摘要：Aims.The supernova remnant (SNR) G150.3+4.5 was recently discovered in the radio band; it exhibits a shell-like morphology with an angular size of ~ 3°, suggesting either an old or a nearby SNR. Extendedγ-ray emission spatially coincident with the SNR was reported in theFermiGalactic Extended Source Catalog, with a power-law spectral index of Γ = 1.91 ± 0.09. Studying particle acceleration in SNRs through theirγ-ray emission is of primary concern to assess the nature of accelerated particles and the maximum energy they can reach.Methods.Using more than ten years ofFermi-LAT data, we investigate the morphological and spectral properties of the SNR G150.3+4.5 from 300 MeV to 3 TeV. We use the latest releases of theFermi-LAT catalog, the instrument response functions and the Galactic and isotropic diffuse emissions. We use ROSAT all-sky survey data to assess any thermal and nonthermal X-ray emission, and we derive minimum and maximum distance to G150.3+4.5.Results.We describe theγ-ray emission of G150.3+4.5 by an extended component which is found to be spatially coincident with the radio SNR. The spectrum is hard and the detection of photons up to hundreds of GeV points towards an emission from a dynamically young SNR. The lack of X-ray emission gives a tight constraint on the ambient densityn0≤ 3.6 × 10−3cm−3. Since G150.3+4.5 is not reported as a historical SNR, we impose a lower limit on its age oft= 1 kyr. We estimate its distance to be between 0.7 and 4.5 kpc. We find that G150.3+4.5 is spectrally similar to other dynamically young and shell-type SNRs, such as RX J1713.7−3946 or Vela Junior. The broadband nonthermal emission is explained with a leptonic scenario, implying a downstream magnetic field ofB= 5μG and acceleration of particles up to few TeV energies.
关键词：Key wordsencosmic raysISM: supernova remnantsgamma rays: ISM
