| Supernova remnants are important galactic gamma-ray sources and provide ex-tremely useful information for the study of physical processes such as the generation,acceleration and interaction of high-energy particles in extreme conditions.Starburst galaxies are new gamma-ray sources discovered by the Fermi Large Area Telescope,the origin of their high-energy radiation is still unknown.To study the high-energy as-trophysical physical processes of supernova remnants and starburst galaxies,reasonably explain their observation results,and discuss the origin of their high-energy particles are helpful to solve the century-old problem of the origin of galactic cosmic rays.Based on the latest Fermi-LAT observation,this paper studies the high-energy physical processes of supernova remnants and starburst galaxies,and the main achievements are as follows:1.The GeV radiation of the kepler’s supernova remnant.The kepler’s supernova remnant is a relatively young supernova remnant,originating the outburst in 1604,and whether it has a GeV-Te V high-energy radiation has always been a topic of concern.We analyzed the Fermi-LAT data for approximately 12 years and found that its photon flux in the energy range of 0.2-500 GeV was（4.85±0.60）×10-10cm-2s-1with a significance level of approximately 4σ.By analyzing properties of its light curve,no significant variation was found.By analyzing its location and energy spectral properties,we argue that the detected GeV radiation comes from the kepler’s supernova remnant.Using the NAIMA program,we further investigate the origin of its high-energy radiation and find that its GeV radiation may have a hadronic origin.2.GeV radiation from the composite supernova remnant COMP G327.1-1.1.In the Te V band,COMP G327.1-1.1 has a hard gamma radiation component,and its integral energy flux in the 1-10 Te V band is 1.12×10-12erg cm-2s-1,and the study confirmed that the Te V emission mainly came from PWN G327.15-1.04 in COMP G327.1-1.1.In fact,radio and X-ray observations also revealed that the morphology of the central PWN is formed by the interaction between the reverse shock wave inside the SNR and the low-energy ejecting material inside the SNR.In previous work,Fermi-LAT did not detect GeV gamma-ray emissions from the source.Using Fermi-LAT,we searched for potential GeV radiation from COMP G327.1-1.1 and found its significant gamma-ray radiation of 0.8-500 GeV with a approximately 4σsignificance level.Meanwhile,we analyzed the variation characteristics from its light curve of approximately 12 years,and did not find any significant variation characteristics.3.GeV radiation from asymmetric supernova remnant G317.3-0.2.SNR G317.3-0.2 is a shell-type supernova remnant composed of two asymmetrical inverse arcs.Pre-vious work found no significant gamma-ray radiation.We analyzed 12.2 years of Fermi-LAT pass 8 data using a two-dimensional Gaussian gamma-ray spatial distribution tem-plate,and found that the gamma-ray radiation significance level is about 8.13σ,its pho-ton flux in the 2-500 GeV energy range is（2.56±0.36）×10-9cm-2s-1,and its spectral index is 2.12±0.15.Through the analysis of characteristics of its light curve,no sig-nificant variability was found.The spatial location of the gamma-ray source is in good agreement with the position of SNR G317.3-0.2 at 843 MHz,and the characteristics of gamma-ray variability are consistent with those of most SNRs observed.4.GeV radiation from supernova remnant G272.2-3.2.SNR G272.2-3.2,as a bright X-ray supernova remnant,was initially detected by ROSAT,and it exhibited ther-mal radiation characteristics.Previous work did not detect its significant GeV gamma-ray emissions.We reanalyzed the Fermi-LAT pass 8 data and found that SNR G272.2-3.2 contains significant high-energy gamma-ray radiation with a soft spectral index and no significant variability from its light curve.By fitting its spectrum,the origin of its high energy radiation is discussed.5.High energy radiation from starburst galaxies.Previous studies have suggested that the high-energy radiation from starburst galaxies is dominated by hadronic inter-actions within supernova remnants.In this regard,we have also carried out relevant research work.We reanalyzed Fermi-LAT spectral data for the past 11 years.We used a simple single-region model and considered the hadronic origin to fit the high-energy radiation spectra of starburst galaxies and star-forming galaxies.In addition,except for NGC 1068 and NGC 4945,we found the power-law particle distribution with a expo-nentially cutoff that could well explain most of the observations of starburst galaxies.After that,we better explain the high-energy spectra of NGC 1068 and NGC 4945 by considering the two-zone model. |
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