Milky Way's super-efficient particle accelerators caught in the act

Jun 25, 2009
Image of part of a stellar remnant whose explosion was recorded in 185 A.D. By studying this remnant in detail, a team of astronomers was able to solve the mystery of the Milky Way’s super-efficient particle accelerators. The team shows that the shock wave visible in this area is very efficient at accelerating particles and the energy used in this process matches the number of cosmic rays observed on Earth. North is toward the top right and east to the top left. The image is about six arc minutes across. Credit: ESO/E. Helder & NASA/Chandra

Thanks to a unique "ballistic study" that combines data from ESO's Very Large Telescope and NASA's Chandra X-ray Observatory, astronomers have now solved a long-standing mystery of the Milky Way's particle accelerators. They show in a paper published today on Science Express that cosmic rays from our galaxy are very efficiently accelerated in the remnants of exploded stars.

During the Apollo flights astronauts reported seeing odd flashes of light, visible even with their eyes closed. We have since learnt that the cause was — extremely from outside the Solar System arriving at the Earth, and constantly bombarding its atmosphere. Once they reach Earth, they still have sufficient energy to cause glitches in electronic components.

Galactic cosmic rays come from sources inside our home galaxy, the , and consist mostly of protons moving at close to the speed of light, the "ultimate speed limit" in the Universe. These protons have been accelerated to energies exceeding by far the energies that even CERN's will be able to achieve.

"It has long been thought that the super-accelerators that produce these cosmic rays in the Milky Way are the expanding envelopes created by exploded stars, but our observations reveal the smoking gun that proves it", says Eveline Helder from the Astronomical Institute Utrecht of Utrecht University in the Netherlands, the first author of the new study.

"You could even say that we have now confirmed the calibre of the gun used to accelerate cosmic rays to their tremendous energies", adds collaborator Jacco Vink, also from the Astronomical Institute Utrecht.

For the first time Helder, Vink and colleagues have come up with a measurement that solves the long-standing astronomical quandary of whether or not stellar explosions produce enough accelerated particles to explain the number of cosmic rays that hit the Earth's atmosphere. The team's study indicates that they indeed do and directly tells us how much energy is removed from the shocked gas in the stellar explosion and used to accelerate particles.

"When a star explodes in what we call a supernova a large part of the explosion energy is used for accelerating some particles up to extremely high energies", says Helder. "The energy that is used for particle acceleration is at the expense of heating the gas, which is therefore much colder than theory predicts".

The researchers looked at the remnant of a star that exploded in AD 185, as recorded by Chinese astronomers. The remnant, called RCW 86, is located about 8200 light-years away towards the constellation of Circinus (the Drawing Compass). It is probably the oldest record of the explosion of a star.

Using ESO's Very Large Telescope, the team measured the temperature of the gas right behind the shock wave created by the . They measured the speed of the shock wave as well, using images taken with NASA's X-ray Observatory Chandra three years apart. They found it to be moving at between 10 and 30 million km/h, between 1 and 3 percent the speed of light.

The temperature of the gas turned out to be 30 million degrees Celsius. This is quite hot compared to everyday standards, but much lower than expected, given the measured shock wave's velocity. This should have heated the gas up to at least half a billion degrees.

"The missing energy is what drives the ", concludes Vink.

More information: This research was presented in a paper to appear in Science: Measuring the cosmic ray acceleration efficiency of a supernova remnant, by E. A. Helder et al.

Source: ESO (news : web)

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omatumr
1.5 / 5 (8) Jun 25, 2009
PROTONS ACCELERATED IN SUPERNOVA REMNANTS?

Supernovae are indeed violent, but what could be accelerating protons to "close to the speed of light" in the SN remnant? The magnetic field of the neutron star?

With kind regards,
Oliver K. Manuel
http://www.omatumr.com
daywalk3r
3.5 / 5 (15) Jun 25, 2009
PROTONS ACCELERATED IN SUPERNOVA REMNANTS?
Supernovae are indeed violent, but what could be accelerating protons to "close to the speed of light" in the SN remnant?

I think it's just unfortunate wording used by the writer of this article that causes some confusion here. As I understood it, what they meant is that the shockwave (as "the remnant") is causing the proton acceleration when it hits the surrounding gas as it propagates. And that it is most probably the reason why the gas is "only" 30M degrees hot after the collision and not the expected 500M, because a part of the energy is used up on that proton acceleration.
RAL
3.3 / 5 (3) Jun 25, 2009
Very interesting article. But it seems to me what they have identified is missing energy vs expectations, not the cause or pathway that said energy took. They are making an assumption that this energy went into particle acceleration. I'm not criticizing, just seeking clarification. And I echo the question of OKM above regarding the exact mechanism.

If someone has an article addressing the mechanism of the acceleration, please post a link.
daywalk3r
3.2 / 5 (13) Jun 25, 2009
And I echo the question of OKM above regarding the exact mechanism.

