum "refractive index" due to quantum space-time fluctuations of:

r ~ 1 - (E/M_QGn)^n, where n looks like some quantum number thingy. Why that is 1 minus and not 1 plus I don't know, but that's how they put it, and the M_QGn's are the mass threshold.

The say their results constrain M_QG1 > 0.4 *10^18 GeV, and the
M_QG2 > 0.4 *10^11 GeV. That's still pretty high. I don't understand the 'n' progression, and why it would get lower.

It says string theories and some extra dimensional theories will let the M_QG's be less than the Planck mass.

-Richard

Ken G
2007-Aug-27, 05:30 AM
I guess the idea is that even though our observations are at least a billion times below the Planck scale, the propagation times are very long and the difference in arrival times could be measurable even if there is just a hint of Planck-scale influence. It's provocative, that's for sure. What bothers me about it is that if you are a billion Bohr radii from a proton that's like a centimeter, so this is like trying to probe the nature of a hydrogen atom by watching electrons that pass a centimeter away from the proton! How do we know how much physics we're missing there? Still, I realize that any confirmed depature from the equivalence principle is probably a Nobel prize.

trinitree88
2007-Aug-27, 06:35 AM
Yeah, that doesn't sound like it has anything at all to do with quantum gravity, the energies are nowhere close to Planck scales. It instead sounds like a challenge to basic relativity, the only one I've heard of in a long time-- but my money is still on error in observational interpretation.

KenG. Although flare gamma ray emission is not identical to classical GRB's, there's a history there. Most GRB's begin as "hard"...>300 kev...bursts, and then attenuate to "softer"..<300 kev fluences. But it is not always the case. (see section 9d in the link).
There are at least some bursts that begin with soft (the authors will call it NHE...non hard energy) fluence, and then switch to hard (HE, their designation)..fluence. They also find that single sources are capable of both types of fluences within a single burst, or that repeat bursts may be only of a single mode (HE or NHE) without contamination of the other. So, if a physical mechanism exists for inverted mode emission in classical GRB's, can it be ruled out entirely in a Markarian flare emission, too? Can a pair of isolated soft (NHE) followed by hard (HE) bursts occur within a four minute time frame?...seems like thin statistics to claim a failing of relativity here, based on this sole event. pete.

see:http://www.journals.uchicago.edu/ApJ/journal/issues/ApJ/v489n1/35715/35715.html#fg9

Ken G
2007-Aug-27, 09:41 AM
Yeah, it sounds like the kind of result you'd have to already be expecting in order to believe that interpretation. Not that I could say one way or the other.

Nereid
2007-Aug-27, 01:17 PM
But why is the energy uncertain? The gamma rays have to be detected, and the highest energy gamma ray I've ever heard of being detected is 3 times 10 to the 20 eV.
[snip]Those are UHECRs (ultra-high energy cosmic rays), mostly likely protons, but perhaps nuclei (up to) iron - it's kinda difficult to determine the composition of these very rare beasts.

The highest gammas that I can recall being reported are ~20 TeV, from an innovative CR 'telescope' (whose name escapes me just now), which uses water instead of air.

When (if?) LOFAR is up and running, it should provide some nice independent checks on this.

However, I think the second part of the last sentence of the (pre-print) abstract is the most important: "but we cannot exclude the importance of some other source effect" - the source is a physical regime so far from anything probed so far in any Earthly lab (and likely to remain unprobed for possibly centuries to come) that constraining 'source effects' will likely be a headache for many decades yet.

Ken G
2007-Aug-27, 01:51 PM
The highest gammas that I can recall being reported are ~20 TeV, from an innovative CR 'telescope' (whose name escapes me just now), which uses water instead of air.
Good point, that's ten million times lower than even 10^20 eV, so farther still from the Planck limit. But even more puzzling-- now they are talking about probing the Planck limit with photons that whose energies are 15 orders of magnitude smaller than where the real action is. Hardly an ideal way to test a theory!

the source is a physical regime so far from anything probed so far in any Earthly lab (and likely to remain unprobed for possibly centuries to come) that constraining 'source effects' will likely be a headache for many decades yet.
Yes, observational interpretation will probably always be the main stumbling block, except for those already predisposed to favor some particular quantum gravity theory (who will cite this result ad nauseum, no doubt!).

antoniseb
2007-Sep-09, 03:59 PM
This (http://www.newscientist.com/article/dn12609-finally-a-magic-test-for-string-theory.html) preview of a proprietary New Scientist article gives an interesting hint about something that may be important.

The idea as I understand it is that very high energy gamma rays may travel more slowly than lower energy ones due to the non-linear paths they take through the quantum foam (or some other such explanation).

Up till now, this has never been observed, but MAGIC looks at a *very* high range in the energy spectrum. A flare was observed in Markarian 501, and the super-high energy photons arrived four minutes late.

Does anyone have a link to an arXiv paper on this, or MAGIC press release?

If this is true, this is strong evidence for some flavor of String theory to be on the right track.

publius
2007-Sep-09, 04:56 PM
Paracelsus posted about this in Q&A:

http://www.bautforum.com/questions-answers/63917-breakdown-relativity.html

The link to the arxiv paper is there. If this is true, then we have indeed observered a breakdown of the Equivalence Principle, and are seeing a quantum gravity effect.

