19 96ApJS. .106 . .341M rence LivermoreNational Laboratory,Livermore,CA 94550. under acooperative agreementwiththeNationalScience Foundation. Optical AstronomyObservatories, whichisoperatedbyAURA,Inc., the hostgalaxyislikelytoconfuse mattersfurtherinlower whether boththeX-rayand IRemissionariseinacommon nonthermal (synchrotron)source. Infraredemissionfrom marily thermal(perhapsfromX-ray-heateddust) or remains unclearwhethertheIRemissioninAGNsis pri- nucleus andthenatureofitsenergysource.However, it principle, lendinsighttothephysicalconditionsin the current starformationrate.Foractivegalaxies, the found thatthiscorrelationisadirectconsequenceof the relationship betweeninfraredandX-rayemissioncould, in luminosities. Inmoreactivestar-forminggalaxies, they a strongcorrelationbetweentheirX-rayandfar-infrared drawn fromtheIRASBrightGalaxySampleandobserved X-ray propertiesofpredominantlynon-AGNgalaxies emission. David,Jones,&Forman(1992)examinedthesoft relationship betweentheassociatedX-rayandinfrared understanding thenatureofbothtypesactivityis to aburstofstarformation.Onethekeyelementsfor linked toacompact,activenucleus(AGN),andthat The AstrophysicalJournalSupplementSeries,106:341-397,1996October © 1996.TheAmericanAstronomicalSociety.Allrightsreserved.PrintedinU.S.A. 2 1 Presentaddress: InstituteofGeophysicsandPlanetary Physics,Law- VisitingAstronomer,KittPeak NationalObservatory, Activity inlate-typegalaxiescomestwovarieties:that Subject headings:galaxies:active—Seyfertinfrared:galaxiesX-rays: X-ray background. which suchopticallyinnocuous,obscuredAGNscouldcompriseanimportantnewcomponentofthe nucleus islikelytoexplaintheX-rayandopticalpropertiesoftheseobjects.Wedescribeascenarioin is actuallyamemberoftheIZw1class.Theenigmaticstarburst/Seyfertcompositegalaxieshaveoptical other linesinthespectrumand,somecases,aweak,broadHacomponent.Obscurationofactive Close examinationoftheiropticalspectrarevealssubtleSeyfertsignatures:[Om]linesbroaderthanall spectra dominatedbythefeaturesofHngalaxiesbutX-rayluminositiestypicalforSeyfertgalaxies. with surprisingfrequency:IZw1objects(alsocallednarrow-lineSeyfertgalaxies)andstarburst/ object 202103—223434(=IRAS201812244),reportedtobethebestexampleofanarrow-linequasar, extragalactic X-raysourcesareactivegalacticnuclei(AGNs),consistentwiththeresultsofprevious Seyfert compositegalaxies,anewclassofluminousX-raysources.WehaveshownthattheBoileretal. studies ofX-ray-selectedobjects.However,manytheseAGNsexhibitweakorheavilyreddened normal spiralgalaxieswastobefoundinthissample,wefindnoevidenceforsuchaclass.Mostofthe Seyfert featuresintheiropticalspectra.Inaddition,tworaretypesofAGNsarefoundthissample chance coincidencesinvolvebrightstarsorSeyfertgalaxiesclose(inprojection)toIR-brightHngal- for thefirsttime.AlargenumberofIR/X-raysourcechancecoincidencesarefoundinthissample; axies. AlthoughthisworkwasmotivatedinitiallybythereportthatanewclassofX-ray-luminous, fications havebeendeterminedfor210ofthe241X-raysourcesincatalog;105arepresentedhere (1992) catalogofIRASsourcesdetectedintheROSATAll-SkySurvey.Thishasinvolvedcarefuloptical the 40-50expected,wehaveidentified18firmlyandestablishedstrongcasesfor29others.Most spectroscopy, areviewoftheliterature,andeffortstorevealcontaminantsinsample.Classi- have carriedoutanextensiveprogramtoobtainaccuratespectroscopicclassificationsoftheBoileretal. known tobeluminousinfraredsources,contributesignificantlythecosmicX-raybackground,we © American Astronomical Society • Provided by theNASA Astrophysics Data System To explorethepossibilitythatstar-forminggalaxiesorobscuredSeyfertgalaxies,bothofwhichare 1. INTRODUCTION CLASSIFICATION OFIRAS-SELECTEDX-RAYGALAXIESINTHE Department ofAstronomy,ColumbiaUniversity,538West120thStreet,NewYork,NY10027 1,2 Edward C.Moran,JulesP.Halpern,andDavidJ.Helfand Received 1995April6;accepted1996March15 ROS ATALL-SKYSURVEY ABSTRACT (e.g., Madau, Ghisellini, &Fabian1994) could explainthe origin ofthesoft andhardX-raybackgrounds havebeen (Griffiths &Padovani1990) orobscuredSeyfertgalaxies scenarios forthewayin whichstar-forminggalaxies hard asthatoftheXRB(Fabian &Barcons1992).Plausible been showntohaveacharacteristic broadbandspectrumas energies, sincenoclassofextragalactic X-raysourceshas that contributessignificantly totheXRBathigherX-ray cant