摘要
Distance measurement of gamma-ray pulsars is a current challenge in pulsar studies.The Large Area Telescope（LAT） aboard the Fermi gamma-ray observatory discovered more than 70 gamma-ray pulsars including 24 new gamma-selected pulsars with almost no distance information.We study the relation between gammaray emission efficiency（η=Lγ/E˙） and pulsar parameters for young radio-selected gamma-ray pulsars with known distance information in the first gamma-ray pulsar catalog reported by Fermi/LAT.We have introduced three generation-order parameters to describe the gamma-ray emission properties of pulsars,and find a strong correlation of η-ζ3,a generation-order parameter which reflectsγ-ray photon generation in the pair cascade processes induced by magnetic field absorption in a pulsar＇s magnetosphere. A good correlation of η-BLC,the magnetic field at the light cylinder radius,is also found.These correlations are the distance indicators in gamma-ray pulsars used to evaluate distances for gamma-selected pulsars.Distances of 25 gamma-selected pulsars are estimated,which could be tested by other distance measurement methods.The physical origin of the correlations may also be interesting for pulsar studies.
Distance measurement of gamma-ray pulsars is a current challenge in pulsar studies.The Large Area Telescope（LAT） aboard the Fermi gamma-ray observatory discovered more than 70 gamma-ray pulsars including 24 new gamma-selected pulsars with almost no distance information.We study the relation between gammaray emission efficiency（η=Lγ/E˙） and pulsar parameters for young radio-selected gamma-ray pulsars with known distance information in the first gamma-ray pulsar catalog reported by Fermi/LAT.We have introduced three generation-order parameters to describe the gamma-ray emission properties of pulsars,and find a strong correlation of η-ζ3,a generation-order parameter which reflectsγ-ray photon generation in the pair cascade processes induced by magnetic field absorption in a pulsar＇s magnetosphere. A good correlation of η-BLC,the magnetic field at the light cylinder radius,is also found.These correlations are the distance indicators in gamma-ray pulsars used to evaluate distances for gamma-selected pulsars.Distances of 25 gamma-selected pulsars are estimated,which could be tested by other distance measurement methods.The physical origin of the correlations may also be interesting for pulsar studies.
基金
supported by the National Natural Science Foundation of China(Grant Nos.10803009,10833003 and 11073030)
