Pulsars as the sources of high energy cosmic ray positrons

By D. Hooper, P. Blasi, P. Serpico. 2008

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Recent results from the PAMELA satellite indicate the presence of a large flux of positrons (relative to electrons) in the cosmic ray spectrum between approximately 10 and 100 GeV. As annihilating dark matter particles in many models are predicted to contribute to the cosmic ray positron spectrum in this energy range, a great deal of interest has resulted from this observation. Here, we consider pulsars (rapidly spinning, magnetized neutron stars) as an alternative source of this signal. After calculating the contribution to the cosmic ray positron and electron spectra from pulsars, we find that the spectrum observed by PAMELA could plausibly originate from such sources. In particular, a significant contribution is expected from the sum of all mature pulsars throughout the Milky Way, as well as from the most nearby mature pulsars (such as Geminga and B0656+14). The signal from nearby pulsars is expected to generate a small but significant dipole anisotropy in the cosmic ray electron spectrum, potentially providing a method by which the Fermi gamma-ray space telescope would be capable of discriminating between the pulsar and dark matter origins of the observed high energy positrons.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/81d67fe3df596490b6549db3d6a7c8dbf469c1c9

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Citations in the corpus

Dark matter direct detection signals inferred from a cosmological N-body simulation with baryons (2009, background): “The positron fraction rise observed by PAMELA [20], although striking, can be accommodated in standard astrophysical scenarios with pulsars [33, 34], or with an inhomogeneous distribution of supernovae remnants [35].”
The Dawn of FIMP Dark Matter: A Review of Models and Constraints (2017, background): “[125, 126]), DM annihilations can also be involved (see e.”
History of dark matter (2018, unknown): “…signal of annihilating dark matter, this possibility is now strongly constrained by a variety of arguments (Bertone et al., 2009; Galli et al., 2009; Slatyer, Padmanabhan, and Finkbeiner, 2009), and plausible astrophysical explanations have also been proposed (Hooper, Blasi, and Serpico, 2009).”
Dark Matter Candidates from Particle Physics and Methods of Detection (2010, result): “This exacerbates the PAMELA discrepancy, but the PAMELA data, with or without the modified spectral index, is consistent with expectations from pulsars derived both before (95; 96) and after (97; 98; 99) the PAMELA data (see Fig.”
Weak Corrections are Relevant for Dark Matter Indirect Detection (2010, background): “While the current excesses might be either due to a new astrophysical component, such as a nearby pulsar [7], or to some experimental problem, it could be produced by DM with a cross section a few orders of magnitude larger than in eq.”
Astrophysical models for the origin of the positron (2011, background): “[120, 121]), or a few prominent nearby sources, like Geminga or Monogem in [74, 77, 122, 117].”
Dark matter annihilations and decays after the AMS-02 positron measurements (2013, background): “by the interactions of high-energy photons in the strong magnetic fields of pulsars [38–42] (other possible sources of cosmic positrons are a nearby gamma-ray burst [43] or hadronic interactions inside the same sources that accelerate galactic cosmic rays [44]).”
Interpretation of AMS-02 electrons and positrons data (2014, background): “In this case, we will obtain that the prominent role of Geminga is reduced (its efficiency can now be smaller than in the previous case) but the additional “backgound” pulsars are constrained to possess relatively small efficiencies.”