contributiontothesoftXRB(Maccacaroetal.1991; Boyle etal.1993).Acriticalneedexistsforaclassofobjects (Persic etal.1989;Griffiths&Padovani1990;Green al. nous infraredsources,arealreadyknowntomakeasignifi- the softXRB(below~2keV)asbetween5%and40% bution ofinfrared-emittingnormalandstarburstgalaxies to ground (XRB).Variousauthorshaveestimatedthecontri- useful forelucidatingtheoriginofcosmicX-rayback- X-ray/IR studiesofactivegalaxies,usinghomogeneous should helptoclarifytheissue. samples thatbetterrepresentvariousAGNsubclasses, nonthermal sourcescontributeinvaryingproportionsto the continuaofAGNs(Osterbrock1991).New,larger contradictory results(seeGreen,Anderson,&Ward1992, X-ray/IR luminositycorrelationsinAGNshaveyielded 1992; Davidetal.1992).AGNs,whicharefrequentlylumi- and referencestherein).Inalllikelihood,boththermal luminosity AGNs.Itisnosurprise,then,thatsearchesfor X-ray andinfrared-selectedsamplesmayalsoprove 19 96ApJS. .106 . .341M 42-1 41_1 42445-1 which members ofthesamplewerelikely to bethesechance (>16%) mustbechancesuperpositions betweenROSAT and IRASsources, theymadenoattempt todetermine Although theyacknowledged thatacertainfraction on thebasisofIR/X-ray sourcepositionoffsets. infrared propertiesasafunctionofobjectclass,ispresented. cidences. Severalinterestingsubclassesarefoundin this sample, whichwediscussinthecontextofXRB §6. which entriesinthecatalogarelikelytobechancecoin- follows in§4,and5wepresentourassessment of compilation ofX-ray,IRandopticaldataforthesesources just over10ergss.Ourfollow-upASCAobservationof Finally, in§7,anoverallcomparisonoftheX-ray and spectral atlasofinfrared-andX-ray-emittinggalaxies. A new opticalspectra,whichconstitutealarge,representative sources. Theseresultsarepresentedin§3,alongwith our established classificationsforatotalof210the241 B92 drawn fromopticalfindingchartsoftheobjects,wehave bined withourownsearchoftheliteratureandinferences classifications for93X-raysourcesinthecatalog.Com- resolution opticalspectratoobtainaccuratespectroscopic chance coincidences.Wehavethenusedmoderate- which IR/X-raysourcematchesaregenuineand connections toactivityingalaxies.In§2,wediscussthe minimum, thecompleteclassificationofB92samplewill statistical contentoftheB92sample,necessarytoevaluate provide importantnewinformationabouttheX-rayandIR new componentsofthecosmicX-raybackground.Ata L Hiigalaxies,obscuredSeyfertorotherpossible X-ray sourcesinthecatalog,toextendsearchforhigh- embarked onaprogramtoidentifyandclassifyallthe alous X-rayluminosities. luminosity isatmost4x10ergss(Moran,Helfand,& NGC 3256,however,indicatesthatits0.3-10keVX-ray unexamined atopticalwavelengths,however,andwehave Lehnert 1996b).Thus,noneofthese17objectshaveanom- firmed X-raysource;itsreportedRASSluminosityis four actualHngalaxies,onlyone,NGC3256,isacon- found thatmost(13)wereinfactpreviouslyunrecognized (Moran, Halpem,&Helfand1994,hereafterPaperI)and AGNs, somewithverysubtleSeyfertcharacteristics.Ofthe their potentialimportancetotheproblemofXRB X-ray bandby1-3ordersofmagnitude.Wereexaminedthe spectral classificationsof17thesegalaxiesbecause most luminousnormalspiralsdetectedpreviouslyinthe broad emission-lineSeyfertgalaxiesbutexceedthoseofthe luminous normalspiralgalaxiesandstarbursts,withL= interesting resultwastheirreportofasubset20X-ray- x literature anddeterminedtheirX-rayluminositiesL.One wavelengths and,becauseitwasconstructedfromtwo (RASS), waspubhshedbyBoileretal.(1992;hereafterB92). of theobjects,B92foundclassificationsandredshiftsin all-sky surveys,thesampleisinprincipleunbiased.For104 in IR-selectedsamples. It isthelargestsinglecollectionofobjectsdetectedatboth objects, culledfromacross-correlationoftheIRASPoint proposed. Bothtypesofsourcesareexpectedtobepresent 10-10* ergss.Suchluminositiesaretypicalfor Source Catalog(PSC)andtheROSATAll-SkySurvey x 342 x 2. STATISTICALPROPERTIES OFTHEPSC/RASSSAMPLE B92 definedtheirsampleof IRAS/ROSATobjectssolely The majorityoftheobjectsinB92sampleremain Recently, acatalogof241infrared-andX-ray-emitting © American Astronomical Society • Provided by theNASA Astrophysics Data System MORAN, HALFERN,&HELFAND 2 entry hasbeendeleted fromtheRASSsourcelist(Boiler 1993).Thus,there are 241,not244,unique IR/X-raysourcematchesin the B92catalog. closest tothegalaxyopticalposition