Banner
    Finding The Origins Of Cosmic Rays
    By News Staff | August 30th 2013 12:34 PM | 15 comments | Print | E-mail | Track Comments

    Cosmic rays, high-energy particles, can damage electronics on Earth, as well as human and non-human DNA, which puts astronauts in space at risk but has also caused any number of genetic modifications in plants that are considered completely natural.  

    Their origin has confounded scientists for decades. A study using data  collected by IceTop at the IceCube Neutrino Observatory at the South Pole, reveals new information that may help unravel the longstanding mystery of exactly how and where these "rays", because the more scientists learn about the energy spectrum and chemical composition of cosmic rays, the closer humanity will come to uncovering where these energetic particles originate. 

    Cosmic rays are known to reach energies above 100 billion giga-electron volts (1011 GeV). The data reported in this latest paper cover the energy range from 1.6 times 106 GeV to 109 GeV. Researchers are particularly interested in identifying cosmic rays in this interval because the transition from cosmic rays produced in the Milky Way Galaxy to "extragalactic" cosmic rays, produced outside our galaxy, is expected to occur in this energy range. 



    The cosmic ray energy spectrum, shows the steepening at the "knee." Below the knee, cosmic rays are galactic in origin; above that energy, particles from more distant regions in our universe become more and more likely. Credit: Bakhtiyar Ruzybayev/University of Delaware

    Exploding stars called supernovae are among the sources of cosmic rays here in the Milky Way, while distant objects such as collapsing massive stars and active galactic nuclei far from the Milky Way are believed to produce the highest energy particles in nature.

    As University of Delaware physicist Bakhtiyar Ruzybayev, the study's corresponding author, points out in the scientific figure (above) submitted to the journal, the cosmic-ray energy spectrum does not follow a simple power law between the "knee" around 4 PeV (peta-electron volts) and the "ankle" around 4 EeV (exa-electron volts), as previously thought, but exhibits features like hardening around 20 PeV and steepening around 130 PeV.

    "The spectrum steepens at the 'knee,' which is generally interpreted as the beginning of the end of the galactic population. Below the knee, cosmic rays are galactic in origin, while above that energy, particles from more distant regions in our universe become more and more likely," Ruzybayev explained. "These measurements provide new constraints that must be satisfied by any models that try to explain the acceleration and propagation of cosmic rays."