This is something that is consistent with a quantum gravity effect, but isn't a smoking gun. We're talking needle in a haystick type of stuff, a difference in time of minutes compared to total times of millions of years (or whatever it is, pretty big). There could be some other mechanism there. It's darned interesting, but let's don't get too excited yet.

-Richard

Tim Thompson
2007-Sep-09, 11:50 PM
This topic came up in the ATM forum as well: New Evidence for Tired Light (http://www.bautforum.com/against-mainstream/64413-new-evidence-tired-light.html). I review the paper in that thread (post #5 (http://www.bautforum.com/1066962-post5.html)). I think that the New Scientist article, and the blog piece posted in ATM both seriously exaggerate the significance of the observations.

Nereid
2007-Sep-10, 12:00 AM
This topic came up in the ATM forum as well: New Evidence for Tired Light (http://www.bautforum.com/against-mainstream/64413-new-evidence-tired-light.html). I review the paper in that thread (post #5 (http://www.bautforum.com/1066962-post5.html)). I think that the New Scientist article, and the blog piece posted in ATM both seriously exaggerate the significance of the observations.For the record: a BAUT member posted an explicit reference to that ATM thread, along with an unambiguous ATM claim (which goes way beyond what's in the relevant preprint), here in this thread. That post has been removed, and the case is under review with regard to promotion of ATM claims outside the ATM section.

As this topic is already the subject of a Q&A thread (as publius mentions), this one is closed. Please continue discussion in Breakdown of relativity? (http://www.bautforum.com/questions-answers/63917-breakdown-relativity.html)

The two threads will be merged shortly.

[ETA: Threads now merged.]

antoniseb
2007-Sep-10, 05:13 PM
Good point, that's ten million times lower than even 10^20 eV, so farther still from the Planck limit.

Having looked at the paper, I'm possibly misreading it as saying that the deviation from c is proportional to the energy divided by the Planck mass, or it is proportional to the square of that same ratio. This is one data point, so you can draw any line you like through it, but the implication is that the deviation is linearly proportional, and at a few TeV, is enough to provide a 240 second delay over a 140 quadrillion second flight (roughly a part in 1015).

I think that there will come a time in the near future when MAGIC, or a similar installation, will have observed similar flares from a different more distant BL Lac object, and the numbers will be more clear.

As a first observation of this sort, this is very exciting news.

Ken G
2007-Sep-10, 06:15 PM
I agree, it is potentially Nobel prize stuff here. What I find so interesting is that we have, in effect, a way to measure a time difference with 10-15 precision, simply by having a "fast" process that happened a "real long time" ago! If you have a process that is going on all the time, you want to give it plenty of time to happen, so you look at something very bright and very far away.

Jerry
2007-Sep-10, 06:35 PM
I think they are flying blind here. Too much is not known about the sources of Gamma Rays to run very far with this. As Neried observed in the abstract the authors caution, "We cannot exclude the possibility that the delay we find, which is significant beyond the 95% C.L., may be due to some energy-dependent effect at the source."

The authors are looking at one of many possible reasons the energy peaks in different wavelengths at different times. Without a good physical mechanism that explains exactly how theses events originate, it is difficult to weigh-in on how the energy should be expected to be distributed.

Ken G
2007-Sep-10, 07:32 PM
But those kinds of issues will emerge more clearly with more data. It sounds like a promising avenue, that could reap real rewards if the delay scales with distance.

Nereid
2007-Sep-10, 07:43 PM
If this preprint results in lots more attention being paid to GRBs, to a speed up of the installation of LOFAR (http://www.lofar.org/) (and the building of another half dozen or so, in different locations), of Milagro (http://umdgrb.umd.edu/cosmic/milagro.html) (ditto), etc ... then it will have been a fantastic paper ... even if (as I think likely) nothing about quantum gravity emerges at the end of the day.

Nereid
2007-Sep-11, 12:13 AM
Study of time lags in HETE-2 Gamma-Ray Bursts with redshift: search for astrophysical effects and Quantum Gravity signature (http://arxiv.org/abs/0709.1132):
The study of time lags between spikes in Gamma-Ray Bursts light curves in different energy bands as a function of redshift may lead to the detection of effects due to Quantum Gravity. We present an analysis of 15 Gamma-Ray Bursts with measured redshift, detected by the HETE-2 mission between 2001 and 2006 in order to measure time lags related to astrophysical effects and search for Quantum Gravity signature in the framework of an extra-dimension string model. The use of photon-tagged data allows us to consider various energy ranges. Systematic effects due to selection and cuts are evaluated. No significant Quantum Gravity effect is detected from the study of the maxima of the light curves and a lower limit at 95% Confidence Level on the Quantum Gravity scale parameter of 2.9x10^14 GeV is set.Different - in many ways - from the MAGIC pre-print, so a null result is not necessarily inconsistent ...

Ken G
2007-Sep-11, 03:43 AM
Furthermore, their "lower limit" for the quantum gravity scale is at least 4 orders of magnitude below the expected Planck scale, so on the surface that would seem to render their null result pretty irrelevant. I'm not sure how the MAGIC observation manages to probe to such a more precise level.