tobethecorrectassociation.In with them.OnlyoneIR/X-raycoincidence isgenuineinthesecases,sothe addition, oneoftheX-raysources originally associatedwithaB92catalog other coincidencemustbebychance. WehavetakentheX-raysource two IRASgalaxiesinthesamplehave twoRASSsourceseachassociated ray positionoffsetsA, which indicatesastrongposi- fied X-raysources,excludingfourLargeMagellanicCloudsourcesandthe those withIRAS/POSATsourcepositionoffsetsoflessthan entries intheB92catalogarelikelytobespurious. nearby irregulargalaxyUGC4305,forwhichAxisuncertain. distribution ofoptical/X-raypositionoffsetsAforthesubsetidenti- revealing astrongpositionalcorrelationatoffsetslessthan40".(b)The of theX-raysourcepositions,optical/X-rayposition the RASSX-rayposition(Brinkmann,Sichert,&Boiler offset distributionshouldindicatestraightforwardlywhich rate thantheIRASpositions.Ithasbeenclaimedthat70% desirable becausetheopticalpositionsarefarmoreaccu- distribution ofoptical/X-raypositionoffsetsaswell.Thisis coincidences contributeaconstantamounttoeachoffsetbin,clearly of theopticalcounterpartstoRASSsourcesliewithin20" of now identifiedoptically;thus,itispossibletoderivethe distribution. However,alargefractionofIRASobjectsare issue begins,therefore,withtheIR/X-raypositionoffset coincidences. Ourinvestigationofthechancecoincidence solid anglen(dl—Of),inunitsofarcsec.Graphedthismanner,chance 100". InFigurelawehaveplottedthedistributionofIR/X- number ofsourceswithoffsetbetween0!anddhasbeendividedbythe for theentireB92catalog,derivedfromoffsetspublishedbyB92.The 1994); therefore,intheabsenceofsystematicdisplacements IR/X 0/ 0/x 2 3 3 ThecatalogpublishedbyB92actually contains244entries.However, The 241objectsintheB92catalogwereselectedtobe Fig. 1.—(a)ThedistributionofIR/X-raysourcepositionoffsets 2.1. IR/X-RayPositionOffsets Position Offset(arcsec) Vol. 106 19 96ApJS. .106 . .341M cedure hasprogressed, isplottedinFigure lb.Thereare distribution, which hasevolvedasourclassification pro- optical counterpartoftheIRAS source.ThecurrentA plication. and itsopticalcounterpart, nottheX-raysourceand source coincidence,Awas calculatedfortheX-raysource our findingchart.Intheinstance ofachanceIR/X-ray offsets formuchofthesample,eliminatingthiscom- position oftheX-raysource anditsopticalcounterparton X-ray sourcelistedbyB92toitspublishedopticalposition, possible toobtainandanalyzetheoptical/X-rayposition or fromdirectmeasurement oftheseparationbetween source, Awasobtainedbycomparingthepositionof the position offsetdistribution.ForeachidentifiedX-ray optically identifiedandhavewell-determinedpositions, itis However, sincesuchalargefractionoftheB92objectsare analysis mustincorporatetheerrorellipseinformation. position errorellipses,notcircles,andaproper tion analysisisthefactthatIRASsourceshaveassociated chance coincidences. permitted anaccuratedeterminationoftheoptical/X-ray optical counterparts,discussedbelowin§§3and4, has 0/x 0/x satisfying thisseparationcriterion.Thesefiguresimplythat positions wouldbeexpectedamongthe171coincidences coincidences withA<40",onlysevenchancesuper- correct. Notethatifthesamplehadbeenlimitedtothose value of40chancecoincidencesquotedbyB92couldbe 0/x tain surfacedensitydistributionofRASSsources.Thus,the ~ 50%oftheB92catalogentrieswithA>40"are of thenumberchancecoincidencesbecauseuncer- the RASSdata,wecannotmakeamoreaccurateestimate are expectedforA,<100".However,withoutaccessto uniform sourcedistributions,that50chancecoincidences and B92considered14,708IRASsources.Wecalculate,for approximately thisnumber.TheRASScontainsabout derived, althoughthecalculationdescribedaboveyields their samplewithoutexplaininghowthisestimatewas coincidence rate. 56,000 sources(Brinkmannetal.1994)over97%ofthesky, calculations shouldbeperformedonsubsetsofthecatalogs distributed uniformlyonthesky,chancecoincidence be summedtogiveamoreaccurateestimateofthechance uniform; theresultsofindividualcalculationscanthen NaA. Inprinciple,ifsourcesineithercatalogarenot catalog 2isgivensimplybyaxA.Thetotalnumberof over whichthesourcedistributionsareapproximately resented byAfortheentirecross-correlationisthen chance coincidencesexpectedwithintheangularrangerep- circle orannulusofsolidangleAcenteredonasourcein cidences expectedtoresultfromthecross-correlationoftwo value