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Title: Gamma-ray bounds from EAS detectors and heavy decaying dark matter constraints

Abstract

The very high energy Galactic γ-ray sky is partially opaque in the (0.1–10) PeV energy range. In the light of the recently detected high energy neutrino flux by IceCube, a comparable very high energy γ-ray flux is expected in any scenario with a sizable Galactic contribution to the neutrino flux. Here we elaborate on the peculiar energy and anisotropy features imposed upon these very high energy γ-rays by the absorption on the cosmic microwave background photons and Galactic interstellar light. As a notable application of our considerations, we study the prospects of probing the PeV-scale decaying DM scenario, proposed as a possible source of IceCube neutrinos, by extensive air shower (EAS) cosmic ray experiments. In particular, we show that anisotropy measurements at EAS experiments are already sensitive to τ{sub DM}∼O(10{sup 27}) s and future measurements, using better gamma/hadron separation, can improve the limit significantly.

Authors:
 [1];  [2]
  1. INFN, Laboratori Nazionali del Gran Sasso,Assergi, AQ (Italy)
  2. LAPTh, Univ. de Savoie Mont Blanc, CNRS,B.P. 110, Annecy-le-Vieux, F-74941 (France)
Publication Date:
Sponsoring Org.:
SCOAP3, CERN, Geneva (Switzerland)
OSTI Identifier:
22458390
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2015; Journal Issue: 10; Other Information: PUBLISHER-ID: JCAP10(2015)014; OAI: oai:repo.scoap3.org:12157; Article funded by SCOAP3. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 License. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ABSORPTION; ANISOTROPY; DECAY; EXTENSIVE AIR SHOWERS; GAMMA RADIATION; HADRONS; LIMITING VALUES; NEUTRINOS; NONLUMINOUS MATTER; PEV RANGE; PHOTONS; RELICT RADIATION; VISIBLE RADIATION

