skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Dark cosmic rays

Abstract

If dark matter particles have an electric charge, as in models of millicharged dark matter, such particles should be accelerated in the same astrophysical accelerators that produce ordinary cosmic rays, and their spectra should have a predictable rigidity dependence. Depending on the charge, the resulting “dark cosmic rays” can be detected as muon-like or neutrino-like events in Super-Kamiokande, IceCube, and other detectors. We present new limits and propose several new analyses, in particular, for the Super-Kamiokande experiment, which can probe a previously unexplored portion of the millicharged dark matter parameter space. Here, most of our results are fairly general and apply to a broad class of dark matter models.

Authors:
 [1];  [2];  [3]
  1. Univ. of California, Los Angeles, CA (United States). Dept. of Physics and Astronomy
  2. Univ. of California, Los Angeles, CA (United States). Dept. of Physics and Astronomy; Univ. of Tokyo (Japan). Kavli Inst. for the Physics and Mathematics of the Universe (WPI)
  3. Univ. of California, Los Angeles, CA (United States). Dept. of Physics and Astronomy; Univ. of California, Irvine, CA (United States). Dept. of Physics and Astronomy
Publication Date:
Research Org.:
Univ. of California, Los Angeles, CA (United States); Univ. of California, Irvine, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1344430
Alternate Identifier(s):
OSTI ID: 1368174
Grant/Contract Number:
SC0009937; SC0009920; PHY-1066293
Resource Type:
Journal Article: Published Article
Journal Name:
Physics Letters. Section B
Additional Journal Information:
Journal Volume: 768; Journal Issue: C; Journal ID: ISSN 0370-2693
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

Citation Formats

Hu, Ping-Kai, Kusenko, Alexander, and Takhistov, Volodymyr. Dark cosmic rays. United States: N. p., 2017. Web. doi:10.1016/j.physletb.2017.02.035.
Hu, Ping-Kai, Kusenko, Alexander, & Takhistov, Volodymyr. Dark cosmic rays. United States. doi:10.1016/j.physletb.2017.02.035.
Hu, Ping-Kai, Kusenko, Alexander, and Takhistov, Volodymyr. Wed . "Dark cosmic rays". United States. doi:10.1016/j.physletb.2017.02.035.
@article{osti_1344430,
title = {Dark cosmic rays},
author = {Hu, Ping-Kai and Kusenko, Alexander and Takhistov, Volodymyr},
abstractNote = {If dark matter particles have an electric charge, as in models of millicharged dark matter, such particles should be accelerated in the same astrophysical accelerators that produce ordinary cosmic rays, and their spectra should have a predictable rigidity dependence. Depending on the charge, the resulting “dark cosmic rays” can be detected as muon-like or neutrino-like events in Super-Kamiokande, IceCube, and other detectors. We present new limits and propose several new analyses, in particular, for the Super-Kamiokande experiment, which can probe a previously unexplored portion of the millicharged dark matter parameter space. Here, most of our results are fairly general and apply to a broad class of dark matter models.},
doi = {10.1016/j.physletb.2017.02.035},
journal = {Physics Letters. Section B},
number = C,
volume = 768,
place = {United States},
year = {Wed Feb 22 00:00:00 EST 2017},
month = {Wed Feb 22 00:00:00 EST 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1016/j.physletb.2017.02.035

Save / Share:
  • Gravitational lensing observations of galaxy clusters have identified dark matter blobs with remarkably low baryonic content. We use such a blob to probe the particle nature of dark matter with x-ray observations. From these observations we improve the most conservative constraints from the Milky Way halo on a particular dark matter candidate, the sterile neutrino, by an order of magnitude. We also study high resolution x-ray grating spectra of a cluster of galaxies. Based on these conservative constraints obtained from cosmic x-ray observations alone, the low mass (m{sub s} < or approx.10 keV) and low mixing angle (sin{sup 2}(2{theta}) <more » or approx. 10{sup -6}) sterile neutrino is still a viable dark matter candidate.« less
  • In models with extra dimensions the fundamental scale of gravity M{sub D} could be of the order of TeV. In that case the interaction cross section between a cosmic proton of energy E and a dark matter particle {chi} will grow fast with E for center-of-mass energies {radical}(2m{sub {chi}}E) above M{sub D}, and it could reach 1 mbarn at E Almost-Equal-To 10{sup 9} GeV. We show that these gravity-mediated processes would break the proton and produce a diffuse flux of particles/antiparticles, while boosting {chi} with a fraction of the initial proton energy. We find that the expected cross sections andmore » dark matter densities are not enough to produce an observable asymmetry in the flux of the most energetic (extragalactic) cosmic rays. However, we propose that unsuppressed TeV interactions may be the origin of the knee observed in the spectrum of galactic cosmic rays. The knee would appear at the energy threshold for the interaction of dark matter particles with cosmic protons trapped in the galaxy by Micro-Sign G magnetic fields, and it would imply a well-defined flux of secondary antiparticles and TeV gamma rays.« less
  • Clusters of galaxies have not yet been detected at gamma-ray frequencies; however, the recently launched Fermi Gamma-ray Space Telescope, formerly known as GLAST, could provide the first detections in the near future. Clusters are expected to emit gamma rays as a result of (1) a population of high-energy cosmic rays fueled by accretion, merger shocks, active galactic nuclei, and supernovae, and (2) particle dark-matter annihilation. In this paper, we ask the question of whether the Fermi telescope will be able to discriminate between the two emission processes. We present data-driven predictions for the gamma-ray emission from cosmic rays and darkmore » matter for a large x-ray-flux-limited sample of galaxy clusters and groups. We point out that the gamma-ray signals from cosmic rays and dark matter can be comparable. In particular, we find that poor clusters and groups are the systems predicted to have the highest dark-matter to cosmic-ray emission ratio at gamma-ray energies. Based on detailed Fermi simulations, we study observational handles that might enable us to distinguish the two emission mechanisms, including the gamma-ray spectra, the spatial distribution of the signal, and the associated multiwavelength emissions. We also propose optimal hardness ratios, which will help us to understand the nature of the gamma-ray emission. Our study indicates that gamma rays from dark-matter annihilation with a high particle mass can be distinguished from a cosmic-ray spectrum even for fairly faint sources. Discriminating a cosmic-ray spectrum from a light dark-matter particle will be, instead, much more difficult, and will require long observations and/or a bright source. While the gamma-ray emission from our simulated clusters is extended, determining the spatial distribution with Fermi will be a challenging task requiring an optimal control of the backgrounds.« less
  • Extremely high energy ({approximately}10{sup 22} eV ) cosmic neutrino beams initiate high energy particle cascades in the background of relic neutrinos from the big bang. We perform numerical calculations to show that such cascades could contribute more than 10{percent} to the observed cosmic ray flux above 3{times}10{sup 19} eV if neutrinos have {approximately}eV masses. The required intensity of primary neutrinos could be consistent with astrophysical models for their production {ital if} the maximum neutrino energy reaches to {approximately}10{sup 22} eV {ital and} the massive neutrino dark matter is locally clustered. Future observations of ultrahigh energy cosmic rays will lead tomore » an indirect but practical search for neutrino dark matter. {copyright} {ital 1998} {ital The American Physical Society}« less