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Date
2024
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Abstract
Eine Vielzahl von Gammastrahlungsquellen wurde milthilfe der aktuellen Genera-
tion von Imaging Atmospheric Cherenkov Telescopes (IACTs)-Experimenten gefunden.
Dennoch verbleiben fundamentale Fragen offen: Wie werden die Teilchen der kosmischen
Strahlung beschleunigt? Was können wir über die extremen Umgebungen nahe von schwar-
zen Löchern und Supernovae lernen? Wird die Dunkle Materie jemals gefunden werden?
Um diese Fragen zu beantworten, werden sowohl Experimente benötigt, die um ein
Vielfaches sensitiver als die derzeit verfügbaren sind, als auch neue Methoden der Daten-
analyse. Zu diesem Zweck wird derzeit ein neues Observatorium errichtet, das Cherenkov
Telescope Array Observatory (CTAO). Der erste Teleskopprototyp, das Large-Sized Te-
lescope Prototype (LST-1) auf La Palma wurde 2018 eingeweiht. Seitdem nimmt es als Teil
des Inbetriebnahmeprozesses Daten auf und bringt erste wissenschaftliche Erkenntnisse
hervor während die weiteren Teleskope errichtet werden.
In dieser Arbeit werden Daten aus Beobachtungen der Radioquelle M87 analysiert, die
von dem LST-1 zwischen April 2021 und Januar 2024 aufgenommen wurden. Dazu kommen
die low-level Software des LST-1, lstchain, und das CTAO Science Tool gammapy zum
Einsatz. Eine dreidimensionale Analyse wird entwickelt und Modelle für die Untergrund-
abschätzung erstellt. Diese zeigen, dass die Annahme radialer Symmetrie im Allgemeinen
nicht erfüllt ist und die Detektorantwort in einer allgemeineren Form beschrieben werden
sollte. Der gemessene Überschuss aus der Richtung von M87 ist nicht inkompatibel mit
der Untergrunderwartung, sodass eine Detektion der Quelle nicht möglich ist. Allerdings
ergibt eine Modellierung des Quellüberschusses Ergebnisse, die kompatibel zu früheren
Messungen von M87 während Phasen niedriger Aktivität sind.
Using the current-generation experiments of Imaging Atmospheric Cherenkov Tele- scopes (IACTs), a plethora of gamma-ray sources have been found in the sky. Nonetheless, there remain fundamental open questions in the field: How are cosmic rays accelerated? What can be learned about the extreme environments around black holes or supernovae? Will dark matter ever be found? Fully solving these questions will require experiments that are much more sensitive than currently available as well as more advanced methods of data analysis. To this end, a new observatory is currently under construction: the Cherenkov Telescope Array Observatory (CTAO). The first prototype telescope, the Large-Sized Telescope Prototype (LST-1) on La Palma was inaugurated in 2018. It is since taking data and producing the first scientific results as part of the commissioning while more telescopes of the CTAO are built. In this thesis, data from observations of the radio galaxy M87 taken with the LST-1 between April 2021 and January 2024 is analyzed using the low-level analysis pipeline for the LST-1, lstchain, and the CTAO science tool gammapy. A three-dimensional analysis is developed and performed, including the construction of three-dimensional background models. From the produced background models, it is apparent that the assumptions of radial symmetry are in general not fully met and more general forms need to be considered to describe the detector response. The measured excess from the position of M87 is not incompatible with the background expectation, so a detection of the source can not be claimed. However, modeling the measured excess, it is found to be consistent with previous measurents of the source during periods of low source activity.
Using the current-generation experiments of Imaging Atmospheric Cherenkov Tele- scopes (IACTs), a plethora of gamma-ray sources have been found in the sky. Nonetheless, there remain fundamental open questions in the field: How are cosmic rays accelerated? What can be learned about the extreme environments around black holes or supernovae? Will dark matter ever be found? Fully solving these questions will require experiments that are much more sensitive than currently available as well as more advanced methods of data analysis. To this end, a new observatory is currently under construction: the Cherenkov Telescope Array Observatory (CTAO). The first prototype telescope, the Large-Sized Telescope Prototype (LST-1) on La Palma was inaugurated in 2018. It is since taking data and producing the first scientific results as part of the commissioning while more telescopes of the CTAO are built. In this thesis, data from observations of the radio galaxy M87 taken with the LST-1 between April 2021 and January 2024 is analyzed using the low-level analysis pipeline for the LST-1, lstchain, and the CTAO science tool gammapy. A three-dimensional analysis is developed and performed, including the construction of three-dimensional background models. From the produced background models, it is apparent that the assumptions of radial symmetry are in general not fully met and more general forms need to be considered to describe the detector response. The measured excess from the position of M87 is not incompatible with the background expectation, so a detection of the source can not be claimed. However, modeling the measured excess, it is found to be consistent with previous measurents of the source during periods of low source activity.
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Keywords
Astronomie, LST, CTAO, Gamma-ray astronomy