They are proposing that (quote) "the super-accelerators that produce these cosmic rays in the Milky Way are the expanding envelopes created by exploded stars" - which should mean that the mechanism that is responsible for the proton acceleration involves the shockwave hitting the (relatively) static gas. The fast propagating shockwave hits the gas at a speed around 3%c, which causes the gas to get highly compressed and heated within a short timeframe of the impact, exciting it and so causing the "emission" of highly energized protons(?). My guess is that there could also be a quite high charge difference between the gas and the shockwave particles and that this could play some role in the whole process. Though I might be completely wrong on everything.. After all I'm just trying to guess here - eg. being "constructive" ;o)
mattytheory
1.8 / 5 (5) Jun 26, 2009
^So are the authors. =P

Unfortunately, that is what all of science is though... our best explanation for things is merely our best "guess" based on the evidence, or, at least our most educated one.
omatumr
2 / 5 (8) Jun 26, 2009
YES, SCIENCE IS THE BEST GUESS BASED ON EVIDENCE

The above expresses my conclusion too, based on 50 years of research. E.g., a guess made 34 years ago, when forced to do so by unexpected experimental data:

In 1975 the data showed that all of the primordial Helium-4 in meteorites is closely associated with strange xenon containing excess Xe-136 from rapid neutron capture in a supernova. There is no primordial Helium-4 associated with the normal xenon (Earth-like) in meteorites.

http://tinyurl.com/2cmusk

Dr. D. D. Sabu and I "guessed" that the r-process that made "strange xenon" occurred in the outer Helium-rich region of the supernova that gave birth to the solar system and that "normal xenon" (Earth-like) came from the iron-rich interior of the supernova where fusion reactions had consumed all of the Helium and other lightweight, low-Z elements.

Many other guesses were negated by later research findings. The above guess has survived for 34 years.

With kind regards,
Oliver K. Manuel
http://www.omatumr.com/
JukriS
1 / 5 (6) Jun 26, 2009
Einstein already told, what a massive/density planet, time is going to be more slow!

Why Einstein never give that idea for physics of particle?

What a massive/density particle, time is going to be more slow and thats why particle dont emit so fast energy.

When neutrinos come out from sun, they are hot/density. The new neutrinos time is slow. First neutrinos emit energy%uFEFF slow. Later neutrinos emit energy faster. When neutrinos are here, near earth, they give some kineticenergy for our nucleus of atoms. When neutrinos are inside gasplanets, they emit more energy (kineticenergy) for gasplanets nucleus of atoms. This is relativity of real!

Sun exploding and pushing exploding planets far away from exploding Sun!

Space dont expanding or curving. Nucleus of atoms are expanding/exploding and emit energywaves who have a nature of electrons and particle, who also expanding and emit energy. Electrons just move to next exploding nucleus of atoms and get this exploding faster etc. Before that electrons just give some change of pressure for energywaves who pushing themselfs out from exploding nucleus of atoms!

THIS IDEA IS REVOLUTION OF SCIENCE!

http://www.onesim....com/296
omatumr
1 / 5 (3) Jun 26, 2009
If someone has an article addressing the mechanism of the acceleration, please post a link.


I don't know the method of acceleration being proposed here.

But there are indications that protons produced by neutron decay may be accelerated by the strong magnetic field of a.) a neutron star that remains after supernova explosion or b.) by Bose-Einstein condensation of iron-rich material into a rotating, superfluid, superconductor surrounding the neutron star. http://arxiv.org/.../0501441

With kind regards,
Oliver K. Manuel
http://www.omatumr.com/

brant
1 / 5 (1) Jun 26, 2009
The most efficient particle accelerator is an electric field. You can make a 3 GeV particle in 3 inches!!
lomed
5 / 5 (3) Jun 28, 2009
Einstein already told, what a massive/density planet, time is going to be more slow!

Why Einstein never give that idea for physics of particle?

What a massive/density particle, time is going to be more slow and thats why particle dont emit so fast energy.
Special Relativity applies to anything being described in physics. There was/is no restriction to large objects. In fact, when quantum theory was formulated taking into account special relativity (the Dirac Equation at first, and all of modern accepted quantum theory) spin quantization was discovered to be "naturally" part of the theory (i.e. it didn't have to be added in ad hoc.)

Just speculating (I haven't looked up any information about the subject recently), but if the shockwave generates temperatures of 30 million degrees (hotter than the center of the Sun) any molecules in its path will be reduced to their constituent atoms, and those atoms will be stripped of all their electrons. The electrons, being much lighter than the nuclei, will be imparted with a much higher velocity than the associated protons and neutrons of their former nuclei producing a large difference in charge between two regions (a region essentially within the shock of negative charge and a region behind it (with respect to the propagation direction of the wave) with a corresponding positive charge) leading to a large difference in electrical potential (aka a large electric field) that would produce a large acceleration. Since hydrogen is the most common element in the universe, and since its nucleus is the lightest of any element, consisting as it does of a single proton, it would make sense that this would be a method for explaining the production of high energy protons using a supernova shockwave. (Indeed, I think it would require extremely artificial circumstances for such a shockwave not to accelerate some protons in the way just described.)
toyo
not rated yet Jun 28, 2009
I quote from the article:
"The researchers looked at the remnant of a star that exploded in AD 185, as recorded by Chinese astronomers. The remnant, called RCW 86, is located about 8200 light-years away."
???
Am I the only one to see a problem here?
Let me spell it out.
How can you see something that happened a little over two thousand years ago at a location that is Eight Thousand light-years away?
Can someone please try to explain this to me?
toyo
not rated yet Jun 28, 2009
I quote from the article:

"The researchers looked at the remnant of a star that exploded in AD 185, as recorded by Chinese astronomers. The remnant, called RCW 86, is located about 8200 light-years away."

