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Origin of Cosmic Rays Revealed
neutron_p writes "An international team of astronomers has produced the first ever image of an astronomical object using high energy gamma rays, helping to solve a 100 year old mystery - an origin of cosmic rays. The astronomers studied the remnant of a supernova that exploded some 1,000 years ago, leaving behind an expanding shell of debris which, seen from the Earth, is twice the diameter of the Moon. Cosmic rays are extremely energetic particles that continually bombard the Earth, thousands of them passing through our bodies every day."
They're coming from inside your house! Get out of your house!
"Cosmic rays are extremely energetic particles that continually bombard the Earth, thousands of them passing through our bodies every day." I feel so Violated.
The Cosmos?
Not with my handy-dandy tinfoil hat.
here.
Enjoy.
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Cosmic rays are extremely energetic particles that continually bombard the Earth, thousands of them passing through our bodies every day."
You mean it's like intergalactic spam?
"Cosmic rays are extremely energetic particles that continually bombard the Earth, thousands of them passing through our bodies every day."
WHAT??! We need to BAN THEM, like NOW!
...of cosmic ray air-showers.
Thousands of cosmic rays do not pass through our bodies every day... They are stopped by the atmosphere. Cosmic rays are actually fairly dangerous radiation. During the Apollo missions, Astronauts would occasionally see flashes of light as cosmic rays hit their eyes... they also left 'streaks' in the porthole glass.
I think you are confusing them with neutrinos, but even then you are wrong... billions of those pass through us every second.
In a way, it makes sense that they'd be partly responsible for the blue in our atmosphere -- the rest comes from the Sun bombarding the layers of gases up there. Sometimes science is just a way of jerryrigging loose facts together to create a plausible test or explanation for strange phenonema.
Try not. Do or do not, there is no try.
-- Dr. Spock, stardate 2822-3.
What is more interresting than a source of cosmic rays is the source of the gamma bursts. Some background is here.
Space has a terrible power. We are here to protect you from the terrible secret of space. Do you have stairs in your house?
Pak chooie unf.
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They are called muons. There is a lot more than a thounsand per day! And they can do A LOT of damage. Oh, and muons are produced from cosmic ray interractions in the upper atmosphere.
These things are very powerful. The Russians have been conducting experiments on the sea floor for years and lots of them are energetic enough to go through. It's been assumed for a while that supernovas are the source of cosmic rays but it has been hard to pinpoint their origin, since cosmic rays can be deflected by magnetic fields.
Wow, you enjoy looking at goatse enough to have noticed that he has a wedding ring?!
"[Regarding the 'cloud,'] ownership was what made America different than Russia." -- Woz
What's the highest frequency EM raidation that can be detected/measured with the technology we have today?
Could there be massive amounts of EM radiation flying around the universe that is simple undetectable? Could this not be the "missing mass" that is conjectured in discusions of universal inflation and what not?
Anyone know?
an expanding shell of debris which, seen from the Earth, is twice the diameter of the Moon [unattributed quote from the original article]
So its diameter is a function of viewing position. Sounds like angular diameter. That's still huge, though not as huge as M31 in Andromeda.
... how the "cosmic rays" can make Mr. Fantastic so stretchy.
Now that we've veered off onto neutrinos, let me point out how unbelievably cool neutrino detectors are. Start your journey via Google Images.
Here's what I do: Bitty Browser & Andromeda
This has, along with semi-conductor material and process defects etc., led to the whole field of Error Correcting Codes in computers - where such kind of errors can be prevented by things such as parity bits and what not. This works on the presumption that the probability of such bitswaps occurring on two bits is very small compared to just 1 bit. So, high-reliability computing servers etc. always tend to use memories with good ECC.
I have heard anecdotal evidence that IBM did some thourough testing of how such a behavior of bit-flipping due to cosmic rays changes at different elevation. When the elevation was high (7000 feet or so) - it occurred far more often then at the sea level. They did such tests below the surface of the earth and as they went deeper into the earth - such cosmic rays bit-flipping effect decreased but still remained. Only, after they went something like 40 feet or so below the surface of the earth - such behavior completley went away.
So, next time you wonder why you are paying more for ECC-RAM - think of cosmic rays (and material defect and what not ...)
Osho
No, it's just that he's wearing the matching ring.
Went looking around for more information, and came up with this:
s p?id=15U3&
http://www.pparc.ac.uk/frontiers/archive/update.a
It includes a picture of the telescope array as well as a small image of the gamma ray map.
liqbase
[In Eyeore intonation, with a heavy heart]:
"I, for one, welcome our new supernoverlords."