Sock puppet
2007-Sep-11, 08:09 AM
Furthermore, their "lower limit" for the quantum gravity scale is at least 4 orders of magnitude below the expected Planck scale, so on the surface that would seem to render their null result pretty irrelevant. I'm not sure how the MAGIC observation manages to probe to such a more precise level.

MAGIC looks at far higher energies than HETE does. When the effect is energy dependent, that translates to higher sensitivity.
Oh, and an experiment that says "we looked at this, and we saw nothing unexpected" is still a good thing. It would be very unwise not to look because we expect to see nothing.

Michael Noonan
2007-Sep-11, 10:57 AM
I was working on space being curved so is it possible that two different wavelengths might arrive at slightly different times?

I was thinking more along the line of sound actually say travelling in a large curved medium like the ocean. If the path taken could be shown to be ever so slightly different based on pitch then would that help?

Michael Noonan
2007-Sep-11, 12:18 PM
I was just thinking of wave propagation so if the curvature of the ocean around the earth is too invariant then a crescent of metal such as niobium which has the best resonance of any metal to detect the path of a moving wave through a known curved medium.

This may indicate if there is a curvature associated with being in a galactic structure as such given that the spiral arms are not straight.

Given that time and space are curved and light propagates as a wave function as does sound I wondered if this helped?

Ken G
2007-Sep-11, 04:10 PM
MAGIC looks at far higher energies than HETE does. When the effect is energy dependent, that translates to higher sensitivity. OK, that makes sense.

Oh, and an experiment that says "we looked at this, and we saw nothing unexpected" is still a good thing. It would be very unwise not to look because we expect to see nothing.I agree, but the issue is not "was the experiment worth doing", it's "does it have anything to say about the interpretation of the MAGIC experiment". Owing to the shortfall in predictive power in regard to the Planck scale, I would say it does not. Indeed, it sounds like a positive result by HETE would actually be a refutation of the MAGIC interpretation as a quantum gravity effect-- on the grounds of it not seing enough of an effect.

Fortunate
2007-Sep-11, 06:08 PM
I think that GLAST will look for similar results from GRBs.

http://www.astronomytoday.com/cosmology/quantumgrav.html

GLAST will look at energies lower than those MAGIC looked at (but higher than those seen by HETE-2), but I think that the GRBs would be much further away than MAGIC's gamma-ray flairs.

Ken G
2007-Sep-12, 07:48 PM
That will be interesting to watch for. They're certainly looking for more ways to sell GLAST!

antoniseb
2007-Sep-12, 09:03 PM
If GLAST can see up to 300 GeV, AND the observations from MAGIC and Markarian 501 were correct, then at the highest energies, GLAST should see a 10-30 second delay (at 450 million light years).

IF the short burst GRBs give off gammas at that energy (not an easy assumption) this effect should be pretty obvious, and clearly defined.

Ken G
2007-Sep-12, 10:53 PM
That would be very exciting indeed-- they could sell it as "the first careful look at nothingness".

upriver
2007-Oct-04, 04:02 AM
"The MAGIC (Major Atmospheric Gamma-ray Imaging Cherenkov) telescope found that high-energy photons of gamma radiation from a distant galaxy arrived at Earth four minutes after lower-energy photons, although they were apparently emitted at the same time. If correct, that would contradict Einstein's theory of relativity, which says that all photons (particles of light) must move at the speed of light.

"Everybody's very excited," about this result, said Daniel Ferenc, a physics professor at UC Davis and a member of the MAGIC collaboration. Ferenc cautioned that the results need to be repeated with other gamma-ray sources and that a simpler explanation had not been ruled out. But, "it shows that such measurements are possible," he said.

The researchers propose that the delay could be caused by photons interacting with "quantum foam," a type of structure of space itself. Quantum foam is predicted by quantum gravity theory, an attempt to unite quantum physics and relativity at cosmic scales. "
http://www.physorg.com/news110480559.html


What else could you use besides "quantum Foam"?

New physics.....???? I thought that was the realm of ATM......

If I could provide an explanation that required "no new physics"(for real), would that be more acceptable??

The Bad Astronomer
2007-Oct-04, 04:14 AM
Yeah, we talked about this idea for GLAST at some meetings. I think it's still farfetched, but in a short GRB this may be an obvious effect. Good call.

01101001
2007-Oct-04, 04:31 AM
"If I could provide an explanation that required "no new physics"(for real), would that be more acceptable??

If you could hypothetically provide an answer, I'd rather you provided the correct answer than the one more acceptable.

Or, are you running for political office?

===

Just noticed, by its revival from older times, that there was another Q&A thread on this news: Breakdown of relativity? (also MAGIC delayed photon) (http://www.bautforum.com/questions-answers/63917-breakdown-relativity-also-magic-delayed-photon.html). Though the questions bespeak of different attitudes, most everyone interested in one will be interested in the other. (Edit: and now they are one, as described below.)

Nereid
2007-Oct-04, 06:03 AM
Another Q&A thread merged (title was "Gamma Ray Delay May Be Sign of 'New Physics'") with this one.

RGClark
2007-Oct-04, 11:33 AM
Yeah, we talked about this idea for GLAST at some meetings. I think it's still farfetched, but in a short GRB this may be an obvious effect. Good call.

