A Markov Chain Monte Carlo Study on Dark Matter Property Related to the Cosmic e${}^{\pm }$ Excesses

Abstract

In this paper we develop a Markov Chain Monte Carlo code to study the dark matter properties in interpreting the recent observations of cosmic ray electron/positron excesses. We assume that the dark matter particles couple dominantly to leptons and consider two cases separately with annihilating or decaying into lepton pairs. The constraint on the central density profile from diffuse $\gamma$-rays around the Galactic center is also included in the Markov Chain Monte Carlo code self-consistently. In the numerical study, 7 parameters are introduced. We fit two data sets independently and find that for the Data set I (PAMELA+ATIC), dark matter with $m_{\chi }\approx 0.7$ TeV for annihilation (or 1.4 TeV for decay) and pure $e^{+}{e}^{-}$ channel is favored, while for the Data set II (PAMELA+Fermi-LAT+H.E.S.S.) $m_{\chi }\approx 2$ TeV for annihilation (or 4 TeV for decay) and the combination of ${\mu }^{+}{\mu }^{-}$ and ${\tau }^{+}{\tau }^{-}$ final states can best fit the data. The H.E.S.S. observation of the Galactic center $\gamma$-rays puts a strong constraint on the central density profile of the dark matter halo for the annihilation dark matter scenario. In this case the NFW profile which is regarded as the typical predication from the cold dark matter scenario, is excluded with a high significance ($>5\sigma$). For the decaying dark matter scenario, the constraint is much weaker.

10 pages, 6 figures, accepted for publication in PRD and calculations and discussions for the varying background of e^\pm added

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• Implications of the AMS-02 positron fraction in cosmic rays
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• CosRayMC: a global fitting method in studying the properties of the new sources of cosmic e${}^{\pm }$ excesses
• Leptonic dark matter annihilation in the evolving universe: constraints and implications
• Implications on cosmic ray injection and propagation parameters from Voyager/ACE/AMS-02 nucleus data
• Secondary cosmic-ray nucleus spectra disfavor particle transport in the Galaxy without reacceleration
• Gamma rays and neutrinos from dark matter annihilation in galaxy clusters
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• Galactic cosmic-ray model in the light of AMS-02 nuclei data
• Bayesian analysis of the break in DAMPE lepton spectra
• Systematic study of the uncertainties in fitting the cosmic positron data by AMS-02
• Search for dark matter signals with Fermi-LAT observation of globular clusters NGC 6388 and M 15
• Breit-Wigner Enhancement Considering the Dark Matter Kinetic Decoupling
• Constraining the Milky Way Dark Matter Density Profile with Gamma-Rays with Fermi-LAT
• Decaying Dark Matter in the Supersymmetric Standard Model with Freeze-in and Seesaw mechanims
• Cosmic e^\pm, \bar p, γand neutrino rays in leptocentric dark matter models