Three-dimensional Search for Annihilating Dark Matter in CBe dSph with the MAGIC Telescopes

Abstract

Dark matter (DM) candidates, such as Weakly Interacting Massive Particles (WIMPs), can annihilate to Standard Model particles, subsequently producing gamma rays. In this work, we search for DM-induced gamma-ray signals from Coma Berenices dwarf spheroidal galaxy (CBe dSph) using approximately 25 hours of observations carried out by the Major Atmospheric Gamma Imaging Cherenkov (MAGIC) Telescope, located at Roque de los Muchachos Observatory, La Palma, Spain. Building upon preceding analyses in the gamma-ray regime, we extend the DM search into three dimensions by incorporating spatial information from the assumed DM-density distribution. This approach enhances sensitivity by leveraging both energy and spatial characteristics of the expected signal. The three-dimensional search for a faint signal necessitates the construction of a background model, leading to the proposal of the exclusion-rotation method. This method stacks all observations, excludes the source region, and corrects for the Azimuth-dependent acceptance of the telescopes by rotating the model. Furthermore, the open-source Python package TITRATE is presented, introducing Asimov datasets to the high-level analysis tool Gammapy for the approximation of the test statistic. No evidence of a DM-induced signal for annihilation to $b\bar{b}$, $W^+W^-$, $\mu^+\mu^-$, and $\tau^+\tau^-$ and DM masses $m_\chi$ between 0.17 TeV and 100 TeV in CBe dSph is found. Consequently, the first upper limits on the thermally averaged cross-section in energy and spatial dimensions using TITRATE are set, leading to a sensitivity improvement over previous results by MAGIC with respect to the assumed DM density in the target halo. The development of the Asimov method for DM search reduces the need for Monte Carlo simulations, paving the way for computationally efficient and scalable large-scale analyses across multiple targets and cosmic messengers.