ofthenumbersourcesincatalog1thatfallwithina IR/X overlap. Fortwouncorrelatedcatalogs,theexpectation second catalogintheareaofskywheretwocatalogs one catalogandthetotalnumberofsourcesNin source catalogsgiventhesurfacedensitya!ofsourcesin sources, asafunctionofA,arechancecoincidences. alone doesnotallowustodeterminewhatfractionof tional correlationforA,<40".Unfortunately,thegraph IR/X R/X No. 2,1996 21 2 IR/X R/X The identificationofthemajorityB92X-raysource Another factorcomplicatingtheIR/X-rayoffsetdistribu- B92 claimthat40chancecoincidencesareexpectedin It ispossibletocalculatethenumberofchancecoin- © American Astronomical Society • Provided by theNASA Astrophysics Data System 2.2. Optical/X-rayPositionOffsets //MS-SELECTED X-RAYGALAXIES redshifts, weselected thosepreviouslyclassified normalgal- “ Sab”).Next,usingtheX-ray luminositiesquotedbyB92 lacking previousclassifications andredshifts.Thisincludes or thosewecomputedusing theROSATPositionSensitive objects withmorphological classificationsonly(e.g., following manner.First,after consultingtheNASA/IPAC few spectra. Proportional Counter (PSPC)countrates andpublished calibration problems,especiallyabove~6500Â,persist ina lower andupperwavelengthlimits.Forthemostpart, we maximum wavelengthcoverage,eventhoughtheflux cali- Extragalactic Database(NED), weselectedallobjects have copedsuccessfullywiththeseproblems.However, flux bration forbothsetsofspectracanbeuncertainat the further fortheGoldcamspectra.Nonetheless,wehavetried to useasmuchofthedatapossibleobtain the of thetime-variable2mtelescopefocuscomplicatesmatters red andblueendsofthespectrum.Thewell-knownproblem compromise theimagequalityandspectralresolutionat the for suchlargedetectors;thus,vignettingandaberrations length coverageatthemoderateresolutiondiscussedabove. format CCDs.Theseoffertheadvantageofbroadwave- chance IR/X-raycoincidenceswerediscoveredusingthis Unfortunately, thespectrographopticswerenotdesigned procedure. well asotherobjects(ifany)neartheX-rayposition.Several large separations,weobservedthelikelyIRASobjectas positions; weobservedbothobjectsinallsuchinstances. quently, pairsofgalaxieswerefoundnearthePSC/RASS (Filippenko 1982).Insomecases,theslitwasorientedsoas minimize theeffectsofdifferentialatmosphericrefraction For mostcasesinwhichtheX-rayandIRpositionshave although thiswasneverdoneathighairmass.Quitefre- to includetwonearbyobjectsinthesameexposure, ensure thatweobtainedspectraofsufficientsignal-to-noise sible, weorientedtheslitatornearparallacticangleto (FWHM). The4mspectraspanthe4300-7800Ârangeat 2 m,andfrom5to15minutesatthe4m.Wheneverpos- ratio, integrationtimesrangedfrom15to45minutesatthe classifications; therefore,weobservedoverawidewave- January andJulyusingtheGoldcamSpectrograph,at the wavelengthrange3700-7400Âwith~4.5Aresolution length bandatmoderateresolution.The2mspectracover carried outattheKPNO2mtelescopeduring1994 Spectrograph. Ourobjectivewastoderiveaccuratespectral the KPNO4mtelescopein1994MayusingRC distribution ofAtoidentifylikelycontaminantsinthe published opticalpositionswehaveused.In§5,usethe published intheB92catalogorinaccuracies similar. ThefractionofX-raysourceswithAq/x<20"is ray andoptical/X-rayoffsetdistributionsaresurprisingly slight differencesbetweenFigureslaandlb,buttheIR/X- ~5 Âresolution.A2"slitwasusedinallthreeruns.To reflect systematicerrorsintheX-raysourcepositions B92 catalog. RASS byBrinkmannetal.(1994).Thisdifferencecould 55%, somewhatlowerthanthevalueof70%claimedfor 0/x The B92objectswechosetoobservewereselectedinthe Both theGoldcamandRCSpectrographsnowuselarge- Optical spectroscopyofthePSC/RASSsourceswas 3. OPTICALSPECTROSCOPYANDSPECTRAL CLASSIFICATION 343 19 96ApJS. .106 . .341M -1 41-1 42-1 411 42-1 (e.g., 101654-1-732355).Interestingly, twotypesofgalaxies entirely adequatearefound withsignificantfrequencyin for whichthestandardclassification schemesarenot line Seyfert1galaxies) andstarburst/Seyfert compositegal- this sample.These areIZw1objects(also callednarrow- cult toclassifyaccuratelybecause theircontinuuaaredomi- (S/N) spectraareavailable. A fewothergalaxieswerediffi- nated bystarlight,whichswamps theirweakemissionlines Terlevich 1992).Wearetentativelygivingsuchgalaxies 043829 —142421foranexample).Withthislimitedinforma- Seyfert 2classificationsuntilbettersignal-to-noiseratio