Photon Emission in a Cascade from Relativistic Protons Initiated by Residual Thermal Photons in Gamma-Ray Bursts

Publications of the Astronomical Society of Japan

Takahara, Fumio¹  Asano, Katsuaki¹ 

[1] Department of Earth and Space Science, Osaka University, Toyonaka 560-0043 ,

关键词: "gamma-ray burst: general";    non-thermal;    "radiation mechanisms: shock waves";   

DOI  :  10.1093/pasj/55.2.433

学科分类：天文学(综合)

来源: Oxford University Press

【 摘 要 】

Gamma-rayburstsaregenerallyconsideredtobetheresultofinternalshocksgeneratedinaninhomogeneousrelativisticoutflowthatarisesfromafireball.Insuchshocks,theFermiaccelerationofprotonsisnaturallyexpectedtobeatleastasefficientasthatofelectrons.Weinvestigatetheconsequencesofprotonaccelerationintheresidualthermalphotonfieldofafireball,especiallythoseontheemissionspectraofphotons.Incontrasttomostotherstudies,wedonotinvokeadirectelectronaccelerationinshockwaves.Weshowthattheresidualradiationfieldofthefireballcanignitethephotopionproductionandsubsequentcascade,andthatthephotonsemittedinthisprocessfurtherenhancethephoton-initiatedcascade.WefindthatFermi-acceleratedprotonswith$$gtrsim10^{13},mathrm{eV}$$efficientlybringtheirenergyintopionproductionandsubsequentphotonemission.Theparticlescascadingfromthepionsemitphotonsoverawideenergyrange.Thephotonsemittedfromelectron–positronpairsdistributecontinuouslyfromtheGeVrangedowntotheX-rayrange,whilemuonscanemitgamma-raysbysynchrotronradiationwithabreakataround1–10MeV.WealsodiscussseveralradiationprocesseswhichmaypossiblyproduceabreakfeatureintheMeVrange,asobservedinadditiontomuonsynchrotronradiation.

【 授权许可】

Unknown