According to theoretical approaches to tachyons, they should *slow down*, but still remain faster than light, as they *gain* energy:

Tachyons.
http://en.wikipedia.org/wiki/Tachyon#Basic_properties

Then the observations would have more weight if it is found that even higher energy gamma rays travel slower.


Bob Clark

Jerry
2007-Oct-05, 02:43 PM
Events energetic enough to create these gamma rays are consuming an awful lot of mass; and in doing so, completely collapse the gravity field associated with the mass converted to energy. That takes time - in the case of our own sun, (if it decided to eat itself), it is reasonable to estimate that the gravity wave peak would occur ~4 minutes after the mass-conversion peak. This is the logic tree that always gets me in trouble, but there you have it: The gamma peak may be closely related to the gravity wave peak.

Fortunate
2007-Oct-05, 06:00 PM
...it is reasonable to estimate that the gravity wave peak would occur ~4 minutes after the mass-conversion peak. This is the logic tree that always gets me in trouble, but there you have it: The gamma peak may be closely related to the gravity wave peak.

Hopefully, we can observe more such events to see how the time lag changes (or not) with distance. This has already been suggested by several others.

Thanatos
2007-Oct-07, 08:56 AM
This very interesting result bears watching. I'm not quite ready to throw GR under the bus, but am looking forward to additional studies.

upriver
2007-Oct-08, 01:58 AM
Ok. The solution to the low energy em first problem.
Nobody has said "Gee I wonder if their model is wrong!!!" Instead its all about new physics..
If an ATM guy had said any of those thing he(or she) would get laughed at with "Wheres your equations".

I have posted this paper before. The author, Petrukhin, A. A. is well published in cosmic ray circles...

Title: Cosmic ray spectrum above 1015 eV (a new approach)
Authors: Petrukhin, A. A.

"A new approach to cosmic ray description based on the model of particle generation and acceleration in plasma pinches and on supposition that a new state of matter appears in cosmic ray interactions above 1015 eV is considered. Consequences for various aspects of cosmic ray physics and some possibilities to check this hypothesis are discussed."

http://adsabs.harvard.edu/abs/2005ICRC....3..137P

A plasma pinch has the required slow rise and slow fall time.

No new physics (even though it is discussed in the preceding paper), quantum foam, dark matter or smashing neutron stars. Relativity is safe even though I think it has problems, and EM/light has a speed limit.
Just like the flux tubes the we see locally, that is where a pinch(reconnection) takes place as Cluster has observed. They just happened to catch the first part. And on a larger scale, like in the DNA nebula......
These signals are characteristic of a compression event. Just like a pulsar is.

Thats it. All you have to do is scale up an existing phenomena.......

upriver
2007-Oct-10, 03:53 AM
This is direct detection of a plasma pinch accelerating particles. Are you with me on this one. They even say it. They just dont know what to call it....
Can ya feel the glory??? Validation 101...

NASA: major step toward knowing origin of cosmic rays.
"Suzaku spectra of RXJ1713.7 provide independent evidence of rapid acceleration. They show that the hot spots have tangled magnetic fields, which allow particles to bounce back and forth rapidly until they are accelerated to very high energies. Since electrons and protons of a given energy are accelerated at the same high rate, but protons don’t radiate away their energy as electrons do, Uchiyama’s team argues that protons will be accelerated to the higher energies needed to match the energies seen in cosmic rays striking Earth’s atmosphere."
http://www.physorg.com/news111166810.html

mugaliens
2007-Oct-11, 06:17 PM
Yeah, that doesn't sound like it has anything at all to do with quantum gravity, the energies are nowhere close to Planck scales. It instead sounds like a challenge to basic relativity, the only one I've heard of in a long time-- but my money is still on error in observational interpretation.

The rate at which light escapes gravitational wells is based upon it's wavelength. Can't recall which, but if I'm not mistaken, it's the lower energies which lag the higher ones.

antoniseb
2007-Oct-11, 06:24 PM
The rate at which light escapes gravitational wells is based upon it's wavelength. Can't recall which, but if I'm not mistaken, it's the lower energies which lag the higher ones.
Generally, photons travel at 'c' or so close to it you can't measure the difference, but the gravity well doesn't change the rate of speed. It only affects the wavelength.

Now, in the case we are discussing here, with photons with energies greater than 1 TeV, it is the high energy photons that go a wee bit slower, but not because of a gravity well.

Nereid
2007-Oct-15, 12:17 AM
This is direct detection of a plasma pinch accelerating particles. Are you with me on this one. They even say it. They just dont know what to call it....
Can ya feel the glory??? Validation 101...

NASA: major step toward knowing origin of cosmic rays.
"Suzaku spectra of RXJ1713.7 provide independent evidence of rapid acceleration. They show that the hot spots have tangled magnetic fields, which allow particles to bounce back and forth rapidly until they are accelerated to very high energies. Since electrons and protons of a given energy are accelerated at the same high rate, but protons don’t radiate away their energy as electrons do, Uchiyama’s team argues that protons will be accelerated to the higher energies needed to match the energies seen in cosmic rays striking Earth’s atmosphere."
http://www.physorg.com/news111166810.htmlupriver, first, I'm not sure what this Suzaku-based finding has to do with the topic of this thread; would be so kind as to elaborate please?

Second, that UHE cosmic rays may be produced in supernova remnants is very old news. For many decades now researchers have been digging deeper and deeper - which mechanisms? in what combinations? what quantitative models match best? how can new observations best constrain these most favoured models? where else should we look for corroboration?

