Observational Appearance of Relativistic, Spherically Symmetric Massive Winds

[摘要] Thephotonmeanfreepathinarelativisticallymovingmediumbecomeslonginthedownstreamdirection,whileshortintheupstreamdirection.Asaresult,theobservedopticaldepth,$$au$$,becomessmallinthedownstreamdirectionwhilelargeintheupstreamdirection.Hence,ifarelativisticsphericalwindblowsoff,theopticaldepthdependsstronglyonitsspeedandtheanglebetweenthevelocityandtheline-of-sight.Abramowicz,Novikov,andPaczynski(1991,ApJ,369,175)examinedsucharelativisticwind,andfoundthattheshapeofthephotosphereat$$au=1$$appearstobeconvexinthenonrelativisticcase,butconcaveforrelativisticvelocities.Wefurthercalculatedthetemperaturedistributionandluminosityofthephotospherebothinthecomovingandinertialframes.Wefoundthatthelimb-darkeningeffectwouldbestronglymodifiedintherelativisticregime.Wealsofoundthattheluminositiesofthephotospherebecomelargeasthewindspeedincreasesduetorelativisticeffects.Inaddition,theluminosityintheinertialframeishigherthanthatinthecomovingframe.Theseresultssuggestthattheobservedtemperatureandbrightnessinluminousobjectsmaybeoverestimatedwhentherearestrongrelativisticwinds.

[学科分类] 天文学(综合)

[关键词] "accretion;accretion disks";"black hole physics";"radiative transfer";"relativistic processes";"stars: winds"