Luminosity Function of Galaxies in the Nearby Universe: The Low-Luminosity End of the Nuclear Activity Sequence

[摘要] WepresentanestimateoftheshapeoftheluminosityfunctionsinthenearbyUniverseforthe4typesofextragalacticnuclearactivitycitedinHoetal.(1997a,AAA68.158.311),i.e.,HII,LINER,Transition,andSeyfertgalaxies,basedonamagnitudelimitedcompletesampleofobjectsselectedfromthesamework.Thissampleincludesquiteweakernuclearemissionobjectsthanconsideredinpreviousstudies,whichhasallowedustoassessthelow-luminosityendsofthenuclearactivitysequenceforeachtype.Itisfoundthatthreeoftheclasses(LINER,Transition,andSeyferts)haveverysimilarluminosityfunctionshapes,andbasicallyseemtodifferonlyintherelativenumbers.HIIobjectstendtobefoundindifferenthosts(lowerluminositygalaxies)andseemtohaveabimodalluminosityfunction,withafairlylargeproportionofIrranddwarfgalaxiesinthisclass,whicharesuperposedtoamoreSchechter-likeluminosityfunction.SeveralobservationalpropertiesalsosuggestthatTransitionobjectsareactuallyLINERscontaminatedbyHIIregions,andshouldbeincludedinthatcategory.Ourfitsfurthersuggestthepresenceofasubstantialnumberoflow-luminosityhostSeyfertsinthenearbyUniverse.ThedistributionofabsolutemagnitudesforSeyfertstype1and2isverysimilarinoursample.ThepossibilitythattheLINERclassencompassesseveraldifferentclassesofobjectsisalsodiscussed.

[学科分类] 天文学(综合)

[关键词] "galaxies: active";"galaxies: evolution";"galaxies: general";"galaxies: nuclei";"luminosity function"