axies (LINERs),ornormalHngalaxies(seeFilippenko & tion, itisimpossibletodetermineifthesegalaxies are ently reddenedobjectsthathaveonly[Nn],Ha,andweak normal/active galaxyboundary;seethespectrum of few emissionlinestoclassifyaspectrumusingthestandard Seyfert 2’s,low-ionizationnuclearemission-lineregion gal- F(Ha) «1andvelocitywidthsof~300kmsFWHM (on flux-ratio diagnosticdiagrams(Veilleux&Osterbrock straightforward. Insomeinstances,however,thereweretoo active galaxies.Theclassificationofmostgalaxieswas fication, andanyothercatalognamestheobjectmayhave. [S ii]emissionlineswithfluxratiosF([Nn]26583)/ axies fromAGNs,andtodeterminethepropersubclassfor sion linesinthespectrumtodistinguishnormal/Hngal- on boththevelocitywidthsandintensityratiosofemis- Our spectralclassificationscheme,detailedinPaperI,relies panied bytheJ2000RASSsourceposition,ourclassi- X-ray sourcesareGalacticstars.Eachspectrumisaccom- fications wehavedeterminedfromspectraintheliterature, sources, extractedfroma2"x4"aperture,arepresentedin were unabletoobserve25(mostlysouthern)unclassified 210 ofthe241B92X-raysourcesnowareclassified.We classifications for105oftheB92X-raysourceswere Figure 2.Theremainingsevenspectroscopicallyclassified objects. listed byB92andthefindingchartstodetermineastellaror from thedigitizedPalomarObservatorySkySurveyplates. obtained. Togetherwiththe105objectswhoseclassi- Large MagellanicCloudoriginfortheX-rays.Thus,new new orrevisedX-raysourceclassificationsfor93ofthem.In We madeobservationsfor99B92catalogentries,obtaining criteria is136,includingthe20high-Lobjectsconsidered 1987). Forexample,wehaveencounteredseveralappar- hemisphere (5>—25°).Opticalfindingchartsweremade in PaperI.Mostoftheseareobservablefromthenorthern to theXRB,noharmisdoneinsuchcases. spective ofoursearchforpossiblyinterestingcontributors would failtodiscoverthiserror.However,fromtheper- misclassifications forobjectswithreasonableX-raylumi- nosities fortheirclass;example,ifaSeyfert2withL= amined. Wedoruntheriskofpropagating antees thatnoexceptionalX-raysourceswillbeleftunex- classes. Forexample,normalspiralandellipticalgalaxies have X-rayluminositiesbelowafewtimes10ergssand exceeds thehighestvaluesknownforobjectsinthese axies orSeyfert2galaxiesforwhichLapproaches 12 additionalcases,weusedtheX-raysourcepositions 344 10 ergss(Halpem&Oke1987).Thisprocedureguar- 10 ergss'weremisclassifiedasanormalgalaxy,we x 1992). ForSeyfert2’s,Lisgenerallylessthanafewtimes x ~ 10ergss,respectively(Fabbiano,Kim,&Trinchieri x x Our newopticalspectraof86extragalacticB92X-ray The totalnumberofobjectsmeetingtheaboveselection © American Astronomical Society • Provided by theNASA Astrophysics Data System MORAN, HALFERN,&HELFAND -2 20 cm) inthedirectionofeachX-raysource(Starket al. source andtheGalacticabsorbingcolumn(inunitsof 10 issue isdiscussedmorefullyin§5.)TheredshiftoftheX-ray large optical/X-rayorIR/X-raypositionoffsets.Thesehave certain IR/X-raysourcechancecoincidence.Thereare29 been givena“CC?”designation.(Thechancecoincidence starburst/Seyfert compositegalaxies(§6.4),respectively.We source withtheRASSisquestionablebecauseof additional casesinwhichtheassociationofIRAS CF mayappeartheletters“CC,”whichwouldindicatea reclassified severalobjectswithournewspectra.Belowthe digging moredeeplyintotheliterature.Similarly,wehave for confirmationoftheclassificationsgiveninNEDor found tobeunusuallylargefortheX-raysourceclass.For unclassified intheB92catalogwerefoundtobeAGNsafter observed theobjectsourselves.Severaloriginally these exceptions,weeitherexaminedtheprimaryreferences accepted publishedclassifications(inNEDasof1994 galaxy clusters,narrow-lineSeyfert1galaxies(§6.2),and explicitly classifiedasstarburst(Hn)galaxiesintheliter- flag ”(CF)inthethirdcolumn(definednotetoTable 2). Opticalmorphologiesarelistedfornormalgalaxiesnot fication follows.Weobtainedclassificationsfromspectrain column. OurdeterminationoftheX-raysourceclassi- (e.g., Messier,NGC,UGC,Markarian)arefoundinthefirst September) unlessLimpliedbythereportedredshiftwas ature. TheclassificationsCl,IZw1,andCompdenote the literatureunlessnotedotherwisebya“classification 1992) aregiveninthefourthcolumnoftable.Forthree objects mayhaveinthemorewidelyreferencedcatalogs Star Normal galaxy current IRASdataforthem,listedtheX-raysourceclassi- LMC