Two Candidate Pulsar TeV Halos Identified from Property-similarity Studies

Abstract Teraelectronvolt halos have been suggested to be a common phenomenon associated with middle-aged pulsars. Based on our recent work on the middle-aged pulsar J0631+1036, which is the only known source positionally coincident with a hard teraelectronvolt γ -ray source and likely powers the latter as a teraelectronvolt halo, we select three candidate teraelectronvolt halos from the first Large High Altitude Air Shower Observatory (LHAASO) catalog of γ -ray sources. The corresponding pulsars, given by the positional coincidences and property similarities, are PSR J1958+2846, PSR J2028+3332, and PSR J1849-0001. We analyze the gigaelectronvolt γ -ray data obtained with the Large Area Telescope on board the Fermi Gamma-ray Space Telescope for the first two pulsars, as the last is γ -ray quiet. We remove the pulsed emissions of the pulsars from the source regions from timing analysis, and determine that there are no residual gigaelectronvolt emissions in the regions as any possible counterparts to the teraelectronvolt sources. Considering the previous observational results for the source regions and comparing the two pulsars to Geminga (and Monogem), the LHAASO-detected teraelectronvolt sources are likely the pulsars’ respective teraelectronvolt halos. We find that the candidate and identified teraelectronvolt halos, including that of PSR J1849-0001, have luminosities at 50 TeV (estimated from the differential fluxes) approximately proportional to the spin-down energy E ̇ of the pulsars, and the ratios of the former to the latter are ∼6 × 10 −4 .