3D Analysis of MAGIC Boomerang Supernova Remnant Data Using Standardized Data Formats and Open-Source Analysis Tools
School
Ludwigs-Maximilians-Universität München
Abstract:
In this thesis, I analyzed archival MAGIC data of the Boomerang Supernova Remnant (SNR) PeVatron candidate, G106.3+2.7, with a novel 3D analysis method using standardized data formats and open-source analysis tools. The source has a complex comet-shaped structure and is commonly divided into a Head and Tail region, where the Head region is associated to the pulsar PSR J2229+6114 and its Pulsar Wind Nebula (PWN) G106.6+2.9. The 3D analysis technique is the most suitable method for extended-source analyses and more precise than the approach that was previously chosen for a published study by the MAGIC collaboration [76]. In the latter, G106.3+2.7 is found to exhibit a clear energy-dependent morphology, with a multi-TeV signal from the Tail region and indications for a related hadronic emission mechanism. First, I re-analyzed the dataset with the standard analysis software of MAGIC, the MARS, confirming the results from the paper. Then, I set up a 3D analysis pipeline including the computation of dedicated Instrument Response Functions (IRFs), the generation of background models with the open-source package pybkgmodel and the data reduction and modeling and fitting routines with gammapy. The pipeline was tested on the well-characterized Crab Nebula. This enabled the identification of two distinct systematic effects: an asymmetric feature in the background significance histogram at low energies and a systematic shift of the mean in the significance histograms of the background. The former of these could be reduced as a consequence. The reasonable spectral results I obtained validated the pipeline for usage on other sources. I find a Gaussian spatial model to be more probable than a point-like model for the description of the Crab Nebula. I provide the most stringent Upper Limit (UL) for extended emission of the Crab Nebula ever measured by the MAGIC telescopes, with a value of σ = (0.0239 ±0.0008) sigma. It is not only compatible with previous measurements by the Fermi-LAT and H.E.S.S. experiments, but of the same order of magnitude, suggesting that it is on the verge of a detection. Finally, I report on the application of the 3D analysis pipeline to Boomerang SNR data. The morphological results obtained for G106.3+2.7 in this thesis are predominantly confirming the findings of the previous publication, with a new hint at multi-TeV emission from the Head region. The spectral results of the 3D double symmetric Gaussian fits indicate a slightly harder index for the Head region than the 1D analysis of this work and the published work, while the indices for the Tail region are all very consistent. Furthermore, all spectral results are also in agreement with the related publication by MAGIC inside uncertainty intervals. A comparison of the quality of different spatial models indicates that the emission can reasonably be explained with two distinct symmetric Gaussian emission regions, the Head and the Tail region, or with a single asymmetric Gaussian region. The most important uncertainty in this analysis is introduced by the background estimation and modeling, and it is discussed in detail. This work demonstrates that the novel 3D analysis technique is developing into a powerful tool for the analysis of γ-ray data in several ways. With dedicated 3D background models, it enables to perform the analysis of complex emission regions with simultaneous spatial and spectral fitting and possibly to detect the extension of nearly point-like sources below the angular resolution limit of an instrument. Concluding, I offer several promising prospects of future research along the lines of work treated in this thesis.