2009/06/30 by Jie Liu, Qiang Yuan, Xiao-Jun Bi +3 · 1 citation
Physics and Astronomy · #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #Particle physics theoretical and experimental studies #astro-ph.CO
paper · pdf · doi:10.1103/physrevd.81.023516
10 pages, 6 figures, accepted for publication in PRD and calculations and discussions for the varying background of e^\pm added
openalex publication_date 2010/01/19 · arxiv created 2010/01/20 · arxiv updated 2010/02/08 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
In this paper we develop a Markov chain Monte Carlo code to study the dark matter properties in frameworks to interpret the recent observations of cosmic ray electron/positron excesses. We assume that the dark matter particles couple dominantly to leptons and consider two cases, annihilating or decaying into lepton pairs, respectively. The constraint on the central density profile from the H.E.S.S. observation of diffuse \ensuremathγ rays around the Galactic center is also included in the Markov chain Monte Carlo code self-consistently. In the numerical study, we have considered two cases of the background: fixed e+e^\ensuremath- background and the relaxed one. Two data sets of electrons/positrons, i.e. PAMELA+ATIC (Data set I) and PAMELA+Fermi\mathrm\text\ensuremath-LAT+H.E.S.S. (Data set II), are fitted independently, considering the current inconsistence between the observational data. We find that for Data set I, dark matter with m_\ensuremathχ\ensuremath≈0.70 TeV for annihilation (or 1.4 TeV for decay) and a non-negligible branching ratio to e+e^\ensuremath- channel is favored; while for Data set II, m_\ensuremathχ\ensuremath≈2.2 TeV for annihilation (or 4.5 TeV for decay) and the combination of \ensuremathμ+\ensuremathμ^\ensuremath- and \ensuremathτ+\ensuremathτ^\ensuremath- final states can best fit the data. We also show that the background of electrons and positrons actually will significantly affect the branching ratios. The H.E.S.S. observation of \ensuremathγ rays in the Galactic center ridge puts a strong constraint on the central density profile of the dark matter halo for the annihilation dark matter scenario. In this case the Navarro-Frenk-White profile, which is regarded as the typical predication from the cold dark matter scenario, is excluded with a high significance (>3\ensuremathσ). For the decaying dark matter scenario, the constraint is much weaker.