Data analysis of Markarian 421 observed by the high energy stereoscopic system (H.E.S.S.) in January 2017
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Date
2021
Journal Title
Journal ISSN
Volume Title
Publisher
University of Namibia
Abstract
The investigation of Active Galactic Nuclei (AGN) is one of the most important areas
of contemporary astrophysics. In general, the term AGN refers to the existence of
energetic phenomena in the nucleus (central region) of a galaxy which cannot be
attributed to the stars in that galaxy. Blazars are AGN that are viewed from Earth head on, and that exhibits extra-ordinary large variability on time scales sometimes less than
hours, often displaying highly irregular and flare-like behavior. Among blazars
detected at very-high energies, Markarian 421 is one of the brightest and best studied.
It was detected by the High Energy Stereoscopic System (H.E.S.S.) in January 2017
during a flaring state. H.E.S.S. is a y-ray astronomy array of telescopes, located in
Namibia, near the Gamsberg mountain, an area known for its excellent astronomical
observational conditions.
The observational data from the H.E.S.S. experiment was used in this case to obtain
and explain the light curve and the energy spectrum for the seven data sets recorded in
January 2017. With the Model++ (also called Paris Analysis) standard cuts analysis,
an excess of 115.5 y rays, for Nan = 122 on-source and Naff = 108 off-source events
are detected at the 19.9cr significance level. We have observed that the energy
spectrum, can be well described by a power-law with spectral index 3.22± 0.27
decreasing in flux as the energy increases. Fitting the observed Spectral Energy
Distribution (SED) with a power-law with exponential cut-off is observed to have the
spectral index 0.80 ± 1.61 with the exponential cut at 2.53 ± 1.70 TeV photon
energy.
As for the light curves (the radiation flux as a function oftime), the scarcity ofthe data
could not reveal any meaningful variability pattern to be deduced from these January
2017 observations
Description
A thesis submitted in partial fulfilment of the requirements for the Degree of Master of Science in Physics
Keywords
Astrophysics, Active Galactic Nuclei (AGN), Time scales, Data analysis, Markarian 421, High energy stereoscopic system (H.E.S.S.), Namibia, University of Namibia