    Citation:  Aartsen, M. G. and Abbasi, R. and Abdou, Y. and Ackermann, M. and Adams, J. and Aguilar, J. A. and Ahlers, M. and Altmann, D. and Auffenberg, J. and Bai, X. and Baker, M. and Barwick, S. W. and Baum, V. and Bay, R. and Beatty, J. J. and Bechet, S. and Becker Tjus, J. and Becker, K.-H. and Benabderrahmane, M. L. and BenZvi, S. and Berghaus, P. and Berley, D. and Bernardini, E. and Bernhard, A. and Bertrand, D. and Besson, D. Z. and Binder, G. and Bindig, D. and Bissok, M. and Blaufuss, E. and Blumenthal, J. and Boersma, D. J. and Bohaichuk, S. and Bohm, C. and Bose, D. and B\"oser, S. and Botner, O. and Brayeur, L. and Bretz, H.-P. and Brown, A. M. and Bruijn, R. and Brunner, J. and Carson, M. and Casey, J. and Casier, M. and Chirkin, D. and Christov, A. and Christy, B. and Clark, K. and Clevermann, F. and Coenders, S. and Cohen, S. and Cowen, D. F. and Cruz Silva, A. H. and Danninger, M. and Daughhetee, J. and Davis, J. C. and De Clercq, C. and De Ridder, S. and Desiati, P. and de Vries, K. D. and de With, M. and DeYoung, T. and D\'\iaz-V\'elez, J. C. and Dunkman, M. and Eagan, R. and Eberhardt, B. and Eisch, J. and Ellsworth, R. W. and Euler, S. and Evenson, P. A. and Fadiran, O. and Fazely, A. R. and Fedynitch, A. and Feintzeig, J. and Feusels, T. and Filimonov, K. and Finley, C. and Fischer-Wasels, T. and Flis, S. and Franckowiak, A. and Frantzen, K. and Fuchs, T. and Gaisser, T. K. and Gallagher, J. and Gerhardt, L. and Gladstone, L. and Glusenkamp, T. and Goldschmidt, A. and Golup, G. and Gonzalez, J. G. and Goodman, J. A. and G'ora, D. and Grandmont, D. T. and Grant, D. and Groß, A. and Ha, C. and Haj Ismail, A. and Hallen, P. and Hallgren, A. and Halzen, F. and Hanson, K. and Heereman, D. and Heinen, D. and Helbing, K. and Hellauer, R. and Hickford, S. and Hill, G. C. and Hoffman, K. D. and Hoffmann, R. and Homeier, A. and Hoshina, K. and Huelsnitz, W. and Hulth, P. O. and Hultqvist, K. and Hussain, S. and Ishihara, A. and Jacobi, E. and Jacobsen, J. and Jagielski, K. and Japaridze, G. S. and Jero, K. and Jlelati, O. and Kaminsky, B. and Kappes, A. and Karg, T. and Karle, A. and Kelley, J. L. and Kiryluk, J. and Klas, J. and Klein, S. R. and Kohne, J.-H. and Kohnen, G. and Kolanoski, H. and Kopke, L. and Kopper, C. and Kopper, S. and Koskinen, D. J. and Kowalski, M. and Krasberg, M. and Krings, K. and Kroll, G. and Kunnen, J. and Kurahashi, N. and Kuwabara, T. and Labare, M. and Landsman, H. and Larson, M. J. and Lesiak-Bzdak, M. and Leuermann, M. and Leute, J. and Lunemann, J. and Maciias, O. and Madsen, J. and Maggi, G. and Maruyama, R. and Mase, K. and Matis, H. S. and McNally, F. and Meagher, K. and Merck, M. and Meures, T. and Miarecki, S. and Middell, E. and Milke, N. and Miller, J. and Mohrmann, L. and Montaruli, T. and Morse, R. and Nahnhauer, R. and Naumann, U. and Niederhausen, H. and Nowicki, S. C. and Nygren, D. R. and Obertacke, A. and Odrowski, S. and Olivas, A. and Omairat, A. and O' Murchadha, A. and Paul, L. and Pepper, J. A. and Perez de los Heros, C. and Pfendner, C. and Pieloth, D. and Pinat, E. and Posselt, J. and Price, P. B. and Przybylski, G. T. and Radel, L. and Rameez, M. and Rawlins, K. and Redl, P. and Reimann, R. and Resconi, E. and Rhode, W. and Ribordy, M. and Richman, M. and Riedel, B. and Rodrigues, J. P. and Rott, C. and Ruhe, T. and Ruzybayev, B. and Ryckbosch, D. and Saba, S. M. and Salameh, T. and Sander, H.-G. and Santander, M. and Sarkar, S. and Schatto, K. and Scheriau, F. and Schmidt, T. and Schmitz, M. and Schoenen, S. and Schoneberg, S. and Schonwald, A. and Schukraft, A. and Schulte, L. and Schulz, O. and Seckel, D. and Sestayo, Y. and Seunarine, S. and Shanidze, R. and Sheremata, C. and Smith, M. W. E. and Soldin, D. and Spiczak, G. M. and Spiering, C. and Stamatikos, M. and Stanev, T. and Stasik, A. and Stezelberger, T. and Stokstad, R. G. and Stößl, A. and Strahler, E. A. and Ström, R. and Sullivan, G. W. and Taavola, H. and Taboada, I. and Tamburro, A. and Tepe, A. and Ter-Antonyan, S. and G. Tešić and Tilav, S. and Toale, P. A. and Toscano, S. and Unger, E. and Usner, M. and Vallecorsa, S. and van Eijndhoven, N. and Van Overloop, A. and van Santen, J. and Vehring, M. and Voge, M. and Vraeghe, M. and Walck, C. and Waldenmaier, T. and Wallraff, M. and Weaver, Ch. and Wellons, M. and Wendt, C. and Westerhoff, S. and Whitehorn, N. and Wiebe, K. and Wiebusch, C. H. and Williams, D. R. and Wissing, H. and Wolf, M. and Wood, T. R. and Woschnagg, K. and Xu, C. and Xu, D. L. and Xu, X. W. and Yanez, J. P. and Yodh, G. and Yoshida, S. and Zarzhitsky, P. and Ziemann, J. and Zierke, S. and Zoll, M.,IceCube Collaboration, 'Measurement of the cosmic ray energy spectrum with IceTop-73', Phys. Rev. D » Volume 88 » Issue 4 DOI: 10.1103/PhysRevD.88.042004


    Comments

    so the 'ankle' is ABOVE the 'knee'?

    only if you hold the graph upside down.

    Oh, you mean in energy level.

    never mind.

    How do they know? Have they been there?

    Hank
    What does that mean? Have you been to Antarctica? Are you sure it is there?
    There are several typos here

    1011 GeV should be 10^11 GeV

    "energy range from 1.6 times 106 GeV to 109 GeV " is incomprehensible

    Above knee should be below knee and vice versa

    IF ANY OF THE "EDITORS" of this "blog" are actually paying attention, it comes down to this: YOU HAVE NO FREAKIN' CRED with the scientifically competent crowd and you fall farther off the edge of the map every time you allow a semi-literate, scientifically vacuous twittertard to author a piece like this and then hide behind the "News Staff" Byline.
    Thanks for wasting my time.