There. Somebody had to.
...I have a web page describing how: here
-- SIGFPE
((1000 light-years)*(size of moon))/(moon orbital height)
across,
((9.5 × 10^18 meters) * (3,476,000m))/ (384,403,000 m)
That's about 86 light years in diameter. Its average velocity is left as an exercise to the homebound.
sigs, as if you care.
Make that 172 light years in diameter.
sigs, as if you care.
I was involved in a similar, but very much smaller scale, experiment for my MSc thesis (JANZOS), attempting to find detect gamma rays from the (then very recent) supernova 1987A in the Large Magellanic Cloud.
So supernovae were a prime suspect source back then.
We had three (not four) 2 metre (not 12 metre) telescopes with about 30 'pixels' each (compared to a few thousand for HESS.) (I actually worked on another part of the experiment, which used particle detectors to detect higher energy showers.)
A significant problem is to distinguish between showers created by gamma rays and ones created by charged particles (mostly protons.) The charged particle showers are 'uninteresting', because the direction they come from is uncorrelated to their source - they move on curved paths due to galactic magnetic fields. Unfortunately, they are about 99% of the cosmic rays. We were not able to distinguish, so we had a large 'signal to noise' problem.
There was a single telescope similar to these ones in the mid 80s (the Whipple Telescope, I think) which claimed to be able to distinguish by details of shower structure. (We didn't have the resolution, nor perhaps the light gathering power, to make use of this.) I presume HESS has built on this work.
Note that this result does not necessarily tell us about the very highest energy cosmic rays. There is a change in the slope of the spectrum at (from memory) about 10^15 electron volts, so it is likely that different processess are involved on either side of this boundary. I think there were also theoretical reasons to think that supernovae could not accelerate particles to such high energies.
As I recall, the models for acceleration generally required shock waves in a gas with magnetic fields. Particles could repeatedly bounce across the shock, getting accelerated each time. (Think of a ball bouncing between two walls that are moving towards each other.)
Quattuor res in hoc mundo sanctae sunt: libri, liberi, libertas et liberalitas.
- Gamma rays are not cosmic rays
- Gamma rays do not cause Cherenchov radiation
Primary cosmics rays are subatomic particles with extremely high energy. The most energetic ones have an energy comparable to the energy of a tennis serve.Much like your own DNA.
We all think that mutations happen daily, but that is far from the case. In fact genetic mutation is very rare because we have error correcting enzymes which travel back and forth on DNA strands correcting them as they change. Typically the DNA "code" is changed as subatomic particles rip through your body, just as you've explained with RAM.
Yes, our DNA mutates. It doesn't stay that way however. Statistically there are more errors in a 300 page book then in a mile long DNA sequence. Actually there are about 0 errors in DNA because of this self-correcting mechanism.
* Source: Shadows of Forgotten Ancestors by Ann Druyan and Carl Sagan.
Get your Unix fortune now!
A long time ago (early 80s) I worked in a lab that used scintillation counters to measure biological activity (Background: you'd put a radioactively labelled (eg with tritium or C14)reagent in with the other cocktail for a test you're conducting in a little test tube. After say 5 mins you'd stop the reaction (say with perchloric acid), syphon off the top layer and put it into scintillation liquid (not sure what it was, but largely based on toluene) and put the vials into the scintillation counter which would have hundreds of little tubes in a conveyor belt and one by one drop the tubes deep inside the lead shielding to measure flashes of light as the isotopes decayed, hence telling you v accurately how much of the original substance under test had bound to the labelled reagent).
Anyway, every few days the counter would go completely stupid, and every few weeks copletely bananas (a technical term). It turned out the major machine crashes coincided with all scintillation counters in the building going crazy at the same time. We had over a dozen of these machines (all different brands) and they had about 6inches of lead around the detectors, so that was quite some energetic particles we were getting. The all the manufacturers' reps said there was little we could do to fix this, unless we wanted to be underground.
Talking to a friend at the local uni cosmic ray observatory (500+ scintillation counters spread over about a square kilometer), he said the more energetic showers were smaller in radius as the particles have less time to spread out from the initiating collision of a cosmic particle with the upper atmosphere. Usually they spread out to 50 to a few hundred metres across, with a massive cascade of all sorts of particle by the time it reaches ground level.
