Speaker
Description
The First LHAASO Catalogue of Gamma-ray Sources (1LHAASO) lists 90 sources, 43 of which show ultra-high-energy (UHE) emission extending beyond 100 TeV, raising pressing questions about the identity of the underlying PeVatrons. A multiwavelength characterization of these sources is essential to constrain the particle acceleration mechanisms at work. We present a systematic search for low-frequency radio counterparts to the 57 1LHAASO sources that fall within the footprint of the LOFAR Two-Meter Sky Survey (LoTSS DR-3), which covers a substantial fraction of the Galactic plane at 144 MHz with 6″ resolution.
For sources in the inner Galaxy, we combine LOFAR data with MeerKAT 1.3 GHz images from the SARAO MeerKAT Galactic Plane Survey (SMGPS) to construct spectral index maps that distinguish thermal from non-thermal emission, directly informing the SNR versus H II region nature of candidate counterparts. In the outer Galaxy, where source confusion is lower, we identify several new SNR and PWN candidates coincident with 1LHAASO sources, including a new SNR/PWN candidate (G123.4+1.0) associated with 1LHAASO J0056+6346u, located within a ~3° molecular cavity. In the inner Galaxy, we find that the majority of 1LHAASO sources in the first quadrant are coincident with known SNRs, SNR candidates, or thermal emission complexes, and we identify several new SNR candidates from the LOFAR data alone.
These results demonstrate the power of low-frequency, high-resolution radio surveys as a tool for the identification and classification of Galactic PeVatron candidates detected by LHAASO.
