Studies on the VHE spectrum of the radio galaxy M87 observed by HAWC

We report the detection of TeV gamma-ray emission from M87 with the High Altitude Water Cherenkov (HAWC) observatory, marking the first time its time-integrated TeV spectrum has been measured over an extended period of approximately 6 years. The emission is consistent with a power-law spectrum with index α = 2.53 ± 0.29 and flux normalization (7.09 ± 1.24) × 10⁻¹³ cm⁻² s⁻¹ TeV⁻¹ at 1 TeV, extending up to 26.5 TeV at a 1σ confidence level. This result provides the most detailed characterization of the very-high-energy (VHE) emission of M87, derived from the longest temporal coverage up to date, and offers new constraints on particle acceleration in radio galaxies.