Fermi large area telescope search for photon lines from 30 to 200 GeV and dark matter implications

γ-ray Constraints on Decaying Dark Matter and Implications for IceCube

Utilizing the Fermi measurement of the γ-ray spectrum toward the Inner Galaxy, we derive some of the strongest constraints to date on the dark matter (DM) lifetime in the mass range from hundreds of MeV to above an EeV. Our profile-likelihood-based analysis relies on 413 weeks of Fermi Pass 8 data from 200 MeV to 2 TeV, along with up-to-date models for diffuse γ-ray emission within the Milky Way. We model Galactic and extragalactic DM decay and include contributions to the DM-induced γ-ray flux resulting from both primary emission and inverse-Compton scattering of primary electrons and positrons. For the extragalactic flux, we also calculate the spectrum associated with cascades of high-energy γ rays scattering off of the cosmic background radiation. We argue that a decaying DM interpretation for the 10 TeV-1 PeV neutrino flux observed by IceCube is disfavored by our constraints. Our results also challenge a decaying DM explanation of the AMS-02 positron flux. We interpret the results in terms of individual final states and in the context of simplified scenarios such as a hidden-sector glueball model.

The impact of recent advances in laboratory astrophysics on our understanding of the cosmos

An emerging theme in modern astrophysics is the connection between astronomical observations and the underlying physical phenomena that drive our cosmos. Both the mechanisms responsible for the observed astrophysical phenomena and the tools used to probe such phenomena-the radiation and particle spectra we observe-have their roots in atomic, molecular, condensed matter, plasma, nuclear and particle physics. Chemistry is implicitly included in both molecular and condensed matter physics. This connection is the theme of the present report, which provides a broad, though non-exhaustive, overview of progress in our understanding of the cosmos resulting from recent theoretical and experimental advances in what is commonly called laboratory astrophysics. This work, carried out by a diverse community of laboratory astrophysicists, is increasingly important as astrophysics transitions into an era of precise measurement and high fidelity modeling.

The moment of truth for WIMP dark matter

We know that dark matter constitutes 85 per cent of all the matter in the Universe, but we do not know of what it is made. Amongst the many dark matter candidates proposed, WIMPs (weakly interacting massive particles) occupy a special place, because they arise naturally from new theories that seek to extend the standard model of particle physics. With the advent of the Large Hadron Collider at CERN, and a new generation of astroparticle experiments, the moment of truth has come for WIMPs: either we will discover them in the next five to ten years, or we will witness their inevitable decline.