???

Am I the only one to see a problem here?

Let me spell it out.

How can you see something that happened a little over two thousand years ago at a location that is Eight Thousand light-years away?

Can someone please try to explain this to me?

Correction, I just now noticed the AD.
We are talking about light travelling at nearly 4.5 times the speed of light.
lomed
5 / 5 (1) Jun 29, 2009
I quote from the article:

"The researchers looked at the remnant of a star that exploded in AD 185, as recorded by Chinese astronomers. The remnant, called RCW 86, is located about 8200 light-years away."

???

Am I the only one to see a problem here?

Let me spell it out.

How can you see something that happened a little over two thousand years ago at a location that is Eight Thousand light-years away?

Can someone please try to explain this to me?


As the quote you cited implies, the Chinese astronomers saw the star explode in 185 AD. Assuming the star is/was 8200 light-years away, the explosion happened around 8016 BC (not 8015 since there was no year zero.)



On second (or so) look, the (first) sentence you quoted is a little unclear in its wording. One interpretation of the sentence is that the star exploded in 185 AD. However, there probably should not be a comma after "AD 185" since the adjectival phrase "as recorded by Chinese astronomers" describes "a star that exploded in AD 185", which in turn describes what kind of remnant "the remnant" was at which "The researchers looked". Thus, when the sentence is properly written and understood, one sees that it is meant that the Chinese astronomers recorded the explosion in 185 AD, the first sentence gives no clue as to when the star actually exploded.
RAL
3 / 5 (2) Jun 30, 2009
I tracked down the pdf of the original paper here:
http://arxiv.org/pdf/0906.4553 in which they elaborate on their reasoning and mathematically present the equations. My understanding of the paper, (which I freely admit is less than perfect) is that the energetics they are looking at involve actual thermal shock from the supernova material hitting the cavity wall, not linear acceleration from remnant magnetic fields.

Exciting material; kudos to PhysOrg for publishing the summary!
Quantum_Conundrum
1 / 5 (6) Jun 30, 2009
can someone PLEASE solve the Quantum Conundrum, i.e.

How is it possible that Relativity can be true at the macroscopic level, and yet at the nano-scale quantum theory holds.

Relativity requires all constants to be continuous for all space and time and for all reference frames on ther intervale from V=0 to V -> c. (i.e. "arbitrarily close to.)

Quantum theory on the other hand claims that everything must exist in discreet packets of exact whole integer values or exact rational fractional values.

Thus, it would seem contradictory that anything "continuous" could exist at a macroscopic level when the underlying quantum level is non-continuous.

How then does a proton accelerate from 0 to 0.9c?

Quantum theory requires that the velocity of a particle be equal to that given by the sum of an arbitrary number of "quanta" of momentum, but in relativity this number (i.e. the number of quanta) would be different for all unigue reference frames.

Paradoxically, any object would then be composed of a different number of particles, depending on which reference frame it is viewed from.


This implies that, in this above problem, and really in all the universe, protons are NOT particles of the same type which move at velocities from 0->c, but rather, there is an entire family of unique particles all called "protons" which appear identical in every respect except that each succssive particle contains one extra quantum unit of momentum.

Thus, if I observe two "protons", one at rest relative to me, the other moving at 0.9c, then in the quantum sense, it actually is not technically correct to say that proton 1 is the same as proton 2 except momentum, not at all.

The first proton has a positive charge and a molar mass of approximately 1g/mol. Its momentum relative to me is zero, and its velocity is zero.

The second proton also has a positive charge, but has a very different mass(due to the relativity of maass), velocity, and momentum(due to the change in both velocity and mass).

Thus, the second particle is actually a completely different particle than the first, even though it has many of the same electrical and nuclear properties. The reason is that it must contain some extra "quanta" of one type or another to explain the extra mass and the velocity.
lomed
5 / 5 (1) Jul 02, 2009
Quantum theory requires that the velocity of a particle be equal to that given by the sum of an arbitrary number of "quanta" of momentum, but in relativity this number (i.e. the number of quanta) would be different for all unigue reference frames.
While angular momentum is quantized, linear momentum is not. As far as I know, there is nothing to stop a proton from being measured to a speed equal to any of the real numbers between 0 and c (inclusive and non-inclusive, respectively.) Additionally, while some theories of quantum gravity predict space-time is quantized, Quantum Electrodynamics and Quantum Chromodynamics (the two theories that make up the currently accepted basis of quantum theory and have stood up to a large variety of tests) are built on a background of continuous space-time (the background is Special Relativity, which is generalizable to General Relativity.)