4HWC J2029$+$3641: a Pulsar Wind Nebula Powered by PSR J2030$+$3641?

Abstract

4HWC J2029+3641 is a newly discovered point source detected by HAWC, with no previously identified TeV counterpart. The gamma-ray pulsar PSR J2030+3641, located 0.1 degree from the source center, is a middle-aged pulsar showing spin parameters similar to Geminga. Using Fermni-LAT data spanning from August 2008 to February 2026, we performed binned maximum likelihood spectral analysis in the energy range from 300 MeV to 1 PeV. A phase-resolved analysis was conducted to separate the off-peak and on-peak emissions. No significant spatial extension was found for the off-peak component. The off-peak spectrum exhibits strong curvature and is best described by an exponentially cutoff power-law model. The observed radio-to-gamma phase lag and narrow peak separation favor an outer-gap model for the gamma-ray emission.