H iigalaxy Starburst/Seyfert composite. Galaxy Cluster help illuminatethechancecoincidencesinsample. fications andredshiftsobtainedfromeitherournewspectra embodied inTable2.HerewehavereevaluatedtheX-ray I Zw1 Seyfert 2galaxy Seyfert 1.8-1.9galaxy Seyfert 1-1.5galaxy QSO RASS X-raysourcepositions(listedinB92)andanynames or reportsintheUterature,andprovidedinformationto fluxes andluminositiesoftheobjects,collectedmost LINER BL Lacobject marized inTable1,includingthenumberofeachtype newly classifiedinthisstudy. the 210B92X-raysourcesclassifiedthusfar,numberof criteria fortheseobjectsto§§6.2and6.4,respectively.For x objects ofeachtyperepresentedinthesampleissum- axies. Wedeferdetaileddiscussionofourclassification Table 2isconstructedinthefollowingway.TheJ2000 Our reanalysisoftheentireB92PSC/RASSsampleis Object Type 4. X-RAY,IR,ANDOPTICALDATA B92 X-RaySourceDemography TABLE 1 Total inSampleNewlyClassified 20 21 73 15 19 13 11 19 4 7 2 5 1 27 15 15 10 17 4 0 0 0 0 8 7 2 19 96ApJS. .106 . .341M have beenshiftedtotherestframe. The verticalscalesofthespectrahavebeennormalizedtosamepeak-to-peak value. Fig. 2.—Opticalspectraofthe86newly dassifiedextragalacticX-raysourcesintheB92catalog.Thespectra, plottedasfluxperunitfrequencyinterval, © American Astronomical Society • Provided by theNASA Astrophysics Data System 4000 450050005500 60006500 Wavelength (Â) 19 96ApJS. .106 . .341M 4000 450050005500 60006500 © American Astronomical Society • Provided by theNASA Astrophysics Data System Fig. 2—Continued Wavelength (Â) 346 19 96ApJS. .106 . .341M 4000 450050005500 60006500 © American Astronomical Society • Provided by theNASA Astrophysics Data System Fig. 2—Continued Wavelength (Â) 347 19 96ApJS. .106 . .341M 4000 450050005500 60006500 © American Astronomical Society • Provided by theNASA Astrophysics Data System Wavelength (Â) Fig. 2—Continued 348 19 96ApJS. .106 . .341M © American Astronomical Society • Provided by theNASA Astrophysics Data System 349 19 96ApJS. .106 . .341M 4000 450050005500 60006500 © American Astronomical Society • Provided by theNASA Astrophysics Data System Wavelength (Â) Fig. 2-—Continued 350 19 96ApJS. .106 . .341M © American Astronomical Society • Provided by theNASA Astrophysics Data System 351 19 96ApJS. .106 . .341M 4000 450050005500 60006500 © American Astronomical Society • Provided by theNASA Astrophysics Data System Wavelength (Â) Fig. 2—Continued 352 19 96ApJS. .106 . .341M 4000 450050005500 60006500 © American Astronomical Society • Provided by theNASA Astrophysics Data System Wavelength (Â) Fig. 2—Continued 353 19 96ApJS. .106 . .341M 4000 450050005500 60006500 © American Astronomical Society • Provided by theNASA Astrophysics Data System Wavelength (Â) Fio. 2—Continued 354 19 96ApJS. .106 . .341M 4000 450050005500 60006500 © American Astronomical Society • Provided by theNASA Astrophysics Data System Wavelength (Â) Fig. 2.—Continued 355 19 96ApJS. .106 . .341M 4000 450050005500 60006500 © American Astronomical Society • Provided by theNASA Astrophysics Data System Wavelength (Â) Fig. 2.—Continued 356 19 96ApJS. .106 . .341M i I«»1 I 1L 4000 450050005500 60006500 © American Astronomical Society • Provided by theNASA Astrophysics Data System Wavelength (Â) Fig. 2.—Continued 357 19 96ApJS. .106 . .341M © American Astronomical Society • Provided by theNASA Astrophysics Data System 358 19 96ApJS. .106 . .341M © American Astronomical Society • Provided by theNASA Astrophysics Data System 359 19 96ApJS. .106 . .341M 4000 450050005500 60006500 © American Astronomical Society • Provided by theNASA Astrophysics Data System Wavelength (Â) Fig. 2.—Continued 360 19 96ApJS. .106 . .341M 4000 450050005500 60006500 © American Astronomical Society • Provided by theNASA Astrophysics Data System Wavelength (Â) Fig. 2.—Continued 361 19 96ApJS. .106 . .341M 4000 450050005500 60006500 © American Astronomical Society • Provided by theNASA Astrophysics Data System Wavelength (Â) Fig. 2.—Continued 362 19 96ApJS. .106 . .341M 4000 450050005500 60006500 © American Astronomical Society • Provided by theNASA Astrophysics Data System Wavelength (Â) Fig. 2.—Continued 363 19 96ApJS. .106 . .341M 4000 450050005500 60006500 i I»« I L © American Astronomical Society • Provided by theNASA Astrophysics Data System Wavelength (Â) Fig. 2.