Time-Resolved Spectral Variability of the Prompt Emission from GRB 070125 Observed with Suzaku/WAM

摘要

Time-resolvedspectralanalysesofGRB070125withsignificantphotondetectionsovertheMeVregimeusingSuzaku/WAMdataarereported.Thepromptemissionintervalwasdividedinto10timeregions,andtheirspectrawerereproducedbyaBandfunctionoracutoffpower-lawmodel.Thespectrashowacomplexevolution;asoft-hard-softtrendisseen,ratherthanatypicalhard-to-softmonotonicvariation.Inaddition,aflatspectralslopeinthelow-energybandexceedingtheslopeexpectedfromasimplesynchrotronemissionmodelissuggestedinoneofthetimeregions.TheseresultsimplythattheinternalshocksintherelativisticjetofGRB070125havedifferentphysicalconditions.Thereisapossibleexcessat$$sim$$2.2MeVinthespectrumof33secondsafterthetriggeratasignificantlevelof$$approx$$98.5%,wherethecontinuumspectrumisnotreproducedbytheBandfunction.Thesepropertiesareonlyshownduringtheshortprompttimeintervalofthepromptemission,andemphasizetheutilityoftheSuzaku/WAMforthestudyofgamma-raybursts.