But maybe I'm misunderstanding some key part of your post? Would you be so kind as to elaborate? What do you think this paper validates (that previously lacked validation)?

upriver
2007-Oct-24, 10:57 PM
upriver, first, I'm not sure what this Suzaku-based finding has to do with the topic of this thread; would be so kind as to elaborate please?

Second, that UHE cosmic rays may be produced in supernova remnants is very old news. For many decades now researchers have been digging deeper and deeper - which mechanisms? in what combinations? what quantitative models match best? how can new observations best constrain these most favoured models? where else should we look for corroboration?

But maybe I'm misunderstanding some key part of your post? Would you be so kind as to elaborate? What do you think this paper validates (that previously lacked validation)?


Shoot, I thought I was going to get away with this one.

They finally have enough information to formulate a good description.
That description has converged onto a description of a plasma pinch, just with astronomer language instead of already established plasma physicist language.

Again, here is the hypothesis.

Title: Cosmic ray spectrum above 1015 eV (a new approach)
Authors: Petrukhin, A. A.

"A new approach to cosmic ray description based on the model of particle generation and acceleration in plasma pinches and on supposition that a new state of matter appears in cosmic ray interactions above 1015 eV is considered. Consequences for various aspects of cosmic ray physics and some possibilities to check this hypothesis are discussed."
http://adsabs.harvard.edu/abs/2005ICRC....3..137P


Notice that they talk about a "new state of matter". That is not required for the "generation of cosmic rays in plasma pinches" part to work. But that part is very interesting because it would explain some of the results that Sandia Z-machine is getting, and that we are seeing.
Let me post a picture from the lab. This image is of a expanding sonoluminescence bubble.
This bubble is about 2mm in dia. The pressure in the reactor is 1000psi. These shock waves(the black and white striations) my be the strongest ever created by man. This is on a delayed flash triggered by the actual sono flash. We are not sure what is going on inside the bubble.:-)
http://www.brantcallahan.com/images/shock%20dt45ns%2015ns%20flash%201000psi%204.jpg
Here is a test reactor after I just set it up.
http://www.brantcallahan.com/images/SBSLoptical%20table.jpg

But I digress. So this SL process is much like plasma pinch is way because we are compressing a fuel mixture in a bubble to fusion temperatures. And we are trying to achieve a certain convergence ratio over a certain time.
Hence my interest in plasma pinches.



Second, that UHE cosmic rays may be produced in supernova remnants is very old news. For many decades now researchers have been digging deeper and deeper - which mechanisms? in what combinations? what quantitative models match best? how can new observations best constrain these most favoured models? where else should we look for corroboration?


There is the one model, above, that they have either not seen or ignored.

"They show that the hot spots have tangled magnetic fields, which allow particles to bounce back and forth rapidly until they are accelerated to very high energies."

When they show that is not a description of a pinch, I will eat my words.
Also I suspect that cosmic rays are generated as close as the "reconnections" that happen locally.
They will use frozen in magnetic fields. Which are baloney the way they are being used.
These hotspots have x-ray variability of about a year.
That I believe, is also a longer time(/.5) period than a shock wave passing that has enough energy to "heat" the "gas" to x-ray temperatures.



But maybe I'm misunderstanding some key part of your post? Would you be so kind as to elaborate? What do you think this paper validates (that previously lacked validation)?

That plasma pinches are a valid phenomena in space generating high energy particles on a large scale as well as a small scale. Even to the point of generating new electrons and protons(maybe neutron decay), and as a mechanism for nucleosynthesis.
This is the only model,(from my limited understanding) that exactly matches the parameters of cosmic ray energy distribution.

Now that there is some establishment(at least in word salad) of what I mean, we could conceivably use this mechanism to explain GRB's and other high energy outbursts. Especially ones that defy the laws of physics.
When you use this other tool, you find that no laws of physics are broken, the only thing you have to do is postulate some sort of charge separation or potential difference between 2 points on a large scale. Like between the galactic center and the rim. The gc is observed to put out massive quantities of protons and electrons.
Milky Way Black Hole May Be a Colossal 'Particle Accelerator'
"This graphic illustrates the idea that the black hole at the center of the Milky Way is like an extremely powerful particle accelerator, revving up protons in the surrounding magnetic plasma and slinging them into lower-energy protons with such energy that high-energy gamma rays result from the collision."
http://www.physorg.com/news91731386.html
(Another pinch description.)

If there is a difference in potential. Then you could have a current flow in a unbalanced plasma(unbalance of electron and proton energies, or species). Even a neutral plasma is a conductor like a wire.
Its not that hard of a leap to make.

I think this(a plasma pinch) is a good answer for the differential in arrival times of different wavelengths, because it preserves current basic physics, and is a real phenomena.

ToSeek
2007-Oct-25, 01:50 PM
Post by clancysmith removed for ATM content in a non-ATM area.

Nereid
2007-Oct-27, 01:21 PM
upriver, first, I'm not sure what this Suzaku-based finding has to do with the topic of this thread; would be so kind as to elaborate please?