—Continued 364 19 96ApJS. .106 . .341M 4000 4500 © American Astronomical Society • Provided by theNASA Astrophysics Data System 5000 55006000 Wavelength (Â) Fig. 2.—Continued 365 J IL- 6500 19 96ApJS. .106 . .341M 1- 20- fied X-raysourcesremaininginthecatalog.Normalizations Catalog. The Tully distances,likelytobe moreaccurate tances werefoundinthe Tully (1988)NearbyGalaxies and q=0.Formanylow-redshift galaxies(z<0.01),dis- puted X-rayluminositiesassume H=50kms~Mpc lyzing independentlytheRASS sourcespectra.Ourcom- source inagivenclassbecause wehavenomeansforana- We havechosentoassume thesamespectrumforevery are clearlyadvantagesanddisadvantagestoeachapproach. determine thepower-lawindex.However,forweakRASS were determinedwithuseofthePSPCcountrateand the for AGNs,0.5keVthermalspectrastars,and6 366 than distances computedascz/H,assume H=75;Thus, strained index,anindexF=2.3wasassignedbyB92.There obtained. Whenthehardnessratiofityieldedapoorlycon- sources, largeuncertaintiesinthephotonindexwereoften source spectrumandtheGalacticvalueofNwereused to of itsclassification.HardnessratiosderivedfromtheRASS assumed apower-lawspectrumforeverysourceregardless Galactic neutralhydrogencolumndensity.Incontrast B92 assumed power-lawspectrawithF=2forthe31unclassH thermal spectraforobjectsclassifiedasgalaxyclusters.We H iigalaxies,power-lawspectrawithaphotonindexF=2 assumed thermalspectrawithkT=1keVfornormaland count ratesandtheirassociateduncertainties,asreported units), arelistednext.TocomputetheX-rayfluxes,we by B92.TheX-rayfluxesandluminosities,FL(incgs sources, novalueforNwasavailable;weassumed= 5 xlOcmforthese. 0 0 0 0 H x H The fifthcolumninTable2containstheRASSPSPC © American Astronomical Society • Provided by theNASA Astrophysics Data System MORAN, HALFERN,&HELFAND 1 in thecatalogordertoobtain anaccuratepictureofthe galaxies. Thus,itisimportant toidentifythecontaminants X-ray superpositionscertainly contributedtothespurious near theX-ray sourceposition,andvisually, byexamining scopically, by observing boththeIRASsource andobjects picked outchancecoincidences intwoways:spectro- X-ray andIRpropertiesof eachclassofobjects.Wehave report byB92ofaclass X-ray-luminousnormalspiral this sampleposeapotentiallyseriousproblem.Chance IR/ with theIRASfluxdensitiesinunitsofJy.Comments in cgsunits),followtheninthcolumn.F^wascomputed The far-infraredfluxesandluminosities,L(also not foundintheFSC.Thiswasusuallyaresultofless In severalcases,thePSCsourcefromB92catalogwas are likelytobemoreaccuratethanthoselistedinthePSC. IRAS fluxdensitiesfromtheFaintSourceCatalog(FSC; we havemultiplieddistancesfromtheTullycatalogby1.5 last column. bearing ontheX-raysourceclassificationaregivenin the have flaggedthesecasesandlistedtheirPSCfluxes. restrictive GalacticlatitudecutoffsusedinthePSC.We seventh columnofTable2.Wehaveprovidedthe60/¿m to beconsistentwithourassumedvalueofH. using theformulaF=1.26x10"(2.58S+S ), Moshir etal.1992)inthenextcolumn,sinceFSCfluxes FIR 0 fir60i 0 As discussedin§2andPaperI,chancecoincidences 5. CHANCECOINCIDENCESANDGALACTICSOURCES The optical/X-raysourcepositionoffsetsappearinthe o KO oo \—i ft

TABLE 2 X-Ray Data, IR Data, and X-Ray Source Classification O o O < co E X < fe a fe r* ^ £ r O G 3 £ G ai g o Ü o e s American Astronomical Society •Provided bythe NASA Astrophysics Data System CG £ Oi es O 1-t o f'- LO es CO CS LO O ^ CT> CO CN O 8S 1-1 ^ LO es G V 2 G S G O X I + CO + rH Z I 13 P§ es °9 ö co oo § gg Ö p es i—i o co o LO Q o oo es es 1^ o es ^ 1-H Tf § I O b0 I + O O LO XJ Ö 1§ o O es o> CO öS ö o es .-H .2 LO í"- es es oo es CO LO o o ^ O) 1-H i—i co a >> I 4- I + co co OL Ö o co es O -8 -u + CÖ O ü o o 13 £ J2 Tf CO .s i"H CO I O0 rf es co o ^ o es Ö CS o Oi co CS o cs co lo es 1-H Til 1—t Tf bO u o c i S-i o G fe o s fe I I + I + rH vL± Tf co O 1-H CO 22 co io CO ÇO co ^ es o> PQ Ö Tt t-H LO CS LO oó LO o" oT O ü o O co CO t-H y-l t~ p y-i Tf t-H CO t-H T}1 I + J_.± co CO o Ti« o LO CO 05 oó có Tf co o co o o Ö es tí« CO LO es co frZ'ao S3 T-H O 1-H Tf I + vL± < XJ co £3 CO lo ^ o es O rH ^ ö CG P 1-H O CS O Ö p o IV Tt 00 Tí« i-H 00 05 O o p 1-H Ti« i-H CO LO CÓ t- co oo" oS" ¡>> I I + 05 00 vL± ''V 00 co có p r'i Ti« LO es o 00 05 Tf CÓ CS i-H o o" O Tí« IV O 1-H CS Ö p O CS O 00 00 Ö Tí« o co iv 1-H Tí« IV 05 o có 05 oo es IÏ 2 II I + ü co co co fe Tí« LO CS O 00 CS 05 CO es co 05 IV tí« es CO O LO CÓ es p co" es" T-H Hi« 1-H Ti« IB ^ O P LÓ O 1-1 Tí« o C0 Tf co + es >> I + I Ti« o CD .-H co es es co CO Ö i-H Hÿ P iA LO T-H lo ^ o + I + o o o Hi« I—« Tf 05 es CS 1-H TÍ« ö fe oq Tt t-H co es co o o 05 es o LO 1-H .B + o fe I + Ö CS o Hi« CO Tí« 1-H Ti« 05 I

