Investigating a TeV-Halo Candidate around PSR J1928+1746 with HAWC

We present an updated High-Altitude Water Cherenkov (HAWC) analysis of the crowded Galactic-plane area near PSR J1928+1746, which was previously linked to the extended source 3HWC J1928+178. With 2904 days of HAWC data, improved event reconstruction, and a multicomponent likelihood model that includes six TeV source components and Galactic diffuse emission, we describe the region using six components and find a distinct, moderately extended source close to PSR J1928+1746. This source, HAWC J1928+1750, is detected from about 2 TeV to above 100 TeV and is well-described by a log-parabola spectrum with normalization K = 5.0 times 10-15 TeV-1 cm-2 s-1 at 12 TeV, index α= 2.09, curvature β= 0.35, and Gaussian extension σ= 0.19. Interpreting the emission using diffusion-halo templates under the assumption B = 8 μ G yields the diffusion coefficient D(100 TeV) = 2.1 times 10 27 cm squared s-1, which is about 500 times smaller than typical interstellar diffusion values at similar energies. This suggests that particle transport around PSR J1928+1746 is strongly suppressed under the TeV-halo interpretation. The TeV spectrum is consistent with leptonic inverse-Compton emission originating from pulsar-injected electrons and positrons, which requires less than approximately 1% of the pulsar's characteristic spin-down energy. However, a hadronic contribution from the surrounding environment cannot be excluded.