Focusing Telescopes in Nuclear Astrophysics

HESS (High Energy Stereoscopic System), a ground-based Cerenkov array telescopes has been operated since a few years and in 2004 has performed the ?rst Galactic plane scan with a sensitivity of a few percent of the Crab at energies above 100 GeV, resulting in the discoveryofeightsources,mostofwhichwithoutanycounterpartatdifferentenergies[1,2]. ParticularattentionwasdevotedtoHESSJ1813-178,notidenti?edwithanyknownX/gamma ray emitter and hypothesised to be a dark particle accelerator. Independently, and at the same time, INTEGRAL discovered a new soft gamma-ray source, namely IGR J18135-1751, identi?edasthecounterpartofHESSJ1813-178.Thishighenergyemitter,whosenaturewas still mysterious at the time of the discovery was then associated with the supernova remnant (SNR) G12.82 0.02 [6, 10, 18]. Even if a chance coincidence cannot be completely ruled out in view of the 2 arcmin INTEGRAL error box and the possible angular extension in the high energy,theoverallcharacteristicsofthisstarformingregion[7]comprisingSNRG12.82 0.02 areconsistentwithsupernova/plerionorigin.Morerecently,theMAGIC(MajorAtmospheric Gamma Imaging Cerenkov telescope) collaboration has reported a positive observations of HESSJ1813–178;resultinginagamma-ray?uxconsistentwiththepreviousHESSdetection and showing a hard power law with? = 2.1 in the range from 0.4–10TeV [3].