Interestingly, the initial byproducts of cosmic ray collisions have a v short life which means they should decay before reaching sea level. However as they travel close to the speed of light the depth of the atmosphere is foreshortened (Lorenzian contraction) to only a few hundred metres deep - a simple proof of relativity in action (or likewise, time is going slower for the cosmic particles).
It has been said that cosmic rays are the largest contributor to genetic mutations, beyond background radiation levels due to radioactive isotopes occuring naturally in the ground. Similarly, work place studies show airline hostesses/stewards have the far largest dosage of radiation of any occupation as they spend so much time above the bulk of the atmosphere. (Pilots spend less time in the air due to safety/fatigue regulations).
I also recall reading that it's extremely difficult to work out where cosmic rays originate as they are usually charged particles that follow curved paths through space due to the small but significant magnetic fields of stars and the galaxy itself. Due to timing of shows hitting detectors we can easily measure the angle a particle was going when it hit the atmosphere, but the particle took a very convoluted path prior to that, so finding a close source (100ly) is significant.
pithy comment
The cosmic rays that the article discusses are not muons, they are most often protons. The muons are what we encounter on Earth. The proton (also called the primary cosmic ray) comes in, hits our atmosphere, and a shower of subatomic particles is produced. The muon is the most powerful of these subatomic particles that is commonly produced. The fact that muons have a short half-life, and yet they can still reach us, has been cited as proof of relativity, and the idea that when you travel close to the speed of light (which these things do), time will slow down.
This is NOT the first gamma-ray image. I work on Glast which is the second generation of gammay observation satelites. EGRET was the most recent satelite to provide gamma-ray skymaps. Googled
The group's publications page is here (click on observations section), but they don't seem to have a preprint of this paper. Nature will let you read the abstract of the paper for free.
The research seems to be just a more direct confirmation of something that was already thought to be understood, but had never really been verified.
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Don't worry - cosmic rays are a great source of super-powers such as stretchiness, spontaneous combustion, invisibility, and...and...Things.
I'm surprised noone else caught the Fantastic Four reference in the "from the...department" line of the summary - it was the first thing I thought of when I saw the phrase "cosmic rays"!
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It's people!!! Cosmic rays is people!!
These heavily charged extremely small particles have the property that they change the capacitance of parts of semiconductors when passed through them.
Close but no cigar.
The rapid passage of a charged particle deposits enough energy on nearby charged particles to jog them out of place - creating a sudden conductive sea of electron-hole pairs. These charge carriers are then swept away by the local field, becoming a burst of current.
This affects memory and logic devices in two ways:
1) It can suddenly leak away the charge stored in the capacitance of a dynamic RAM.
2) It can momentarily turn "on" a transistor that should be off (even turning it more "on" than it normally would be, so its conduction swamps that of its turned-on partner in a totem-pole stage.)
Leaking the stored charge in a RAM flips the bit - in a particular direction. Turning on a transistor that should be off may flip a bit in a flop. latch, or static RAM, or momentarily cause the wrong level on a logic line.
Nothing to do with changed capacitance (although the sudden appearance of an extra conductive region does represent an increased capacatance on some nearby conductors).
Cosmic rays (fast charged nuclear fragments) can do this. Another problem was alpha particles from heavy elements in the ceramic integrated circuit packages once used for memory and mil-spec ICs (which is why they disappeared). A third was alpha particles from the decay of radon gas. (Turns out some locations in Silicon Valley have a lot of radon.)
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here. They even have a picture.
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It's funny that "origin" in this case is "where they're coming from" when the real question is "why and how are cosmic rays created?"
There's a lot of energy being beamed about, and well, you'd think that it would stop eventually, but it keeps on coming.
http://www.technewsworld.com/story/36324.html/
... An electronic voting machine error in a May, 2003, election in Belgium produced just over 4,100 more votes for the winner than there were eligible voters. .... a cosmic ray perfectly timed and directed to smite the memory cell holding the 13th bit of the total for the microsecond it was stored prior to printing.
Le rayon cosmique qui a touché la mémoire d'une des urnes électroniques de Schaerbeek, ce rayon cosmique permettra de sensibiliser des députés encore acquis au vote électronique.
The official review reduced this to exactly 4,096 extra votes and was therefore able to conclude that
Cosmic Radiation makes up about 8% of the 360 mREM annual average background dose someone in the US receives. See the National Council on Radiation Protection and Measurements NCRP 93, 1988, for more information. Murray's "Nuclear Energy" has a pie chart of all sources and might be in your local library. This looks good too.
