Constraining cosmic magnetic fields by a measurement of energy-energy-correlations with the Pierre Auger Observatory [Elektronische Ressource] / Peter Schiffer

Sujets

• Astronomie

Informations

• Publié par: rheinisch-westfalischen_technischen_hochschule_-rwth-_aachen
• Publié le: 01 janvier 2011
• Nombre de lectures: 6
• Langue: English
• Poids de l'ouvrage: 6 Mo

Extrait

Constraining Cosmic Magnetic Fields by
a Measurement of
Energy-Energy-Correlations with the
Pierre Auger Observatory
Von der Fakultat fur Mathematik, Informatik und Naturwissenschaften der RWTH¨ ¨
Aachen University zur Erlangung des akademischen Grades eines Doktors der
Naturwissenschaften genehmigte Dissertation
von
Dipl. Phys. Peter Schiffer
aus Reutlingen
Berichter: Universitatsprofessor Martin Erdmann¨
Universitatsprofessor Thomas Hebbeker¨
Tag der mu¨ndlichen Pru¨fung: 25.5.2011
Diese Dissertation ist auf den Internetseiten der Hochschulbibliothek online
verfu¨gbar.Contents
1 Introduction 1
2 Ultra High Energy Cosmic Rays 3
2.1 Cosmic Rays with Energies below 4 EeV . . . . . . . . . . . . . . . . 3
2.2 Sources of UHECRs. . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.3 Propagation of UHECRs . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3.1 Propagation in Background Photon Fields . . . . . . . . . . . 6
2.3.1.1 Energy Loss of Protons . . . . . . . . . . . . . . . . 7
2.3.1.2 Energy Loss of Nuclei . . . . . . . . . . . . . . . . . 8
2.3.2 Propagation in Cosmic Magnetic Fields . . . . . . . . . . . . . 9
2.4 Experimental Results on UHECRs . . . . . . . . . . . . . . . . . . . 12
2.4.1 Spectrum of UHECRs . . . . . . . . . . . . . . . . . . . . . . 13
2.4.2 Composition of UHECRs . . . . . . . . . . . . . . . . . . . . . 14
2.4.3 Photon Fraction of UHECRs . . . . . . . . . . . . . . . . . . . 15
2.4.4 Arrival Directions of UHECRs . . . . . . . . . . . . . . . . . . 16
3 Magnetic Fields in the Universe 19
3.1 Origin of Cosmic Magnetic Fields . . . . . . . . . . . . . . . . . . . . 19
3.2 Measurement of Cosmic Magnetic Fields . . . . . . . . . . . . . . . . 20
3.2.1 Zeeman Splitting . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.2.2 Starlight Polarization . . . . . . . . . . . . . . . . . . . . . . . 21
3.2.3 Faraday Rotation . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.2.4 Cosmic Microwave Background . . . . . . . . . . . . . . . . . 22
3.2.5 Cascades of TeV–Photons . . . . . . . . . . . . . . . . . . . . 23
3.3 Galactic Magnetic Field Models . . . . . . . . . . . . . . . . . . . . . 23
3.4 Extragalactic Magnetic Field Models . . . . . . . . . . . . . . . . . . 25ii Contents
4 Monte Carlo Model of UHECR Propagation 27
4.1 Propagation in Extragalactic Magnetic Fields . . . . . . . . . . . . . 27
4.2 Propagation in Galactic Magnetic Fields . . . . . . . . . . . . . . . . 29
4.3 Realization and Performance . . . . . . . . . . . . . . . . . . . . . . . 30
5 The Pierre Auger Observatory 33
5.1 Extensive Air Showers . . . . . . . . . . . . . . . . . . . . . . . . . . 33
5.2 The Surface Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
5.3 The Fluorescence Detector . . . . . . . . . . . . . . . . . . . . . . . . 36
5.4 Extensions of the Pierre Auger Observatory . . . . . . . . . . . . . . 38
5.4.1 The High Elevation Auger Telescope . . . . . . . . . . . . . . 38
5.4.2 The Auger Muons and Infill on the Ground Array . . . . . . . 39
5.4.3 The Auger Engineering Radio Array . . . . . . . . . . . . . . 39
5.4.4 The Northern Site of the Pierre Auger Observatory . . . . . . 39
5.5 Reconstruction of EAS with the Pierre Auger Observatory . . . . . . 40
5.5.1 Reconstruction with the Fluorescence Detector . . . . . . . . . 40
5.5.2 Reconstruction with the Surface Detector. . . . . . . . . . . . 42
6 Characterization of the Data Set 45
6.1 Data Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
6.2 Detector Acceptance . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
6.3 Angular Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
6.4 Energy Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
7 Energy-Energy-Correlations 51
7.1 Definition of Energy-Energy-Correlations . . . . . . . . . . . . . . . . 51
7.2 Energy Energy Correlation Method . . . . . . . . . . . . . . . . . . . 51
7.2.1 Jet Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
7.2.2 Energy-Energy-Correlation Distribution . . . . . . . . . . . . 52
7.2.3 Theoretical Expectation . . . . . . . . . . . . . . . . . . . . . 53
7.3 Error Propagation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
7.3.1 Statistical Uncertainties . . . . . . . . . . . . . . . . . . . . . 56
7.3.2 Systematic Uncertainties . . . . . . . . . . . . . . . . . . . . . 56
7.4 Measurement of Energy-Energy-Correlation Distribution . . . . . . . 57Contents iii
