by Jill Sakai, University of Wisconsin
Though still under construction, the IceCube Neutrino Observatory at the South Pole is already delivering scientific results — including an early finding about a phenomenon the telescope was not even designed to study.
- This “skymap,” generated in 2009 from data collected by the IceCube Neutrino Observatory, shows the relative intensity of cosmic rays directed toward the Earth’s Southern Hemisphere. Researchers from UW-Madison and elsewhere identified an unusual pattern of cosmic rays, with an excess (warmer colors) detected in one part of the sky and a deficit (cooler colors) in another.
IceCube captures signals of notoriously elusive but scientifically fascinating subatomic particles called neutrinos. The telescope focuses on high-energy neutrinos that travel through the Earth, providing information about faraway cosmic events such as supernovas and black holes in the part of space visible from the Northern Hemisphere.
However, one of the challenges of detecting these relatively rare particles is that the telescope is constantly bombarded by other particles, including many generated by cosmic rays interacting with the Earth’s atmosphere over the southern half of the sky. For most IceCube neutrino physicists these particles are simply background noise, but University of Wisconsin-Madison researchers Rasha Abbasi and Paolo Desiati, with collaborator Juan Carlos Díaz-Vélez, recognized an opportunity in the cosmic ray data.
“IceCube was not built to look at cosmic rays. Cosmic rays are considered background,” Abbasi says. “However, we have billions of events of background downward cosmic rays that ended up being very exciting.”
Abbasi saw an unusual pattern when she looked at a “skymap” of the relative intensity of cosmic rays directed toward the Earth’s Southern Hemisphere, with an excess of cosmic rays detected in one part of the sky and a deficit in another. A similar lopsidedness, called “anisotropy,” has been seen from the Northern Hemisphere by previous experiments, she says, but its source is still a mystery.
“At the beginning, we didn’t know what to expect. To see this anisotropy extending to the Southern Hemisphere sky is an additional piece of the puzzle around this enigmatic effect — whether it’s due to the magnetic field surrounding us or to the effect of a nearby supernova remnant, we don’t know,” Abbasi says.
The new result publishes Aug. 1 in The Astrophysical Journal Letters, published by the American Astronomical Society.
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asmilwho says:
July 30, 2010 at 10:46 pm
Anna V says “It would be interesting, with regard to Svensmark’s hypothesis, to see whether cloud cover correlates with this anisotropy. ”
I think the rotation of the earth once every 24hours will smear out any effect from this cosmic anisotropy
My error, you are right, it is a sky map they are showing not an earth map.
Michael Schaefer says:
July 31, 2010 at 4:06 am
Well,to me this picture looks like they have finally found scientific evidence for the Big Bang insofar, as the red – hot – area may show the direction to the center of the Universe i.e. the point, where the Big Bang actually happened – while the blue, cold area looks just the other way, i.e. away from the center of the Universe.
Not really.
One of the awe inspiring revelations when studying the expansion of the universe from the big bang point is that the center of the universe is everywhere. In other words, each point in the universe is the center of the universe. The expansion is not happening from a space time center outwards, but is the analogue of the two dimensional surface on an expanding balloon, all points recede from each other.
I work at SNOLAB. As Dr Marek Kos mentioned in a recent BBC article, “[SNOLAB] is at 6,000m water equivalent – a figure that’s used to compare it to other experiments – but it’s about 2km underground in the Canadian Shield.” Hot spots of cosmic rays makes sense to me. There seems to be a bit of a band in the graphic which I would suspect would map out to the milky way. — John M Reynolds
“[…] their newly reported findings rule out some proposed theories about the source of the Northern Hemisphere anisotropy.” – http://www.news.wisc.edu/18256
The map needs coordinates. A polar view would also be helpful – along with at least a brief note about temporal variability (but perhaps they have no info on that yet).
Michael Schaefer says:
July 31, 2010 at 4:06 am
…….But, of course, nobody would listen to me, like always… “SIGH!”
I fully understand how you feel. I am FULLY QUALIFIED to portray a Doctor on television. Even so, “they” have conspired against me to deny me the right to prescribe drugs!
Sigh!
Dave Springer says:
July 31, 2010 at 3:56 am
“There are more things in heaven and earth, Horatio, Than are dreamt of in
your philosophy.” Hamlet, Act I Scene V
Dave, This should be posted on the wall of every lab and office of every so-called “scientist”.
Steamboat Jack (Jon Jewett’s evil twin)
John McKay says:
July 31, 2010 at 5:04 am
“[…]Singularities don’t have centres. […]”
Tell that to Chandrasekhar.
Instead of calling it a sky map (sky being visible effects of the atmosphere), it would be better to call it a star map, or better, astronomic map.
> Presumably the skymap is made up of snapshots every 24h.
That would likely only work if the detector was at the south pole. Neutrino detections are so rare that I’d be amazed if they didn’t run full time, so presumably the map is right ascension vs. declination and synced up with the Earth’s sidereal rotation of 23 hours, 56 minutes, the time for a star to appear in the same location of the “sky”.
