Relativistic Radiative Transfer in Relativistic Planea€“Parallel Flows: Roles of Scattering Effect

摘要

Relativisticradiativetransferinarelativisticplanea€“parallelflowhasbeenreexaminedunderanon-graytreatment,whilefocusingourattentiononthescatteringeffect.UndertheassumptionofaconstantflowspeedandusingavariableEddingtonfactor,weanalyticallysolvedtherelativistictransferequationsinthecomovingframeforseveralcases,suchasradiativeequilibriumorlocalthermodynamicalequilibrium,andobtainedanalyticalsolutionsfortheemergentintensityaswellasotherradiativequantities.Inthecaseoftheradiativeequilibrium,thescatteringeffectdoesnotappear,andthesolutionsareformallythesameasthoseunderthegraycase,althoughthefrequency-dependentintensitywasobtainedforthefirsttime.Inthecaseoflocalthermodynamicequilibrium,ontheotherhand,thescatteringeffectissignificantinisothermalflow,similartoastaticisothermalatmosphere.Thatis,thesourcefunctionreducesneartotheflowtop,andtheemergentintensitydecreasestowardthelimbduetoscattering.Inbothcases,whentheflowopticaldepthbecomessmall,theemergentintensitytowardthepoledecreasesduetotheeffectofafiniteopticaldepth.Inaddition,theemergentintensityandotherquantitiesinthefixed(inertial)frameareenhancedduetorelativisticeffects.