Are TeV-PeV observations unveiling the full extent of particle escape in pulsar-powered sources?

Observations of the Milky Way at TeV to PeV photon energies have revealed a rich population of sources with significant angular extension and positionally coincident with energetic pulsars. In this work, we assessed whether the properties of these gamma-ray sources are consistent with the predictions of a model for the non-thermal leptonic emission of a pulsar wind nebula expanding within a supernova remnant, including the possibility of particle escape across the different components of the system and up to the surrounding ambient medium. Model predictions for a small number of typical systems are compared to data from source catalogs issued by the H.E.S.S. and LHAASO collaborations. Observations in the 1 − 10 TeV range explored with H.E.S.S. or LHAASO-WCDA, and in the 20 − 100 TeV range explored by LHAASO-KM2A can be accounted for only when a high degree of particle escape is implemented. Particle escape therefore seems to be a very important process in young SNR-PWN systems with ages in the 1 − 100 kyr range, and to have major consequences on their appearance as TeV/PeV sources.