Second, that UHE cosmic rays may be produced in supernova remnants is very old news. For many decades now researchers have been digging deeper and deeper - which mechanisms? in what combinations? what quantitative models match best? how can new observations best constrain these most favoured models? where else should we look for corroboration?

But maybe I'm misunderstanding some key part of your post? Would you be so kind as to elaborate? What do you think this paper validates (that previously lacked validation)?Shoot, I thought I was going to get away with this one.

They finally have enough information to formulate a good description.
That description has converged onto a description of a plasma pinch, just with astronomer language instead of already established plasma physicist language.

Again, here is the hypothesis.

Title: Cosmic ray spectrum above 1015 eV (a new approach)
Authors: Petrukhin, A. A.

"A new approach to cosmic ray description based on the model of particle generation and acceleration in plasma pinches and on supposition that a new state of matter appears in cosmic ray interactions above 1015 eV is considered. Consequences for various aspects of cosmic ray physics and some possibilities to check this hypothesis are discussed."
http://adsabs.harvard.edu/abs/2005ICRC....3..137P


Notice that they talk about a "new state of matter". That is not required for the "generation of cosmic rays in plasma pinches" part to work. But that part is very interesting because it would explain some of the results that Sandia Z-machine is getting, and that we are seeing.
Let me post a picture from the lab. This image is of a expanding sonoluminescence bubble.
This bubble is about 2mm in dia. The pressure in the reactor is 1000psi. These shock waves(the black and white striations) my be the strongest ever created by man. This is on a delayed flash triggered by the actual sono flash. We are not sure what is going on inside the bubble.:-)
http://www.brantcallahan.com/images/shock%20dt45ns%2015ns%20flash%201000psi%204.jpg
Here is a test reactor after I just set it up.
http://www.brantcallahan.com/images/SBSLoptical%20table.jpg

But I digress. So this SL process is much like plasma pinch is way because we are compressing a fuel mixture in a bubble to fusion temperatures. And we are trying to achieve a certain convergence ratio over a certain time.
Hence my interest in plasma pinches.

Second, that UHE cosmic rays may be produced in supernova remnants is very old news. For many decades now researchers have been digging deeper and deeper - which mechanisms? in what combinations? what quantitative models match best? how can new observations best constrain these most favoured models? where else should we look for corroboration?
There is the one model, above, that they have either not seen or ignored.

"They show that the hot spots have tangled magnetic fields, which allow particles to bounce back and forth rapidly until they are accelerated to very high energies."

When they show that is not a description of a pinch, I will eat my words.
Also I suspect that cosmic rays are generated as close as the "reconnections" that happen locally.
They will use frozen in magnetic fields. Which are baloney the way they are being used.
These hotspots have x-ray variability of about a year.
That I believe, is also a longer time(/.5) period than a shock wave passing that has enough energy to "heat" the "gas" to x-ray temperatures.

But maybe I'm misunderstanding some key part of your post? Would you be so kind as to elaborate? What do you think this paper validates (that previously lacked validation)?
That plasma pinches are a valid phenomena in space generating high energy particles on a large scale as well as a small scale. Even to the point of generating new electrons and protons(maybe neutron decay), and as a mechanism for nucleosynthesis.
This is the only model,(from my limited understanding) that exactly matches the parameters of cosmic ray energy distribution.

Now that there is some establishment(at least in word salad) of what I mean, we could conceivably use this mechanism to explain GRB's and other high energy outbursts. Especially ones that defy the laws of physics.
When you use this other tool, you find that no laws of physics are broken, the only thing you have to do is postulate some sort of charge separation or potential difference between 2 points on a large scale. Like between the galactic center and the rim. The gc is observed to put out massive quantities of protons and electrons.
Milky Way Black Hole May Be a Colossal 'Particle Accelerator'
"This graphic illustrates the idea that the black hole at the center of the Milky Way is like an extremely powerful particle accelerator, revving up protons in the surrounding magnetic plasma and slinging them into lower-energy protons with such energy that high-energy gamma rays result from the collision."
http://www.physorg.com/news91731386.html
(Another pinch description.)

If there is a difference in potential. Then you could have a current flow in a unbalanced plasma(unbalance of electron and proton energies, or species). Even a neutral plasma is a conductor like a wire.
Its not that hard of a leap to make.

I think this(a plasma pinch) is a good answer for the differential in arrival times of different wavelengths, because it preserves current basic physics, and is a real phenomena.
I'm still puzzled how the RXJ1713.7-3946 observations, and the Uchiyama et al. paper* relate to the MAGIC observations - is it your idea that plasma pinches are somehow involved in each?

It's worth quoting the abstract of the Uchiyama et al. paper:
Galactic cosmic rays (CRs) are widely believed to be accelerated by shock waves associated with the expansion of supernova ejecta into the interstellar medium. A key issue in this long-standing conjecture is a theoretical prediction that the interstellar magnetic field can be substantially amplified at the shock of a young supernova remnant (SNR) through magnetohydrodynamic waves generated by cosmic rays. Here we report a discovery of the brightening and decay of X-ray hot spots in the shell of the SNR RXJ1713.7-3946 on a one-year timescale. This rapid variability shows that the X-rays are produced by ultrarelativistic electrons through a synchrotron process and that electron acceleration does indeed take place in a strongly magnetized environment, indicating amplification of the magnetic field by a factor of more than 100. The X-ray variability also implies that we have witnessed the ongoing shock-acceleration of electrons in real time. Independently, broadband X-ray spectrometric measurements of RXJ1713.7-3946 indicate that electron acceleration proceeds in the most effective (`Bohm-diffusion') regime. Taken together, these two results provide a strong argument for acceleration of protons and nuclei to energies of 1PeV (1015eV) and beyond in young supernova remnants.Note the phrase 'long-standing conjecture'; the 24 references in the paper (http://adsabs.harvard.edu/cgi-bin/nph-ref_query?bibcode=2007Natur.449..576U&amp;refs=REFEREN CES&amp;db_key=AST) include one dated 1983 and two 1987; no reference to the Petrukhin conference presentation.

