Document Type
Article
Publication Date
9-20-2024
Department
Department of Physics
Abstract
We report an observation of ultrahigh-energy (UHE) gamma rays from the Galactic center (GC) region, using 7 yr of data collected by the High-Altitude Water Cherenkov (HAWC) Observatory. The HAWC data are best described as a point-like source (HAWC J1746-2856) with a power-law spectrum ( d N / d E = ϕ E / 26 TeV γ ), where γ = −2.88 ± 0.15stat − 0.1sys and ϕ = 1.5 × 10−15 (TeV cm2 s)−1 ± 0.3 stat − 0.13 sys + 0.08 sys extending from 6 to 114 TeV. We find no evidence of a spectral cutoff up to 100 TeV using HAWC data. Two known point-like gamma-ray sources are spatially coincident with the HAWC gamma-ray excess: Sgr A* (HESS J1745-290) and the Arc (HESS J1746-285). We subtract the known flux contribution of these point sources from the measured flux of HAWC J1746-2856 to exclude their contamination and show that the excess observed by HAWC remains significant (>5σ), with the spectrum extending to >100 TeV. Our result supports that these detected UHE gamma rays can originate via hadronic interaction of PeV cosmic-ray protons with the dense ambient gas and confirms the presence of a proton PeVatron at the GC.
Publication Title
Astrophysical Journal Letters
Recommended Citation
Albert, A.,
Alfaro, R.,
Alvarez, C.,
Andrés, A.,
Arteaga-Velázquez, J.,
Avila Rojas, D.,
Groetsch, S.,
Hüntemeyer, P.,
Najafi, M.,
Turner, R.,
Wang, X.,
&
et. al
(2024).
Observation of the Galactic Center PeVatron beyond 100 TeV with HAWC.
Astrophysical Journal Letters,
973(1).
http://doi.org/10.3847/2041-8213/ad772e
Retrieved from: https://digitalcommons.mtu.edu/michigantech-p2/1159
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Version
Publisher's PDF
Publisher's Statement
© 2024. The Author(s). Published by the American Astronomical Society. Publisher’s version of record: https://doi.org/10.3847/2041-8213/ad772et