Cause of Cosmic Rays (Arnon Dar)

[Martin]

there is a new paper by Arnon Dar:

 

http://arxiv.org/astro-ph/0408310

 

"The Origin of Cosmic Rays - A 96-Year-Old Puzzle Solved?"

 

It is important to understand how GammaRay Bursts (GRB) and how Cosmic Rays (CR) are produced because more and more these days this stuff is taking the place of Particle Accelerator beams in testing new theories and exploring new high energy physics.

 

there is a new field of "Astroparticle Physics" with conferences and people specializing in it. It is people getting out of conventional HEP (High Energy Physics) and going into the high energy physics of GRB and CR and also I guess neutrinos which are interesting particle physics if not so high energy.

 

One has to understand how these huge releases of energy happen and what the particle reactions are and then what reactions go on when stuff hits our own atmosphere. One has to know what detectors to set up and all that.

 

So this is basic knowledge people want: what makes Cosmic Rays, and GRB too.

 

this was an invited talk at a conference---some credibility attaches to that.

---------here's the abstract--------

 

"There is mounting evidence that long duration gamma ray bursts (GRBs) are produced by ultra-relativistic jets of ordinary matter which are ejected in core collapse supernova (SN) explosions. Such jets are extremely efficient cosmic ray (CR) accelerators which can accelerate the swept up ambient particles on their way to the highest observed CR energies. The bulk of the jet kinetic energy is used to accelerate CRs while only a tiny fraction is used to produce the GRB and its afterglow. Here we use the remarkably successful cannonball (CB) model of GRBs to show that the bipolar jets from SN explosions, which produce GRBs most of which are not beamed towards Earth, can be the main origin of cosmic rays at all energies. The model explains very simply the elemental composition of CRs and their observed spectra at all energies. In particular it explains the origin of the CR knees and ankle. Above the CR ankle, the Galactic magnetic fields can no longer delay the free escape of ultra-high energies CRs (UHECR) from the Galaxy, and the CRs from the intergalactic medium (IGM), which were injected there by SN jets from all the galaxies and isotropized there by the IGM magnetic fields, dominate the Galactic CR spectrum. A Greisen-Zatsepin-Kuzmin (GZK) effect due to the interaction of UHECRs with the microwave background radiation is expected. The CR nuclei which diffuse out of galaxies, or are directly deposited in the IGM by the relativistic SN jets, may be the origin of the IGM magnetic fields. Inverse Compton scattering of the cosmic microwave background radiation (MBR) by the CR electrons in the IGM produces the diffuse extragalactic gamma-ray background radiation (GBR)."

--------end quote-----

 

Invited talk at Conference on Frontier Objects in Particle Physics and Astro Physics, Vulcano, Italy, May 24-29, 2004

 

Anybody want to put this in simple terms? what makes this high energy sh*t rain down from the sky? Sometimes a single particle can be carrying amazing amounts of energy----way more than you get from human-built accelerators----what process could accelerate stuff to such levels.

[Thales]

Just a quick question, if the cosmics rays are coming down at rates much faster than the particle accelerators, and they're flux is dictated somewhat by the earths magnetic field, can we somehow better study high energy particle physics with a satellite? I'm sure it would be no small engineering feat, but seeing as particle accelerators have limits based on their overall path length and these cosmic rays, are a bit father along the road, wouldn't it be cheaper in the long run?

[Martin]

Just a quick question, if the cosmics rays are coming down at rates much faster than the particle accelerators, and they're flux is dictated somewhat by the earths magnetic field, can we somehow better study high energy particle physics with a satellite? I'm sure it would be no small engineering feat, but seeing as particle accelerators have limits based on their overall path length and these cosmic rays, are a bit father along the road, wouldn't it be cheaper in the long run?

 

I am sure you can figure the basic differences----it is two different approaches and the accelerator has some clear advantages

you have a beam you can repeat something millions of times

you can set up a specific target and

an specific array of detectors

you can automate the counting of just the event you want

 

observing what comes down from the sky, by contrast, is haphazard

and imperfectly localized, statistical inference is more difficult

 

but there are a number of ambitious projects underway or planned.

 

the success of the neutrino observatories (under Antarctic ice, using huge tanks of heavy water and other liquids, in abandoned mines etc.)

has been dramatic

 

there is a trend I think towards observing the weird stuff from the sky with larger and more exotic detectors

 

it has been proposed to put up a bunch of satellites to look down at our upper atmosphere and detect flashes caused by particles from space crashing into the upper air------incredibly enough, observing neutrinos this way may be possible. (just as in a cubic kilometer of ice in Antarctica, where they also look for flashes)

 

this is pretty boggling, at least for me

 

there is an expert on all kinds of high energy CR and Gammaray observation named Floyd Stecker

and he has a survey article about what has been done and what is planned

the article is called, IIRC, "Cosmic Physics: The High Energy Frontier"

you might search arxiv.org, in the astro-ph department, by author Floyd Stecker.

 

[edit: I found the paper. it is http://arxiv.org/astro-ph/0309072]

[Martin]

Thales, one thing Stecker says is that cosmic rays have been observed with energies as high as 300 E18 eevee

that is something like a carbon nucleus whizzing along with several joules of kinetic energy

(a joule is 6E18 or 6 quintillion eevee)

 

Reflect that accelerator energies are measured in Tev

or trillion eevee.

 

so the very high energy cosmic rays are particles or nuclei whizzing with

energy that is on the order of a million times greater than what one gets in man-made accelerators.

 

meanwhile in accelerator world one struggles tooth and nail, and makes heroic efforts to secure funding, just to raise the energy a few tens of percent.

 

Stecker is a gentleman and makes no such comparison.

 

It is a good paper, I urge you to have a look.

 

His figure of 300 quintillion eevee corresponds to 50 joules. I also had heard this 50 joule figure elsewhere. It is incredible to me that a little thing like a proton or the nucleus of an atom could be hurtling so fast that it could have even one joule

(enough to raise a kilogram weight up 10 centimeters!)

 

50 joule is to raise a kilogram weight up by 5 meters! how could a such a thing have such energy! but there it is---on rare occasions sees UHECR (ultrahigh energy CR) with 300 E18 eevee.

 

------------------

Stecker also gives an upperbound on observed energies of Gammaray.

 

they go up to 50 TeV...

well visible light is on the order of 1 eV-----several eV like 3 IIRC.

the thermal light at the core of the sun is X-ray----around 1000 eV

so 50 TeV light is like the light you would get glowing from something that

is a billion times hotter than the core of the sun.

 

some light. I can't picture what could emit a photon of light with 50 TeV.

 

and cosmic gammaray comes in the sudden huge flashes called Gammaray Bursts.

so there is a lot to explain-----I hope this guy Arnon Dar really has

some adequate explanations----Stecker doesnt explain he just gives data and describes the ongoing efforts to get data.