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Abstract:
In order to investigate cosmic particle accelerators, like fast rotating neutron stars or supernova remnants, the very-high-energy (VHE: E > 100 GeV) γ-radiation
generated during these processes is detected by imaging atmospheric Cherenkov
telescopes (IACTs). With the H.E.S.S. telescopes, which are an array of four
such IACTs located in Namibia, many data sets have already been collected and
particularly the Galactic plane has been observed extensively. In the Galactic
Centre region, it has detected two strong point sources (G 0.9+0.1 and Sagittarius
A*) and an extended band of diffuse emission, located at the position of the giant
molecular cloud in the Galactic Centre.
In this work H.E.S.S. data from the Galactic Centre region is analyzed with an
event correlation method in order to find out if there are populations of weak
sources that cannot be detected individually by classical methods.
First, the event correlation method is compared to the ring background method
and then, it is verified in Monte Carlo simulations. For the generation of the required
null hypothesis maps different methods that randomize the data at small
scales are explained and analyzed. The findings of the simulations then tell how
strongly the data may be randomized without changing the large-scale distributions
and how many point sources and how many events per source there would
have to be in the data in order to get detected.
According to the correlation analysis, there are no small-scale anisotropies in the
event distribution, which means that the VHE γ-radiation from the Galactic Centre
region (minus the emission from Sagittarius A* and G 0.9+0.1) is consistent
with diffuse emission only.
