Astroparticle Physics

16 1 Historical IntroductionW + ,W − ,ZFig. 1.16Supernova explosion SN 1987A inthe Tarantula Nebula {6}ROSATHubble telescopeCGROthe bosons of the weak interaction (W + ,W − ,Z;CERN 131983; Nobel Prize for Rubbia and van der Meer 1984). Thediscovery of asymptotic freedom of quarks in the theory ofthe strong interaction by Gross, Politzer, and Wilczek washonored by the Nobel Prize in 2004.The observation of the supernova explosion 1987A,along with the burst of extragalactic neutrinos, representedthe birth of real astroparticle physics. The measurement ofonly 20 neutrinos out of a possible 10 58 emitted, allowedelementary particle physics investigations that were hithertoinaccessible in laboratory experiments. The dispersion ofarrival times enabled physicists to derive an upper limit ofthe neutrino mass (m νe < 10 eV). The mere fact that theneutrino source was 170 000 light-years away in the LargeMagellanic Cloud, allowed a lower limit on the neutrinolifetime to be estimated. The gamma line emission from SN1987A gave confirmation that heavy elements up to iron,cobalt, and nickel were synthesized in the explosion, inagreement with predictions of supernova models. As the firstoptically visible supernova since the discovery of the telescope,SN 1987A marked an ideal symbiosis of astronomy,astrophysics, and elementary particle physics (Fig. 1.16).The successful launch of the high-resolution X-ray satelliteROSAT 14 in 1990, paved the way for the discovery ofnumerous X-ray sources. The Hubble telescope, which wasstarted in the same year, provided optical images of stars andgalaxies in hitherto unprecedented quality, once the slightlydefocusing mirror had been adjusted by a spectacular repairin space. The successful mission of ROSAT was followedby the X-ray satellites Chandra (named after SubrahmanyanChandrasekhar, Nobel Prize 1983) and XMM 15both launched in 1999.The Compton Gamma-Ray Observatory (CGRO,launched in 1991) opened the door for GeV gammaastronomy. Ground-based atmospheric air Cherenkov telescopesand extensive air-shower experiments were able toidentify TeV point sources in our Milky Way (Crab Nebula,12 DESY – Deutsches Elektronen Synchrotron in Hamburg13 CERN – Conseil Européen pour la Recherche Nucléaire14 ROSAT – ROentgen SATellite of the Max-Planck Institute forExtraterrestrial Physics, Munich15 XMM – X-ray Multi-Mirror mission, renamed Newton Observatoryin 2002