TeV γ-ray observations of nearby Active Galactic Nuclei with the MAGIC telescope: exploring the high energy region of the multiwavelength picture Diego Tescaro | PhD Thesis | June 1, 2010 Supervised by Dr. Abelardo Moralejo Picture on the cover: The two MAGIC telescopes at the Observatory of Roque de los Muchachos in April 2009. Contents Introduction 1 1 Cosmic rays 3 1.1 Cosmic rays . 3 1.2 Cosmic ray composition . 3 1.3 Cosmic rays origin . 6 1.3.1 Cosmic rays acceleration . 7 1.3.2 Galactic CRs . 7 1.3.3 Extragalactic CRs . 8 1.4 The GZK-cutoff . 9 1.5 Cosmic rays anisotropy . 9 2 Gamma-ray astronomy 11 2.1 Gamma-ray astronomy . 11 2.2 Gamma-ray production . 12 2.2.1 The gamma-ray horizon . 14 2.3 Cosmic gamma-ray sources . 16 2.4 The case of RX J1713.7-3946 . 19 3 Active Galactic Nuclei 21 3.1 AGNs . 21 3.1.1 What exactly are we talking about? . 21 3.1.2 Classification . 24 3.1.3 Unified scheme . 24 3.2 Blazars . 26 3.2.1 The `blazar sequence' . 26 3.3 TeV emitters AGNs . 28 3.4 Emission models . 29 3.4.1 Spectral Energy Distribution (SED) . 30 3.4.2 Correlations . 30 3.4.3 Leptonic models . 31 3.4.4 Hadronic models . 32 3.5 AGNs as UHECR accelerators . 33 4 Detection of γ-rays 35 4.1 Detection of γ-rays . 35 4.1.1 Satellite-borne γ-ray detectors . 36 4.1.2 The Fermi γ-ray telescope . 38 i 4.2 Air showers . 39 4.2.1 The Cherenkov effect . 41 4.2.2 The light pool . 43 4.2.3 Fluorescence . 44 4.3 The Imaging Air Cherenkov Technique (IACT) . 44 4.3.1 Design and limits of a Cherenkov telescope . 46 4.3.2 Image formation . 47 4.3.3 Image parameters . 49 4.3.4 The time information . 51 4.3.5 Model analysis . 51 5 The MAGIC telescopes 53 5.1 MAGIC-I . 55 5.2 MAGIC-II . 56 5.3 MAGIC as a stereo system . 56 5.4 The telescopes components . 56 5.4.1 Frame . 57 5.4.2 Mirror . 58 5.4.3 Camera . 59 5.4.4 Readout electronics . 61 5.4.5 Trigger . 62 5.4.6 Digitization system . 62 5.4.7 Calibration . 63 5.4.8 Drive . 64 5.5 Performance of the stereo system . 65 5.5.1 Future plans . 65 6 Data analysis 67 6.1 Data analysis . 67 6.2 Analysis approaches . 67 6.3 Observation modes . 69 6.4 Montecarlo production . 70 6.5 Data quality . 72 6.6 The analysis pipeline . 73 6.6.1 Raw data reduction . 73 6.6.2 Calibration . 73 6.6.3 Image cleaning . 75 6.6.4 Image parameters calculation . 77 6.6.5 Background rejection . 81 6.6.6 The random forest . 83 6.6.7 Energy estimation . 85 6.6.8 Spectrum calculation . 86 6.6.9 Unfolding . 86 6.6.10 Lightcurve . 87 ii 7 Markarian 421 and Markarian 501 multiwavelength observations 89 7.1 Why multiwavelength campaigns? . 89 7.1.1 Motivations . 89 7.1.2 MWL coverage . 90 7.1.3 Mrk 421 . 92 7.1.4 Mrk 501 . 92 7.2 The MAGIC data and analysis . 93 7.2.1 The Random Forest training . 93 7.2.2 Montecarlo gamma sample . 94 7.2.3 Hadrons sample . 94 7.2.4 Gini-index . 95 7.2.5 Analysis threshold . 96 7.3 MAGIC results: Crab Nebula . 96 7.4 MAGIC results: Mrk 421 . 99 7.5 MAGIC results: Mrk 501 . 104 7.6 MWL handling tools . 107 7.7 Multiwavelength results . 108 7.8 Discussion . 111 7.8.1 The IC peak region . 111 7.8.2 The EBL correction . 112 7.8.3 The complete SED . 112 7.8.4 Modeling of the Mrk 421 SED . 113 7.8.5 Modeling of the Mrk 501 SED . 115 7.8.6 Conclusions . 116 8 Observations of Messier 87 during an intense flare activity 117 8.1 Motivations . 117 8.1.1 Messier 87 . 118 8.2 The MAGIC data and analysis . 119 8.2.1 Check of the analysis . 120 8.2.2 Moon data . 120 8.3 Results . 122 8.3.1 Preliminary results . 122 8.3.2 Results: Lightcurve . 124 8.3.3 Results: Spectrum . 125 8.3.4 Efficiency loss correction . 127 8.4 Discussion . 129 Summary and Conclusions 135 A Timing analysis 139 A.1 Introduction . 139 A.2 Analysis method . 140 A.2.1 Image Cleaning . ..