Exploring the nature of Galactic PeVatron candidates from X-ray to TeV energies

The detection of Ultra-High-Energy (UHE) gamma rays from twelve Galactic sources, recently reported by the LHAASO collaboration, has catalyzed further excitement in the long-standing quest for Galactic PeVatrons. Most of the LHAASO sources, detected up to above 1 PeV, are possibly associated with energetic pulsars. Furthermore, pulsar wind nebulae (PWNe) constitute the largest class of identified very-high-energy (VHE) gamma-ray emitters in the Milky Way, with the Crab Nebula remaining the only firmly associated PeVatron in UHE gamma rays. These findings suggest that PWNe are effective PeV particle accelerators.

Through a joint effort entailing broad-band high-energy observations with NuSTAR, Fermi-LAT, VERITAS and HAWC, we aim to investigate the properties of a heterogeneous group of eight middle-aged TeV-bright PWNe, to understand the nature and physical properties of these sources and the acceleration mechanisms that power their multi-wavelength emission. In this contribution, we provide an update on the project status, and present our detailed study of G106.65+2.96 (also known as the Boomerang PWN) powered by the energetic pulsar PSR J2229+6114. We report on the detection of extended X-ray emission up to 20 keV with NuSTAR and the results from a dedicated analysis of 13 years of Fermi-LAT data and VERITAS archival observations of the region.