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

HAWC J1826-128 is one of the brightest Galactic TeV gamma-ray sources detected by the High Altitude Water Cherenkov (HAWC) observatory, with photon energies extending up to nearly similar to 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 (similar to 15 '') and diffuse X-ray emission (similar to 6' x 2') extending away from the pulsar. Our NuSTAR observation detected hard X-ray emission from the compact PWN up to similar to 20 keV and evidence of the synchrotron burn-off effect. In addition to the spatial coincidence between HESS J1826-130 and the diffuse gamma-ray PWN, our multiwavelength spectral energy distribution (SED) analysis using X-ray and gamma-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 similar to 1 mu G, (2) a significantly younger pulsar age (t similar to 5.7 kyr) than the characteristic age (tau = 14.4 kyr), and (3) a maximum electron energy of E-max = 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 similar to 6 kyr old pulsar PSR J1826-1256 with a spin-down power of 3.6 x 10(36) erg s(-1).