Comparison of point source analysis methods in gamma ray astronomy (background estimation and source's bin size)

Abstract

A Monte Carlo program is written to compare several methods of analysis in the conventional right ascension scan, which are often used in searching for γ-ray point source in ultra high energy astronomy. The simulation is based on the zenith angle acceptance and the angular resolution of HEGRA array. Ten equatorial maps, each of more than 169,000 events, have been simulated. The excess-deficit distribution is found to be more compact when the background was extrapolated from region with the same acceptance as the source region. The results of the present study suggest that an off-source region should be at least six times greater than on-source window. The precision attained for a real signal from a point source is dependent on the source's bin size chosen. A window of 3°×3° or more would maximize the statistical significance of a signal for an angular resolution of ∼0.8°.