If you have a Sodium Iodine detector set and a scope, you can see it. Most common energies seen are around 20 MeV. They are big pulses next to the puny normal ones but you will detect one every twenty seconds or so.
You are correct, however, to note that most of these particles are blocked by the atmosphere and that you do get dosed at higher elevations. A person at 80,000 ft. according to the lesson plan cited above, gets about 10 R/hr. Each hour that's five hundred times the dose you get per year on the surface, ouch. By comparison, plants have a cow if you get more than a few unplanned mR.
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I'm suddenly feeling stretchy...
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Even though they are extemently energetic, they tend to do very little harm since:
1) The charged particle component of cosmic rays is sheilded by the Earth's magnetic field
2) The uncharged (neutron) component of cosmic rays does not interact with matter very much - it is very penetrating simpley because it passes through most matter without colliding with anything.
3) Gamma rays, like neutrons, tend to pass though quite a bit of matter without actually interacting with it.
Or more simply, we are transparent to alot of the radiation that does reach us.
"If you'd had been listening, you'd know nintendos pass right through you" - Jack O'Neill
Since I work for this experiment, I guess I should try to clear up a few points which have been discussed here.
A Supernova remnant (SNR) is a very rapidly expanding bubble of hot gas, created by the explosion of a massive star. It is thought that the shock wave caused by these expanding bubbles in our galaxy accelerate surrounding hydrogen gas to very high energies, which then become the cosmic ray protons which we see at the earth today. Protons form the bulk of the cosmic ray flux between MeV and EeV energies, and at least up PeV energies they seem to be formed in our Galaxy, probably by SNRs.
The SNRs are really light years across, the ones we see are generally in the local quadrant of our galaxy, thus are really not far away in the cosmic scale of things. Happily not close enough to fry us though! Cosmic redshift does not occur within our galaxy, by the way.
We detect gamma rays at very high energies by looking at their interactions with the upper atmosphere. The gamma rays themselves do not generally penetrate to the ground, we measure the Cherenkov light emitted by the shower of charged paticles which stem from the gamma ray interaction.
One reason gamma rays are interesting is that they , like other photons, travel directly to us from their source, so we can use them to make pictures of what the source looks like. We believe in this case that the gamma rays are produced in the supernova remnant by interactions of the accelerated protons, and thus are a tracer which proves the existence of the comsic rays at the SNR, and thus that SNRs generate cosmic rays.
The particles which pass through us every day are mostly muons, which are by-products of the interaction of cosmic ray protons with the atmosphere.
More information can be found at:
http://www.mpi-hd.mpg.de/hfm/HESS/HESS.html
The article doesn't state how distant that supernova is/was, only that it happened 1,000 years ago. Does that mean the supernova explosion was observable from Earth 1,000 years ago (saying nothing about its distance), or that the explosion actually happened 1,000 years ago (putting it at a distance of 1,000 lightyears)?
In either case, if the shell of debris has now travelled half a degree of angular separation from the original point of explosion (uniformly in all directions), I suppose that debris will eventually reach Earth when the shell has achieved an angular diameter of 180 degrees (if it has been expanding for 1,000 years, it would arrive here some 113,592 years from now). Hopefully the debris will then be diluted enough not to hit any sensitive parts of our solar system... Will that debris still be emitting gamma rays?
A few comments on your points aXis: 1) This is dependent on your geomagnetic position on Earth. The high energy cosmics go through it anyway and we are shielded from them by the atmosphere more than the weak magnetic field. 2)There's no neutrons in the primary cosmic rays since they decay AND neutrons *do* interact with matter a *lot*. The neutrons come from the interactions of charged particles with the atmosphere. They are the second highest dose inducer after muons at sea level, and the primary at an altitude of ~4km. You must be confusing them with neutrinos.http://www.triumf.ca/safety/rpt/rpt_4/no de3.html
3)There's not that many gamma-rays in the radiation that hits us on earth and they are mainly muons - which are charged particles and actually do some harm to us but not as much as the average amount of X-rays we get per year.
So the way I would put it is that we are transparent to the highest fluxes of particles (neutrinos) and that the radiation that reaches us from interactions of cosmic rays in the atmosphere induce lower doses than other ambient radioactivity sources..
Well, when two cosimc bodies really love each other... yadda yadda yadda... Big Bang... and the next thing you knwo they have little Cosmic Ray.