Observations of the Sagitarrius dwarf galaxy by the HESS experiment and search for a dark matter signal

Abstract

Observations of the Sagittarius dwarf spheroidal (Sgr dSph) galaxy were carried out with the HESS array of four imaging air Cherenkov telescopes in June 2006. A total of 11 h of high quality data are available after data selection. There is no evidence for a very high energy γ-ray signal above the energy threshold at the target position. A 95% CL flux limit of View the MathML source3.6×10-12cm-2s-1 above 250 GeV has been derived. Constraints on the velocity-weighted cross-section 〈σv〉〈σv〉 are calculated in the framework of dark matter particle annihilation using realistic models for the dark matter halo profile of Sagittarius dwarf galaxy. Two different models have been investigated encompassing a large class of halo types. A 95% CL exclusion limit on 〈σv〉〈σv〉 of the order of View the MathML source2×10-25cm3s-1 is obtained for a core profile in the 100 GeV–1 TeV neutralino mass range