TY - JOUR
T1 - A Multiwavelength Interpretation of HESS J1857+026 Emission Using the Fermi-LAT, VERITAS, and HAWC Observatories
AU - The Fermi -LAT Collaboration
AU - The HAWC Collaboration
AU - The VERITAS Collaboration
AU - Eagle, J.
AU - Kumar, S.
AU - Archer, A.
AU - Bangale, P.
AU - Bartkoske, J. T.
AU - Benbow, W.
AU - Bond, N. R.
AU - Chen, Y.
AU - Christiansen, J. L.
AU - Chromey, A. J.
AU - Duerr, A.
AU - Errando, M.
AU - Escobar Godoy, M.
AU - Pedrosa, J. Escudero
AU - Feldman, S.
AU - Feng, Q.
AU - Filbert, S.
AU - Fortson, L.
AU - Furniss, A.
AU - Hanlon, W.
AU - Hinrichs, C. E.
AU - Holder, J.
AU - Humensky, T. B.
AU - Iskakova, M.
AU - Jin, W.
AU - Johnson, M. N.
AU - Joshi, E.
AU - Kaaret, P.
AU - Kertzman, M.
AU - Kherlakian, M.
AU - Kieda, D.
AU - Kleiner, T. K.
AU - Korzoun, N.
AU - Kumar, S.
AU - Kundu, S.
AU - Lundy, M.
AU - Maier, G.
AU - Millard, M. J.
AU - Moriarty, P.
AU - Mukherjee, R.
AU - Ong, R. A.
AU - Pandey, A.
AU - Pohl, M.
AU - Pueschel, E.
AU - Rabinowitz, P. L.
AU - Ragan, K.
AU - Reynolds, P. T.
AU - Roache, E.
AU - Sadeh, I.
AU - Saha, L.
N1 - Publisher Copyright:
© 2026. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
PY - 2026/7/10
Y1 - 2026/7/10
N2 - We present a new study on the MeV–TeV γ-ray origin of HESS J1857+026 using data collected from the Fermi–LAT, VERITAS, and HAWC observatories. A spatial and spectral study of HESS J1857+026 including radiative modeling of the MeV–TeV spectrum determines the likely dominant γ-ray origin as a pulsar wind nebula (PWN) powered by the energetic pulsar PSR J1856+0245. The MeV–TeV spectrum is further characterized through basic evolutionary radiative modeling assuming a PWN origin to constrain the physical properties of the system such as the magnetic field strength and PWN age. The results of the PWN evolutionary model are consistent with the observational constraints of the system, finding an age of the system between τ = [16, 21] kyr and a magnetic field strength between B = [0.4, 1.6] μG. These estimates support an evolved PWN scenario where the observed γ-ray emission is generated by the relativistic electrons' inverse Compton (IC) scattering off local photon fields; however, the low-energy (E < 10 GeV) spectral component could be dominated by hadronic emission originating from a supernova remnant (SNR). For a PWN component above 10 GeV, we measure the conditions for particle diffusion, finding that the local diffusion (D(50 TeV) ∼ 1028 cm−2 s−1) is suppressed compared to the interstellar medium (ISM) value, in agreement with similar TeV PWNe. By measuring the radial surface brightness profiles of the γ-ray source across multiple instruments, we demonstrate that the combined MeV–TeV spatial information is a powerful tool to constrain particle diffusion properties.
AB - We present a new study on the MeV–TeV γ-ray origin of HESS J1857+026 using data collected from the Fermi–LAT, VERITAS, and HAWC observatories. A spatial and spectral study of HESS J1857+026 including radiative modeling of the MeV–TeV spectrum determines the likely dominant γ-ray origin as a pulsar wind nebula (PWN) powered by the energetic pulsar PSR J1856+0245. The MeV–TeV spectrum is further characterized through basic evolutionary radiative modeling assuming a PWN origin to constrain the physical properties of the system such as the magnetic field strength and PWN age. The results of the PWN evolutionary model are consistent with the observational constraints of the system, finding an age of the system between τ = [16, 21] kyr and a magnetic field strength between B = [0.4, 1.6] μG. These estimates support an evolved PWN scenario where the observed γ-ray emission is generated by the relativistic electrons' inverse Compton (IC) scattering off local photon fields; however, the low-energy (E < 10 GeV) spectral component could be dominated by hadronic emission originating from a supernova remnant (SNR). For a PWN component above 10 GeV, we measure the conditions for particle diffusion, finding that the local diffusion (D(50 TeV) ∼ 1028 cm−2 s−1) is suppressed compared to the interstellar medium (ISM) value, in agreement with similar TeV PWNe. By measuring the radial surface brightness profiles of the γ-ray source across multiple instruments, we demonstrate that the combined MeV–TeV spatial information is a powerful tool to constrain particle diffusion properties.
KW - Diffuse radiation (383)
KW - Galactic cosmic rays (567)
KW - High energy astrophysics (739)
KW - Particle astrophysics (96)
KW - Pulsar wind nebulae (2215)
UR - https://www.scopus.com/pages/publications/105044324287
UR - https://www.scopus.com/pages/publications/105044324287#tab=citedBy
U2 - 10.3847/1538-4357/ae706f
DO - 10.3847/1538-4357/ae706f
M3 - Article
AN - SCOPUS:105044324287
SN - 0004-637X
VL - 1005
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 208
ER -