H.E.S.S data analysis of Gamma-ray binaries: HESS J0632+057 and LMC P3
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Date
2020
Authors
Moepi, Johannah
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Abstract
Context: Gamma-ray binaries consist of a normal star and a neutron star or
a black hole orbiting around the same centre of mass. This interaction produces
emission of gamma rays which dominates the electromagnetic spectrum. In this
research we take a close look at two gamma-ray binaries HESS J0632+057, located
near Rosette Nebula and the Monoceros Loop, and LMC P3, which is the first Extra-
Galactic gamma-ray binary located in the satellite galaxy of Milky Way, the Large
Magellanic Cloud. Cross-check analysis for H.E.S.S. observations for HESS J0632+057
is required and analysis of newly taken data for LMC P3 requires preparation, hence
the study of the two gamma-ray binaries.
Aim: In order to test that these two binary stars are gamma-ray emitters, periodic
emission signatures must be searched for and measured. Therefore the aim
of this research is to do a cross-check analysis of HESS J0632+057 using only new
and unpublished observations to obtain the average spectrum and do an analysis of
phase-folded light-curves to see if there is a periodic modulation. The second aim is
to prepare analysis of newly taken data of LMC P3.
Method: There have been observations of the sources in 2004-2012 and the data
have been taken by the H.E.S.S. telescopes. Analysis has been done using the standard
HESS Model++ software.
Results: There is a detection of the HESS J0632+057 with a statistical significance
of 8.6s. The light-curves were folded on the known period T0 = 54857.0 MJD and P0
= 316.2 days. The folded lightcurve shows a peak of emission in the orbital phase
range 0.6 to 0.9. Regarding LMC P3, analysis was not possible because there were
issues with instrument response functions. However, the noted errors can be a guide
for better analysis techniques. Conclusion: More data must be taken in order to have enough data points during
the periastron passage of HESS J0632+057. Analysis of LMC P3 has been prepared.
The analysis shows errors and the calibration of the data set needs to be
revisited. New instrument response functions must also be created to fix the error in
reading data of the CT5 telescope.
Description
A thesis submitted in fulfillment of the requirements for the degree of Master of Science in the School of Physics, Faculty of Science, University of the Witwatersrand, Johannesburg, 2020