Models for Accretion-Disk Fluctuations through Self-Organized Criticality Including Relativistic Effects

[摘要] ThepossibilitythatsomeoftheobservedX-rayandopticalvariabilityinactivegalacticnucleiandgalacticblackholecandidatesareproducedinaccretiondisksthroughthedevelopmentofaself-organizedcriticalstateisreconsidered.Newsimulations,includingmorecompletecalculationsofrelativisticeffects,doshowthatthismodelcanproducelight-curvesandpower-spectraforthevariabilitywhichagreewiththerangeobservedinopticalandX-raystudiesofAGNandX-raybinaries.However,theuniversalityofcompleteself-organizedcriticalityhasnotquitebeenachieved.Thisismainlybecausethecharacterofthevariationsdependquitesubstantiallyontheextentoftheunstablediskregion.Ifitextendsclosetotheinnermoststableorbit,aphysicalscaleisintroducedandthescale-freecharacterofself-organizedcriticalityisvitiated.Asignificantdependenceofthepowerspectrumdensityslopeonthetypeofdiffusionwithinthediskandaweakerdependenceontheamountofdifferentialrotationarenoted.Whengeneral-relativisticeffectsareincorporatedinthemodels,additionalsubstantialdifferencesareproducedifthediskisviewedfromdirectionsfarfromtheaccretiondiskaxis.

[学科分类] 天文学(综合)

[关键词] "accretion;accretion disks";"black hole physics";"galaxies: active";hydrodynamics;"relativistic processes";"X-rays: stars"