    Hank
    It was written by the University of Delaware. It's in the press release section, just like it says.
    Cosmic rays are known to reach energies above 100 billion giga-electron volts (1011 GeV). The data reported in this latest paper cover the energy range from 1.6 times 106 GeV to 109 GeV.
    is what they wrote. Did you truly not understand what they meant? You and 3 other people in the Science 2.0 audience would fail to grasp something obvious and 1 will rant about how awful science journalism is - except this isn't journalism, it is in the press release section. If press releases were perfect, it would mean too much taxpayer money is going toward writing press releases, which seems more wasteful.
    Since when is 100 billion the same as 1011? So, I guess we don't understand what they meant.

    Hank
    Sure, I get the confusion for some, the University of Delaware probably would get it, if they had a way to comment on their release. But no one who understands the energy spectrum was confused, since people look at the graph and don't much need to even read the release,  they probably just thought 'press release writer, go home, you're drunk again'.
    Sure, and you'd have a point if this site had only linked to the press release. However to cut and paste it, and then not even bother to do an editorial review? What's the point? Their mistake is on them, but when you copy it, then it falls on you too.

    Hank
    Again, the audience is not educated by these press releases, they just like to know what is going on out there. About 10,000 sites will have this exact same release, they are not copied and pasted, other by the person at the university who uploads them. When that does not happen, it is a parser.
    The abstract for the article is well written.
    This blog post interpretation of the abstract is poorly written.
    What's up with the phonebook of authors?

    Hank
    The abstract was written by the authors but this press release was written by an unspecified person at the University of Delaware. Someone always gets shafted when collaborations use a few authors and then et al, so the authors who likely did the bulk of the work probably appreciate that some site carrying this release did the citation export correctly.
    Does anybody ever READ this stuff? READ this sentence aloud:

    A study using data collected by IceTop at the IceCube Neutrino Observatory at the South Pole, reveals new information that may help unravel the longstanding mystery of exactly how and where these "rays", because the more scientists learn about the energy spectrum and chemical composition of cosmic rays, the closer humanity will come to uncovering where these energetic particles originate.

    My high school English teacher would have had red pencil all over the page!

    Take my advice, Tom, ignore the prattlings of your red-pencil-wielding teacher who, it would appear, had difficulty negotiating his or her way from one end of a sentence to the other without getting lost. In this case, it has to be said, there are some misleading signposts en route. However, readers are not mindless computers (debate) who can only parse a perfect sentence (don't debate). On the contrary, a recent discussion here raised the philosophical Principle of Charity, which, in simple terms, means you assume that the author has something sensible to say until it is proved otherwise and you make allowances. Obviously it gets irritating when some texter posts gibberish in all lower case without punctuation and full of ims (I am) & urs (you are) and other such atrocities.

    But (yes, I'm starting a sentence, a paragraph even, with a conjunction - so sue me) it is even more irritating when a pedant merely complains about the typos, spellos and grammos but has nothing to say about the *content* of a blog. A comma after "study" to match the comma after "pole", "data", "Top" or "observatory" would have helped us understand which of the many bits of information in the opening clause were intended to be parenthetical, but as there was probably no such intention at all, one may reasonably assume that the comma after "Pole" is superfluous. It was probably added by someone who thinks that commas are instructions where to take a breath when reading out loud. There again, maybe to some people a random scattering of commas looks decorative. Unfortunately, commas to mark off parenthetical phrases are becoming unfashionable even amongst educated writers, a move I deprecate as, whilst I can usually work out which bits of a sentence are intended to go with which other bits, a comma or two in the right place helps me feel confident that I am on the right track especially when the sentence looks like it is going to be a marathon with no prospect of the long-awaited full stop for as far as the eye can see. (Thank you Fowler.)

    Missing commas aside, the sentence merely needs the word "originate" added after "rays" (and no quotes around "rays" since these are proper rays, not so-called rays). Fussy critics will then object to the use of the word "originate" twice in the same sentence and, to be sure, the second one could be replaced by a synonym like "come from". So, by the simple addition of one word, the sentence then makes sense. In fact it could just about be argued that the sentence merely exhibits pathological ellipsis as it stands and that the one instance of the word is actually shared between both clauses. Just about.

    No, my principle objection to the sentence would not be the careless English, nor even the clumsy logic that A may help explain B because A helps explain B. Simply saying "information about the spectral and chemical composition of cosmic rays which" would obviously serve the same purpose and the author could then continue with the main thrust of the sentence which seems to be to gush fatuously about humanity's acheivements. That is what really grates with me. The vast majority of humanity live lives of illiterate poverty and wouldn't know a neutrino if it jumped up and bit them on the nose. Of those who are privileged enough to brush with a modicum of science, the vast majority are only interested in tweeting and getting drunk and do not care. Humanity's quest for knowledge is a Star Trek myth; the credit for unravelling the origin of cosmic rays does not go to the the vast hoard of ignorant hangers-on collectively known as humanity but to the particular scientists who do it.

    And Tom, if you have read this comment all the way through... you need to get out more! As do I :)

    Cheers