One probable correction – the cosmic ray events are likely not neutrinos, but muons created by cosmic rays hitting nuclei of atmospheric gases. Some of the high energy events create muons that can penetrate deep enough underground to interfere with neutrino detectors. They’re likely still counting individual muons, or at least showers from individual cosmic rays.
See also
http://www.sciencedaily.com/releases/2009/01/090121091228.htm
http://www.hep.umn.edu/soudan/brochure.html
http://iopscience.iop.org/0370-1328/87/1/311
asmilwho writes:
I think the rotation of the earth once every 24hours will smear out any effect from this cosmic anisotropy
Maybe,
but isn’t it possible that the anistrophy could have an effect even so, because it might, for example, hit (shine on) a warm ocean during the day one part of the year but hit that ocean the during the night another part of the year?
Cosmic ray flux is moduleted by a variety of factors, including 24 hours, solar magnetic field, etc. This article is correcting for these factors and basically making a static map of the sky. For an in depth explanation see:
http://www.atnf.csiro.au/pasa/18_1/duldig/paper/node5.html
Yup. The solar system wanders above and below the galactic plane cyclically over a period of time I don’t recall offhand.
It also doesn’t orbit the center of the galaxy at the same rate as the galactic arms so it traverses them at predictable times too. I believe the crossings are separated by millions of years so we shouldn’t expect any significant change from that measured in timeframes measured in tens or even hundreds of human generations.
Presumably when the solar system traverses a region where there are more stars per cubic parsec it will experience a commensurate increase in cosmic rays.
But who knows what invisible clouds or jets of limited width the solar system might move through on shorter timescales.
It sure would be nice to see the northern hemisphere part of this map. Sort of looks like the interference pattern of two or more sources.
I am not sure how to read the map ,
Which land mass is mostly above the “cooler area”?
Pool says:
I am not sure how to read the map ,
Which land mass is mostly above the “cooler area”?
See the comments above–it is not a map of earth (rotating every 24hrs), but of the sky, so it seems to me it would be more appropriate to ask “which constellations correspond with the cooler and warmer areas?
J says:
July 31, 2010 at 9:09 am
.. “which constellations correspond with the cooler and warmer areas?”
J, yup, that’s the question!
Leif, are you somewhere around?
Let´s be aware that CR are mainly (90%) composed of PROTONS, and these are not a shower of little pebbles, as the current “flitstones” universe believers may suppose, but HYDROGEN NUCLEII, so having the ability of reacting with ozone and oxygen to form WATER.
The the former “Aquarius Age” ( Aquarius is usually represented by a lady pouring a jug full of water…on our head), about 12,000 years ago. Ask Noah! 🙂
So…the ice-cube making machine is located down there!
Ric Werme says:
July 31, 2010 at 6:03 am
That would likely only work if the detector was at the south pole.
It is at the South Pole!
From a comment on another blog at:
http://www.physorg.com/news199468476.html
It appears likely that the sky map repredents 2 years worth of data.
Paper on Ice Cube (more info than you could ever want):
here:
http://arxiv.org/abs/1007.1247
Okay fine — but what time of day, …and standard time or daylight savings?
According to H.Svensmark GCR always mean clouds increase, and ….as protons react with ozone and oxygen more exogenic water:
pat says:
July 30, 2010 at 11:33 pm
Now isn’t this interesting. Hmmm.
ahhh, the most fundamental phrase of scientific discovery!
antonyindia says:
July 31, 2010 at 3:14 am
I wonder if anyone has restored any of the SUVs of model year 2537m.
Is this new work connected to what is already known about Cosmic Microwave Background anisotropy eg see here and here?
Lucy Skywalker says:
July 31, 2010 at 6:31 pm
Is this new work connected to what is already known about Cosmic Microwave Background anisotropy eg see here and here?
Well, in the sense that finally unexplained anisotropies could question the big bang theory, yes. As I said, the expansion of the universe according the big bang theory has no direction in 3 dimensions , and assumes the monotonic passage of time.
All points in the universe are from where the big bang started. Like points on the surface of an expanding balloon, they all recede from each other uniformly.
The evident anisotropies introduced by the existence of galaxies and galaxy clusters are explained as statistical fluctuations in the original energy soup.
I see no problem in finding a reason for these high energy events, in the 20TeV, range to be anisotropic, coming from some specific source, galactic or extragalactic. This is in contrast to the microwave background that,because it is so cold, is hypothesized to come from the beginning of the universe, and should be isotropic.
Ric Werme says:
July 31, 2010 at 6:17 am
“the cosmic ray events are likely not neutrinos, but muons”
Beg to differ: Neutrinos have no charge; muons are negatively charged. There is an absolute difference in how they are detected.
Further, neutrinos do not create atmospheric clouds (because a. they are not charged and b. do not interact with atmospheric molecules) and neutrinos have absolutely nothing to do with cosmic microwave background.
So this is much ado about nothing.