It would seem that Blandford and Eichler's 1987 paper (Particle Acceleration at Astrophysical Shocks - a Theory of Cosmic-Ray Origin (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TVP-46T3DRC-20&_user=10&_coverDate=10%2F31%2F1987&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=f1f1d8ec634956447b642eb2f18ee999)) is one of the most widely cited, in terms of presenting how 'tangled magnetic fields' can produce high energy particles. In any case, it's worth presenting the abstract of this 1987 paper here:
The theory of first order Fermi acceleration at collisionless astrophysical shock fronts is reviewed. Observations suggest that shock waves in different astrophysical environments accelerate cosmic rays efficiently. In the first order process, high energy particles diffuse through Alfvén waves that scatter them and couple them to the background plasma. These particles gain energy, on the average, every time they cross the schock front and bounce off approaching scattering centers. Calculations demonstrate that the distribution function transmitted by a plane shock is roughly a power law in momentum with slope similar to that inferred in galactic cosmic ray sources. The generation of the scattering Alfvén waves by the streaming cosmic rays is described and it is argued that the wave amplitude is probably non-linear within sufficiently strong astrophysical shocks. Hydromagnetic scattering can operate on the thermal particles as well, possibly establishing the shock structure. This suggests a model of strong collisionless shocks in which high energy particles are inevitably produced very efficiently. Observable consequences of this model, together with its limitations and some alternatives, are described. Cosmic ray origin and astrophysical shocks can no longer be considered separately.Perhaps there is a misalignment wrt terms ('plasma pinch' vs 'first order Fermi acceleration at collisionless astrophysical shock fronts'), but perhaps not. AFAIK, there has been at least one paper (http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1992ITPS...20..898T&db_key=AST&data_type=HTML&format=&high=42ca922c9c06116) on plasma pinches as possible sources of cosmic rays, but it did not refer to supernova remnants, and, curiously, did not cite Blandford and Eichler's 1987 paper (so perhaps Trubnikov already accepted that, pace upriver, the two are very different?).

*Extremely fast acceleration of cosmic rays in a supernova remnant (http://adsabs.harvard.edu/abs/2007Natur.449..576U)

upriver
2007-Oct-28, 05:27 AM
I'm still puzzled how the RXJ1713.7-3946 observations, and the Uchiyama et al. paper* relate to the MAGIC observations - is it your idea that plasma pinches are somehow involved in each?

It's worth quoting the abstract of the Uchiyama et al. paper:


Quote:
Galactic cosmic rays (CRs) are widely believed to be accelerated by shock waves associated with the expansion of supernova ejecta into the interstellar medium. A key issue in this long-standing conjecture is a theoretical prediction that the interstellar magnetic field can be substantially amplified at the shock of a young supernova remnant (SNR) through magnetohydrodynamic waves generated by cosmic rays. Here we report a discovery of the brightening and decay of X-ray hot spots in the shell of the SNR RXJ1713.7-3946 on a one-year timescale. This rapid variability shows that the X-rays are produced by ultrarelativistic electrons through a synchrotron process and that electron acceleration does indeed take place in a strongly magnetized environment, indicating amplification of the magnetic field by a factor of more than 100. The X-ray variability also implies that we have witnessed the ongoing shock-acceleration of electrons in real time. Independently, broadband X-ray spectrometric measurements of RXJ1713.7-3946 indicate that electron acceleration proceeds in the most effective (`Bohm-diffusion') regime. Taken together, these two results provide a strong argument for acceleration of protons and nuclei to energies of 1PeV (1015eV) and beyond in young supernova remnants.

Note the phrase 'long-standing conjecture'; the 24 references in the paper include one dated 1983 and two 1987; no reference to the Petrukhin conference presentation.

It would seem that Blandford and Eichler's 1987 paper (Particle Acceleration at Astrophysical Shocks - a Theory of Cosmic-Ray Origin) is one of the most widely cited, in terms of presenting how 'tangled magnetic fields' can produce high energy particles. In any case, it's worth presenting the abstract of this 1987 paper here:


Quote:
The theory of first order Fermi acceleration at collisionless astrophysical shock fronts is reviewed. Observations suggest that shock waves in different astrophysical environments accelerate cosmic rays efficiently. In the first order process, high energy particles diffuse through Alfvén waves that scatter them and couple them to the background plasma. These particles gain energy, on the average, every time they cross the schock front and bounce off approaching scattering centers. Calculations demonstrate that the distribution function transmitted by a plane shock is roughly a power law in momentum with slope similar to that inferred in galactic cosmic ray sources. The generation of the scattering Alfvén waves by the streaming cosmic rays is described and it is argued that the wave amplitude is probably non-linear within sufficiently strong astrophysical shocks. Hydromagnetic scattering can operate on the thermal particles as well, possibly establishing the shock structure. This suggests a model of strong collisionless shocks in which high energy particles are inevitably produced very efficiently. Observable consequences of this model, together with its limitations and some alternatives, are described. Cosmic ray origin and astrophysical shocks can no longer be considered separately.

