Indirect dark matter searches on the Triangulum-II dwarf spheroidal galaxy and the Perseus galaxy cluster with the MAGIC telescopes
School
Universitat Autònoma de Barcelona - Institut de Física d'Altes Energies
Edifici Cn, Universitat Autònoma de Barcelona (UAB), E-08193 Bellaterra (Barcelona), Spain
External url: https://www.tdx.cat/handle/10803/462764
Abstract:
Decades of observational evidences have been accumulated to show that Standard Model (SM) particles cannot totally explain the strong unbalance between the measured matter and the gravitational potential observed in several astronomical regions, at all cosmological scales, from that of Milky Way satellite galaxies, to that of clusters of galaxies. Although some theories argue for the modification of the gravitational laws, the existence of a new massive particle (or a set of them), interacting only weakly with SM particles, provides a preferred explanation. It is estimated that this form of Dark Matter (DM) roughly accounts for 4 times the amount of SM matter, therefore shaping the evolution of cosmic structures along the history of the Universe. A well-motivated general framework for DM is that of a Weakly Interacting Massive Particle (WIMP), generic massive particles with a mass range expected between few GeVs and few hundreds TeV, interaction strengths at the weak scale, and either stable or very long lived. The WIMP paradigm has been long debated, and has the advantage of being at reach by different of the top-class instruments of the current times, so that a putative discovery could be validated independently. I focus on the indirect search of DM, where annihilating or decaying WIMP are expected to emit gamma rays at energies detectable by Imaging Atmospheric Cherenkov Telescopes (IACTs), as the currently operating Florian Goeble Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) telescopes or the future Cherenkov Telescope Array (CTA). The expected DM signal can be moderately extended when compared to IACT field of view, what challenges the performance of the DM search of these instruments. In this thesis, I contribute to the MAGIC scientific general research and, in particular, to the ongoing efforts on indirect DM searches, at different analysis levels. I develop a tool for handling the massive data products generated by current high energy experiments. Moreover, a tailored Monte Carlo (MC) for moderate extended sources is proposed as an upgrade of the current general MC for extended sources. Finally, a method to optimize the pointing strategy of IACT while observing moderately extended sources, taking into account the off-axis performance of the instrument, has also been developed and, implemented for the first time to indirect DM searches on highly DM dominated nearby dwarf Spheroidal galaxy. I also show my contribution to the largest telescope to be part of CTA, the Large Sized Telescope, that will dominate the CTA sensitivity for standard WIMP searches. Constraints on the WIMP thermally averaged cross-section and/or decay life-time are put with 60 hours of data in the recently discovered dwarf Spheroidal galaxy Tri- angulum II and 202 hours on the Perseus cluster. On both searches, I apply a binned maximum-likelihood analysis optimized for exploiting the spectral and morphological features of gamma-ray signals of DM from annihilating or decaying WIMP. Consid- ering astrophysical factors of J ann (< 0.5 ◦ ) = 10 21 GeV 2 cm −5 for Triangulum II and J dec (< 2 ◦ ) = 1.5 × 10 19 GeV cm −2 for the Perseus cluster, we reach sensitivities to the thermally averaged cross-section of 0.3 × 10 −24 cm 3 s −1 and decay life-times of 10 26 s respectively.
Keywords:
Dark Matter, IACT, MAGIC, CTA, extended source analisys