Localising the H.E.S.S. Galactic Centre point source

TL;DR

This paper refines the localization of the H.E.S.S. Galactic Centre gamma-ray source, reducing systematic errors and clarifying its association with Sgr A* rather than Sgr A East, based on improved observational data.

Contribution

It provides an updated, more precise position of the H.E.S.S. Galactic Centre source using advanced pointing corrections, excluding Sgr A East as the origin.

Findings

Systematic pointing error reduced to 6'' per axis.

Source position aligns with Sgr A* within errors.

Sgr A East is excluded as the gamma-ray source.

Abstract

Observations by the H.E.S.S. system of imaging atmospheric Cherenkov telescopes provide the most sensitive measurements of the Galactic Centre region in the energy range 150 GeV - 30 TeV. The vicinity of the kinetic centre of our galaxy harbours numerous objects which could potentially accelerate particles to very high energies (VHE, > 100 GeV) and thus produce the Gamma-ray flux observed. Within statistical and systematic errors, the centroid of the point-like emission measured by H.E.S.S. was found to be in good agreement with the position of the supermassive black hole Sgr A* and the recently discovered PWN candidate G359.95-0.04. Given a systematic pointing error of about 30'', a possible association with the SNR Sgr A East could not be ruled out with the 2004 H.E.S.S. data. In this contribution an update is given on the position of the H.E.S.S. Galactic Centre source using 2005/2006 data. The systematic pointing error is reduced to 6'' per axis using guiding telescopes for pointing corrections, making it possible to exclude with high significance Sgr A East as the source of the VHE Gamma-Rays.