Citation Formats

Esmaili, Arman, and Serpico, Pasquale Dario. Gamma-ray bounds from EAS detectors and heavy decaying dark matter constraints. United States: N. p., 2015. Web. doi:10.1088/1475-7516/2015/10/014.
Esmaili, Arman, & Serpico, Pasquale Dario. Gamma-ray bounds from EAS detectors and heavy decaying dark matter constraints. United States. doi:10.1088/1475-7516/2015/10/014.
Esmaili, Arman, and Serpico, Pasquale Dario. 2015. "Gamma-ray bounds from EAS detectors and heavy decaying dark matter constraints". United States. doi:10.1088/1475-7516/2015/10/014.
@article{osti_22458390,
title = {Gamma-ray bounds from EAS detectors and heavy decaying dark matter constraints},
author = {Esmaili, Arman and Serpico, Pasquale Dario},
abstractNote = {The very high energy Galactic γ-ray sky is partially opaque in the (0.1–10) PeV energy range. In the light of the recently detected high energy neutrino flux by IceCube, a comparable very high energy γ-ray flux is expected in any scenario with a sizable Galactic contribution to the neutrino flux. Here we elaborate on the peculiar energy and anisotropy features imposed upon these very high energy γ-rays by the absorption on the cosmic microwave background photons and Galactic interstellar light. As a notable application of our considerations, we study the prospects of probing the PeV-scale decaying DM scenario, proposed as a possible source of IceCube neutrinos, by extensive air shower (EAS) cosmic ray experiments. In particular, we show that anisotropy measurements at EAS experiments are already sensitive to τ{sub DM}∼O(10{sup 27}) s and future measurements, using better gamma/hadron separation, can improve the limit significantly.},
doi = {10.1088/1475-7516/2015/10/014},
journal = {Journal of Cosmology and Astroparticle Physics},
number = 10,
volume = 2015,
place = {United States},
year = 2015,
month =
}
  • The very high energy Galactic γ-ray sky is partially opaque in the (0.1–10) PeV energy range. In the light of the recently detected high energy neutrino flux by IceCube, a comparable very high energy γ-ray flux is expected in any scenario with a sizable Galactic contribution to the neutrino flux. Here we elaborate on the peculiar energy and anisotropy features imposed upon these very high energy γ-rays by the absorption on the cosmic microwave background photons and Galactic interstellar light. As a notable application of our considerations, we study the prospects of probing the PeV-scale decaying DM scenario, proposed asmore » a possible source of IceCube neutrinos, by extensive air shower (EAS) cosmic ray experiments. In particular, we show that anisotropy measurements at EAS experiments are already sensitive to τ{sub DM}∼ O(10{sup 27}) s and future measurements, using better gamma/hadron separation, can improve the limit significantly.« less
  • If dark matter is unstable and the mass is within GeV–TeV regime, its decays produce high-energy photons that give contribution to the extragalactic gamma-ray background (EGRB). We constrain dark matter decay by analyzing the 50-month EGRB data measured with Fermi satellite, for different decay channels motivated with several supersymmetric scenarios featuring R-parity violation. We adopt the latest astrophysical models for various source classes such as active galactic nuclei and star-forming galaxies, and take associated uncertainties properly into account. The lower limits for the lifetime are very stringent for a wide range of dark matter mass, excluding the lifetime shorter thanmore » 10{sup 28} s for mass between a few hundred GeV and ∼1 TeV, e.g., for b b-bar decay channel. Furthermore, most dark matter models that explain the anomalous positron excess are also excluded. These constraints are robust, being little dependent on astrophysical uncertainties, unlike other probes such as Galactic positrons or anti-protons.« less
  • While the excess in cosmic-ray electrons and positrons reported by PAMELA and Fermi may be explained by dark matter decaying primarily into charged leptons, this does not necessarily mean that dark matter should not have any hadronic decay modes. In order to quantify the allowed hadronic activities, we derive constraints on the decay rates of dark matter into WW, ZZ, hh, q q-bar and gg using the Fermi and HESS gamma-ray data. We also derive gamma-ray constraints on the leptonic e{sup +}e{sup −}, μ{sup +}μ{sup −} and τ{sup +}τ{sup −} final states. We find that dark matter must decay primarilymore » into μ{sup +}μ{sup −} or τ{sup +}τ{sup −} in order to simultaneously explain the reported excess and meet all gamma-ray constraints.« less
  • We analyze the impact of Fermi gamma-ray observations (primarily non-detections) of selected nearby galaxies, including dwarf spheroidals, and of clusters of galaxies on decaying dark matter models. We show that the fact that galaxy clusters do not shine in gamma rays puts the most stringent limits available to-date on the lifetime of dark matter particles for a wide range of particle masses and decay final states. In particular, our results put strong constraints on the possibility of ascribing to decaying dark matter both the increasing positron fraction reported by PAMELA and the high-energy feature in the electron-positron spectrum measured bymore » Fermi. Observations of nearby dwarf galaxies and of the Andromeda Galaxy (M31) do not provide as strong limits as those from galaxy clusters, while still improving on previous constraints in some cases.« less
  • Recently the PAMELA experiment has released its updated anti-proton flux and anti-proton to proton flux ratio data up to energies of ≈ 200GeV. With no clear excess of cosmic ray anti-protons at high energies, one can extend constraints on the production of anti-protons from dark matter. In this letter, we consider both the cases of dark matter annihilating and decaying into standard model particles that produce significant numbers of anti-protons. We provide two sets of constraints on the annihilation cross-sections/decay lifetimes. In the one set of constraints we ignore any source of anti-protons other than dark matter, which give themore » highest allowed cross-sections/inverse lifetimes. In the other set we include also anti-protons produced in collisions of cosmic rays with interstellar medium nuclei, getting tighter but more realistic constraints on the annihilation cross-sections/decay lifetimes.« less