[如果进一步证实就是重大新闻]紫金山天文台的NATURE文章，发现

Science News 评论： ASTROPARTICLE PHYSICS: Excess Particles From Space May Hint at Dark Matter Adrian Cho An unexpected abundance of high-energy electrons from space could be evidence of particles of dark matter--the weighty and mysterious stuff whose gravity holds the galaxies together. The observation is the second in 4 months that suggests a link between cosmic rays and dark matter. But if the sightings really do point to dark matter, then physicists may have to revise their ideas about what the stuff is. The latest result comes from the Advanced Thin Ionization Calorimeter (ATIC), a NASA-funded balloon-borne particle detector that circled the South Pole. "If it is true, it's fantastic," says Lars Bergström, a theoretical astroparticle physicist at Stockholm University in Sweden. Using data collected in 2000 and 2002, ATIC researchers observed about 210 electrons and positrons with energies between 300 billion and 800 billion electron volts (GeV), they report this week in Nature. That was about 70 more than they expected by extrapolating from lower energies. The excess could be born of the collisions of dark-matter particles, says ATIC team leader John Wefel, an astrophysicist at Louisiana State University, Baton Rouge. According to leading theories, when two dark-matter particles collide, they should annihilate each other and produce either an electron and a positron or some other particle-antiparticle pair. The excess could also be produced by a nearby pulsar or other astrophysical beast that accelerates particles in some unexpected way. But "so far we have not been able to find anything out there that's able to do this," Wefel says. Moreover, the excess abruptly disappears at energies above 800 GeV. That detail might point toward dark matter, as the mass of the colliding dark-matter particles would limit the energy of electrons and positrons, Bergström explains. Going up? Researchers prepare ATIC to be hauled aloft by a balloon. The particle detector may have spotted signs of dark matter. CREDIT: T. GREGORY GUZIK/ATIC COLLABORATION Another cosmic-ray observation also hints at dark matter. In August, researchers with the orbiting PAMELA (Payload for Antimatter Matter Exploration and Light-Nuclei Astrophysics) experiment reported that at energies between 10 GeV and 100 GeV, the ratio of positrons to the sum of electrons and positrons begins to climb. Ordinarily, electrons from space should far outnumber positrons. But dark-matter annihilations should produce equal numbers of electrons and positrons, causing the ratio to rise, as PAMELA observed. The PAMELA and ATIC data are "completely compatible," says Marco Cirelli of the Institute of Theoretical Physics of the French Atomic Energy Commission in Saclay, France. "PAMELA is seeing the start of the rise [in electron-positron pairs], and ATIC is seeing the whole bump," he says. Ironically, if ATIC and PAMELA are detecting dark matter, then theorists may have to rethink a favorite idea. Many believe that dark-matter particles might be the lightest particles predicted by supersymmetry, which posits a heavier "superpartner" for every known type of particle. But colliding particles of supersymmetric dark matter ought to produce a lot of proton-antiproton pairs. Unless the supersymmetric particles are heavier than generally expected, PAMELA should also see the ratio of antiprotons to protons increase at energies above 10 GeV, which it doesn't. Moreover, annihilating supersymmetric particles won't directly produce electron-positron pairs, but it will make other particles that decay into the electron and proton. That should smooth over the sharp drop-off ATIC sees. "If this is dark matter, it is not the standard dark matter," Cirelli says. Clarity may come soon. NASA's Fermi Gamma-Ray Space Telescope, launched in June, will look for photons produced by dark-matter annihilations. If ATIC and PAMELA are seeing a real signal, then Fermi should see one, too.

Nature 原文连接： http://www.nature.com/nature/journal/v456/n7220/full/nature07477.html 鉴于版权原因，就只贴个摘要，不贴全文了 Nature 456, 362-365 (20 November 2008) | doi:10.1038/nature07477; Received 23 May 2008; Accepted 1 October 2008 An excess of cosmic ray electrons at energies of 300–800 GeV J. Chang1,2, J. H. Adams3, H. S. Ahn4, G. L. Bashindzhagyan5, M. Christl3, O. Ganel4, T. G. Guzik6, J. Isbert6, K. C. Kim4, E. N. Kuznetsov5, M. I. Panasyuk5, A. D. Panov5, W. K. H. Schmidt2, E. S. Seo4, N. V. Sokolskaya5, J. W. Watts3, J. P. Wefel6, J. Wu4 & V. I. Zatsepin5 1. Purple Mountain Observatory, CAS, 2 West Beijing Road, Nanjing 210008, China 2. Max Planck Institute for Solar System Research, 2 Max Planck-Strasse, Katlenburg-Lindau 37191, Germany 3. Marshall Space Flight Center, Huntsville, Alabama 35812, USA 4. University of Maryland, Institute for Physical Science & Technology, College Park, Maryland 20742, USA 5. Skobeltsyn Institute of Nuclear Physics, Moscow State University, Leninskie gory, GSP1, Moscow 119991, Russia 6. Louisiana State University, Department of Physics and Astronomy, Baton Rouge, Louisiana 70803, USA Correspondence to: J. P. Wefel6 Correspondence and requests for materials should be addressed to J.P.W. (Email: wefel@phunds.phys.lsu.edu). Top of page Abstract Galactic cosmic rays consist of protons, electrons and ions, most of which are believed to be accelerated to relativistic speeds in supernova remnants1, 2, 3. All components of the cosmic rays show an intensity that decreases as a power law with increasing energy (for example as E-2.7). Electrons in particular lose energy rapidly through synchrotron and inverse Compton processes, resulting in a relatively short lifetime (about 105 years) and a rapidly falling intensity, which raises the possibility of seeing the contribution from individual nearby sources (less than one kiloparsec away)4. Here we report an excess of galactic cosmic-ray electrons at energies of approx300–800 GeV, which indicates a nearby source of energetic electrons. Such a source could be an unseen astrophysical object (such as a pulsar5 or micro-quasar6) that accelerates electrons to those energies, or the electrons could arise from the annihilation of dark matter particles (such as a Kaluza–Klein particle7 with a mass of about 620 GeV).

我晕 只看了题目。。。开完会回来仔细研究一下～～ 【 在 aressong (馨雨) 的大作中提到: 】 : http://www.astron.sh.cn/2008/news.asp?id=382 : 紫金山天文台发现暗物质粒子湮灭的可能证据 : 天文信息 2008-11-20 : ...................

这太n了 【 在 aressong (馨雨) 的大作中提到: 】 : http://www.astron.sh.cn/2008/news.asp?id=382 : 紫金山天文台发现暗物质粒子湮灭的可能证据 : 天文信息 2008-11-20 : ...................

n！=2 【 在 IkariShinji (轉型|[路]團長|碇シンジ|The 3rd Child) 的大作中提到: 】 : 这太n了

好强大，看不懂的说 【 在 aressong (馨雨) 的大作中提到: 】 : http://www.astron.sh.cn/2008/news.asp?id=382 : 紫金山天文台发现暗物质粒子湮灭的可能证据 : 天文信息 2008-11-20 : ...................

我也是 【 在 oo00oo (不是小蘑菇。。|她把号送我了。。) 的大作中提到: 】 : 好强大，看不懂的说

暗物质不是基本只受引力作用吗？为什么会这么大规模的湮灭呢。。。