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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.
Welley Corporation - SLM Scammers
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?
...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?
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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.
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
... how the "cosmic rays" can make Mr. Fantastic so stretchy.
They didn't. Cosmic rays just activated the x-factor in the fantastic four, which would have stayed dormant otherwise, because they weren't mutants.
"Normal" mutants get their x-factor activated naturally, during the teen years.
(OMG, I can't believe I knew that)
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
...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.
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.
Find free books.
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"!
Arguing about vi versus Emacs is like arguing whether it's better to make fire by rubbing sticks or banging rocks.
I don't think he is confused, just over simplifying.
Via pair production, gamma rays produce the same kinds of secondary particle showers that the far more common primary cosmic rays do. However, because of momentum conservation, the particle shower is much more tightly focused and produces a distinctive Cherenchov cone that allows gamma rays particle showers to be easily distinguished from cosmic ray showers.
As noted in the article, the fact that gamma are currently being produced in the supernova remnant strongly argues that cosmic rays are also being accelerated there. The physics for this was proposed long ago, but no one has been able to directly measure it.
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.)
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
here. They even have a picture.
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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.
Friends don't help friends install M$ junk.
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
RXJ 1713-39, the SNR in question, is believed to about 1kiloparsec away, which corresponds to 3260 light years. When we say it is believed to be 1000 years old, that means it would have been seen at the earth 1000 years ago. It is actually possibly 4000 years old, but may be older. It is quite hard to determine the distance to these things unless one saw them explode.
What we see now is 1000 years after it exploded, so we just call it 1000 years old for simplicity.
The shell should be too old and dispersed to emit gamma rays by the time it reaches the earth.
First question, yes, it is possible to do that, especially for younger SNRs (up to a few hundred years maybe). For older ones, such as RXJ 1713 its harder as its more difficult to discern expansion.
The second point refers to SN 1987a, which was observed to explode 17 years ago (hence the name).