2024MNRAS.529.3593Z

We report a detection of GeV γ-ray emission potentially originating from the pulsar wind nebula in CTA 1 by analysing about 15 yr of Fermi Large Area Telescope data. By selecting an energy range from 50 GeV to 1 TeV to remove contamination from the γ-ray pulsar PSR J0007+7303, we have discovered an extended γ-ray source with a test statistic value of ∼44.94 in the region of CTA 1. The obtained flux is measured to be 6.71 ± 2.60 × 10^–12 erg cm^–2 s^–1 with a spectral index of 1.61 ± 0.36, which allows for a smooth connection with the flux in the TeV band. CTA 1 is also considered to be associated with 1LHAASO J0007+7303u, which is an ultra-high-energy source listed in the recently published catalogue of the Large High Altitude Air Shower Observatory. We assume that the radiation originates from the pulsar wind nebula and that its multiwavelength spectral energy distribution can be explained well with a time-dependent one-zone model.