The Eel Pulsar Wind Nebula: A PeVatron-candidate Origin for HAWC J1826−128 and HESS J1826−130

Daniel A. Burgess, Kaya Mori, Joseph D. Gelfand, Charles J. Hailey, Yarone M. Tokayer, Jooyun Woo, Hongjun An, Kelly Malone, Stephen P. Reynolds, Samar Safi-Harb, Tea Temim

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9 Scopus citations


HAWC J1826−128 is one of the brightest Galactic TeV γ-ray sources detected by the High Altitude Water Cherenkov (HAWC) observatory, with photon energies extending up to nearly ∼100 TeV. This HAWC source spatially coincides with the H.E.S.S. TeV source HESS J1826−130 and the “Eel” pulsar wind nebula (PWN), which is associated with the GeV pulsar PSR J1826−1256. In the X-ray band, Chandra and XMM-Newton revealed that the Eel PWN is composed of both a compact nebula (∼15″) and diffuse X-ray emission (∼6′ × 2′) extending away from the pulsar. Our NuSTAR observation detected hard X-ray emission from the compact PWN up to ∼20 keV and evidence of the synchrotron burn-off effect. In addition to the spatial coincidence between HESS J1826−130 and the diffuse X-ray PWN, our multiwavelength spectral energy distribution (SED) analysis using X-ray and γ-ray data establishes a leptonic origin of the TeV emission associated with the Eel PWN. Furthermore, our evolutionary PWN SED model suggests (1) a low PWN B-field of ∼1 μG, (2) a significantly younger pulsar age (t ∼ 5.7 kyr) than the characteristic age (τ = 14.4 kyr), and (3) a maximum electron energy of Emax = 2 PeV. The low B-field, as well as the putative supersonic motion of the pulsar, may account for the asymmetric morphology of the diffuse X-ray emission. Our results suggest that the Eel PWN may be a leptonic PeVatron particle accelerator powered by the ∼6 kyr old pulsar PSR J1826−1256 with a spin-down power of 3.6

Original languageEnglish (US)
Article numberac650a
JournalAstrophysical Journal
Issue number2
StatePublished - May 1 2022

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Gamma-ray astronomy (628)
  • Gamma-ray observatories (632)
  • Gamma-ray telescopes (634)
  • High energy astrophysics (739)
  • Pulsars (1306)
  • Rotation powered pulsars (1408)
  • Unified Astronomy Thesaurus concepts: X-ray astronomy (1810)
  • X-ray telescopes (1825)


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