Perhaps there is a misalignment wrt terms ('plasma pinch' vs 'first order Fermi acceleration at collisionless astrophysical shock fronts'), but perhaps not. AFAIK, there has been at least one paper on plasma pinches as possible sources of cosmic rays, but it did not refer to supernova remnants, and, curiously, did not cite Blandford and Eichler's 1987 paper (so perhaps Trubnikov already accepted that, pace upriver, the two are very different?).

*Extremely fast acceleration of cosmic rays in a supernova remnant

*Extremely fast acceleration of cosmic rays in a supernova remnant (http://adsabs.harvard.edu/abs/2007Natur.449..576U)

I wish I had access to the Trubnikov paper for comparison. The point I'm trying to make is that its all the same, SNR or not.

All of these observations describe plasma pinch activity. And it doesnt matter where you are, this works over a broad range of scales. It is also known as reconnection.



Cluster opens a new window on ‘magnetic reconnection’ in the near-Earth space.
Magnetic reconnection is a process that can occur almost anywhere that a magnetic field is found. In a reconnection event, the magnetic field lines are squeezed together somehow and spontaneously reconfigure themselves. This releases energy. When it occurs near the surface of the Sun, such an event powers giant solar flares that can release thousands of millions of tonnes of electrically charged particles into space.
http://www.esa.int/esaCP/SEMZN9Q11ZE_index_0.html

Largest Magnetic Reconnection Region Ever Observed
http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=38577

The term reconnection is a misnomer, and as I have described elsewhere, it is a pinch between 2 filaments in a twisted flux tube.

Only a plasma pinch has the characteristics necessary to generate particles of the energies we are talking about. And it is better than a "rough match". It has the necessary characteristics to produce a delay in emitted energies(saving physics).

I just want to focus on this part here from the abstract of the Uchiyama et al. paper:



Galactic cosmic rays (CRs) are widely believed to be accelerated by shock waves associated with the expansion of supernova ejecta into the interstellar medium.


So the physical shock waves propagating through plasma. The idea that there is still acceleration going on for some time after the shock has passed bothers me.



A key issue in this long-standing conjecture is a theoretical prediction that the interstellar magnetic field can be substantially amplified at the shock of a young supernova remnant (SNR) through magnetohydrodynamic waves generated by cosmic rays.


The interstellar magnetic field can be amplified(locally with no action from the galactic center!!!???).
At the shock of the SNR by MHD waves generated by cosmic rays.
So what they are saying is that the magnetic field strength is a byproduct of cosmic ray generation.

That it is all mechanically(shock wave) driven instead of electrically(electron intensity) driven.

We both know that magnetic field strength changes because the intensity of the electrons feeding it vary. That is basic physics.

Do you see the error in what they are saying?

Here is their story.
The shock bone is connected to the cosmic ray bone.
The cosmic ray bone is connected to the MHD wave bone.
The MHD wave bone is connected to the magnetic bone.

My version:
The electron flow bone is connected to the magnetic bone.
The magnetic bone is connected to the cosmic ray bone.

See the difference?



Here we report a discovery of the brightening and decay of X-ray hot spots in the shell of the SNR RXJ1713.7-3946 on a one-year timescale. This rapid variability shows that the X-rays are produced by ultrarelativistic electrons through a synchrotron process and that electron acceleration does indeed take place in a strongly magnetized environment, indicating amplification of the magnetic field by a factor of more than 100.


Yes, yes, yes, so close. "Indicating amplification" only because the have no way to provide a primary independent source of magnetism(electron flow) or understand about how a pinch works. Again, localized tangled magnetic field comes to mind.
The only way to amplify a magnetic field is increase the electron energy or population.
Electron(proton) acceleration takes place in a pinched flux tube just like suggested by Petrukhin. Easy, breezy, beautiful.
Considering all the places we have seen flux tubes, I would say that a SNR is a good candidate.

Or even the center of our galaxy.
DNA Nebula.
http://www.anthonares.net/2006/03/184.html

Middle top is a huge "flux tube".
Supernova Remnant N 63A.
http://sci.esa.int/science-e-media/img/4e/heic0507a.jpe

So again I'm saying that a plasma pinch works for all these problems. There are different form of pinches, but the basic idea is that you have some electron flow through a flux tube. Then there is a variation in this flow that causes a change in the Biot-Savart forces between the tubes, or an increase in flow which causes a constriction in the flux tube(s), effectively squeezing the plasma, causing an acceleration in particle energies.

Nereid
2007-Oct-28, 02:42 PM
I've started a new Q&A thread, What are the (detailed) mechanisms for cosmic ray production, in SNR? (http://www.bautforum.com/questions-answers/66358-what-detailed-mechanisms-cosmic-ray-production-snr.html), to address your key question.

Let's continue in that thread, and leave this one to the MAGIC GRB observations and interpretations.