Kinematic and Excitation Structure of the NGC 1068 Narrow-Line Region

摘要

WeinvestigatedthekinematicandexcitationstructureoftheNGC1068narrow-lineregion(NLR).Weobtainedprofilesofseveralemissionlines([Oiii]$$lambda$$5007,H$$eta$$,[Oi]$$lambda$$6300,and[Fevii]$$lambda$$6087)athigh-velocityresolution($$R$$$$sim$$7500a€“11000),andconfirmedthattheyshoweddifferentprofiles.TheseprofilesareusefulforunderstandingtheNLRstructure,sincetheycoverawideionization-potentialrange.Bycomparingtheresultswithaphotoionizationmodel,wefoundthat:(1)blueshiftedcomponentsatthecenterareverydense,(2)thoseinthenortheastregionhaveslightlylowerdensitiesthanthoseinthecenter,and(3)theionizationparametersoftheblueshiftedcomponentsincreasewithincreasingvelocitywithrespecttothesystemicvelocity.WeinvestigatedtheNLRstructureinNGC1068basedontheseresults.Weshowthatboththeobservedvelocitydependenceoftheionizationparameterandthegraduallyincreasingvelocityfieldcanbereproducedbyvaryingtheionizingcontinuumattenuation,assumingahollowedbiconicalgeometryandvaryingthecolumndensitiesofoutflowingclouds.