8 Interpretation of Measurement 59
8.1 Negative Log-Likelihood Method . . . . . . . . . . . . . . . . . . . . 59
8.2 Parameter Scan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
8.3 Interpretation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
9 Summary 65
A List of Abbreviations 67
B Additional Crosschecks of the EEC Method 69
B.1 Influence of Exposure Calculation . . . . . . . . . . . . . . . . . . . . 69
B.2 Reconstruction Quality of the EEC Method . . . . . . . . . . . . . . 70
C Validity of the MC Model 73
References 83
Acknowledgements 85iv ContentsList of Figures
2.1 Cosmic Ray Spectrum above 100 GeV . . . . . . . . . . . . . . . . . 4
2.2 Hillas Plot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3 Attenuation Length for Different Energy Loss Processes . . . . . . . . 8
2.4 Attenuation Length of Different Nuclei . . . . . . . . . . . . . . . . . 9
2.5 Propagation Distance of UHECRs . . . . . . . . . . . . . . . . . . . . 10
2.6 Particle Horizon for Protons . . . . . . . . . . . . . . . . . . . . . . . 11
2.7 Deflection of UHECRs in Spiral Magnetic Field Models . . . . . . . . 12
2.8 Deflection of UHECRs in the EGMF . . . . . . . . . . . . . . . . . . 12
2.9 Spectrum measured by HiRes . . . . . . . . . . . . . . . . . . . . . . 13
2.10 Spectrum measured by the Pierre Auger Observatory . . . . . . . . . 14
2.11 Composition measured by the Pierre Auger Observatory . . . . . . . 15
2.12 Composition measured by HiRes. . . . . . . . . . . . . . . . . . . . . 15
2.13 Photon fration measured by the Pierre Auger Observatory . . . . . . 16
2.14 AGN correlation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.1 Compilation of Starlight Polarization Measurements . . . . . . . . . . 21
3.2 Schematic View of the Faraday Effect . . . . . . . . . . . . . . . . . . 22
3.3 Spiral Magnetic Field Models . . . . . . . . . . . . . . . . . . . . . . 24
3.4 Extragalactic Magnetic Fields . . . . . . . . . . . . . . . . . . . . . . 26
4.1 Probability Maps Calculated with PARSEC . . . . . . . . . . . . . . 29
4.2 PARSEC Simulation Chain . . . . . . . . . . . . . . . . . . . . . . . 30
5.1 Detectors of the Pierre Auger Observatory . . . . . . . . . . . . . . . 34
5.2 Map of the Pierre Auger Observatory . . . . . . . . . . . . . . . . . . 34
5.3 Evolution of an Extensive Air Shower . . . . . . . . . . . . . . . . . . 35
5.4 Schematic View of a SD Station . . . . . . . . . . . . . . . . . . . . . 37vi List of Figures
5.5 Fluorescence Detector . . . . . . . . . . . . . . . . . . . . . . . . . . 37
5.6 Low Energy Extensions of the Pierre Auger Observatory . . . . . . . 38
5.7 Radio Detector Station of AERA . . . . . . . . . . . . . . . . . . . . 40
5.8 Layout for the Northern Site of the Pierre Auger Observatory . . . . 41
5.9 EAS measured by the Pierre Auger Observatory . . . . . . . . . . . . 41
5.10 Exemplary FD Event . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
5.11 Exemplary SD Event . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
5.12 Calibration Curve for the SD . . . . . . . . . . . . . . . . . . . . . . 44
6.1 Arrival Direction of the UHECRs in the Data Set . . . . . . . . . . . 46
6.2 Relative aperture of the SD . . . . . . . . . . . . . . . . . . . . . . . 46
6.3 Angular resolution of the SD . . . . . . . . . . . . . . . . . . . . . . . 48
6.4 Energy resolution of the SD . . . . . . . . . . . . . . . . . . . . . . . 49
7.1 Region of interest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
7.2 Arrival directions of UHECRs covered by a region of interest.. . . . . 53
7.3 Energy-Energy-Correlation distribution . . . . . . . . . . . . . . . . . 54
7.4 Expectation value of the EEC . . . . . . . . . . . . . . . . . . . . . . 55
7.5 EEC distribution for different number of events . . . . . . . . . . . . 55
7.6 Statistical variation of EEC distribution . . . . . . . . . . . . . . . . 56
7.7 Systematical variation of EEC distribution . . . . . . . . . . . . . . . 57
7.8 Measurement of the EEC distribution . . . . . . . . . . . . . . . . . . 58
8.1 Measurement of the EEC distribution . . . . . . . . . . . . . . . . . . 59
8.2 EEC distribution in the first bin . . . . . . . . . . . . . . . . . . . . . 61
8.3 Exclusion limits from a parameter scan of the UHECR model de-
scribed in the text. The strength of the turbulent magnetic field and
the source density were scanned. Dark blue denotes the allowed re-
gionoftheparameterspace(95%confidencelevel). Theblacklinesat
the transitions of the different shades of blue denote exclusion levels
(95%, 99.9% and 99.9996%) . . . . . . . . . . . . . . . . . . . . . . . 63
B.1 Effect of Geometric Exposure Calculation. . . . . . . . . . . . . . . . 69
B.2 Parameter Reconstruction Using the EEC Method . . .