011844+145834 H ii 1 0.0229 0.031 6.09(-13) 66 0.752 4.54(-ll) High A0/x UGC838 CC? 4.36 0.016 1.41 (+42) 1.664 1.04(+44) 19 96ApJS. .106 . .341M < H t-4 PO U >< < Pi eô *5? -2 «3 +2 ^ ñ ^ £> S O _ G S O ^ +1 s X Co a O 3 r u, r O X £ SS o> P ^ lO Tt CO O CO T}î -Li 1-H i-H CO rH Tf American Astronomical Society •Provided bythe NASA Astrophysics Data System lO 05 1C t- rH Tt^ •-» Tf* I + b- co S 05 O oo co + 05 P ^ P °9 O rH Ö uo O rH CO 00 co CO o r-H b- CO Tt« I + I CO Tf + O 05 CO 05 Ö > OT II a LO o Î2;S co o f-H T—4«ij! s S C? SS U Ö O ^ 05 05 i-H CO B o o O b- CO OO co Ou I rH ^ co P co o rî< o «-i ^ O Ti< •—I ^ I + I + co J co O co co CO b- rH 05 LO 05 p b- rH rH OO o LO co o CO I CO CO 00rH CO iH »-H Tf CO 00 05 CO LO O á 5 o ^ rH B S 'O bO I + TO O bO JS . ^ci I + Ü 00 s LO ^ co o CN o oo LO + co co o ^ CÔ P b- LO Ö O o CO rH 05 CO >> co rH Tf o co 00 co oo co 1-H CO rH Tf I + I + 1 So Tt« O co S 9 il co rH co oo ^ co I o >> oo co 1-H o LO CÔ ^ 05 00 rH T* rH p co Ö rH CO br co o CO 05 ¿i Tjî co P o" oT rH Ti< o fe CO <0 ° -is ^ r-i CO bl CO CO r O -J rH LO 00 rH CO rH i 2 O b- 00 CO rH rH T* ^ LO 05 b- co rH rH ^ s I + I + i§ oo . s » co oo s ^ OO *H + 2 r O CO Tf P CÔ CO LO rH T* rH T* I + O O LO 05 T* + o co co CO LO co co o o Tf< + O 05 b- rH O CO CO O -u 05 LO «3 I o II o 05 CO co O o S C0 > co o o ’ oo 1 co oo OO 05 rH CO rH Ht rH Ht I + o oo Ht + 19 96ApJS. .106 . .341M < m H m O-t íó X < '.s z â O X <1 Co CO O G G r tb Ù4 r o O o B B © American Astronomical Society • Provided by theNASA Astrophysics Data System io Ö «o o es o o ^ o Ö o o> o oo es oo i—í «Ó lÓ CO Til o I CO O r-t rf o> lO O «“H CO XO T3 oo a *o es" + O 0O 0> 1-1 § II ss ^ o _L CO oo O ^ O r-t OO Tji 00 1-H r-¡ Ö OO 00 O io «-H T}< 1-H CS es o O V»^ v—^ O oó rí iO o> n* io t^- o ^ -o I + >> a I + rf O T* w CO o Ö o o OI CS ^H CS Ö ^ Oi ÎO CO 00 «O CO OO o CO o oo o xo 1-H o o Ö CS ^ >> Tf es r-H Xf oo CS CO IV vL¿ O xo OÓ 1-H > oo p co" oT Ö 05 Tf CO ü P r-H oo oT t-H Tj< r-H Til C» 00 -1* P rNÍ O »-H Ö o 00 »-H vL± 1-H CO P p xó CS oo CS r-H Tf Ö 1-H 05 o oo 00 ü ^ XO CSrV i^ cocs" 1-H 05 1-H Tt I-I rf J g £ tô 43 2 *5 93 o J2 GO Sh g .2 Ö G o B a> W as 1-H VH O IV cs oo Tf O 0 ö o 1-H o 00 7 es cs xo l'- CO o X 7 . *s ^ .2 íO V). K> c II 4J ^ o ° 00 —í oo ^ X 2 II & a^ o o ÜJ a; CO o IV ^ o 8z. ¡S o CS T-H cs oo oo CO Tf £ w tó P ro- o CO 05 o ö xo ^ ^ cs •-H o I CO O 00 ^H T* T> CÓ 05 >> I + (S II + xo co o CO O CO T? P ö o CO 1-H o cs >> cs oo rH T* Ö 1-H ^ XO 05 1-H xo 05 I + TP + s§ xo CO txj tó ö o xo 1-H CO oo 1 *o I xo co o —I T}< ö ^ 05 00 XO es cs •-h es r-H Tf oó I + <1 I + a o o o 00 O oo TJ* O + II ^ o 1-H Ö rH 05 O 05 rH Ttl 1-H cs iv oo CO 1-H ^ 1-H T* ,s I + I + CO 00 tS3 ö O Tt< cs co y-t 1-H o oo iv cs CO rH cs oó p oq IV lO CO 05 o ^ rH a I + I +

043514 - 780234 Sy 1.8 0.0612 0.343 1.05(-11) 38 0.854 4.80(-ll) 8.25 0.036 1.80(+44) 1.608 8.22(+44) h) a

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American Astronomical Society • Provided by the NASA Astrophysics Data System a

TABLE 2—Continued â co <1 x o o X < Ph Ph cö r a o a s ^ o CÖ G S g o Ü -H o CS CN Ol »-H t- CN o ^ r-H ^ i-H Tt American Astronomical Society •Provided bythe NASA Astrophysics Data System o CO 1-H CO d ^ O l>- £ <*> a I + I + cs 1 vL± CO CO r-H CO 05 Oi os O 00 i-H ^ 05 1—1 -rf SÖ I + I o CM b- 05 CO O co d O CO r-H CO rH CO r-H T}H S O 00 CM o CM co co d ^ O b- o Í5 o to Q I + TJH +

062924-054557 I Zw 1 1 0.1168 0.183 1.16(-11) 32 3.112pc 1.36(-10) 36.68 0.024 7.60(+44) 2.831pc 9.00(+45) h) a

05 X!'o co o a O 05 CSco -.g"O o « s o HDa> o o -h CO00 00IO co 1—1 CO CO 05 1-H Ht b-00 05LO coO oCS CS CiT-l OOb- rH CO CO 1-H CO Tl< b- o 00 05 P P LO t'- co co CS Ö 1-H Ö Ö

x O < CSI CM r—I CO CS CS CS CS CO CSrH T*co CS CS1-H CS1-H Htco t-H1—I HtCO CSt-H Htco es1-H r-l ^ rH T-l r-l ^ I w rX X I + I + I + J^± I ü I + I + I + J CtH ^1 cs^ es" es" b^" 05" PQ IO oq co P P b- P CS < es co 05 lô CS co CS 00 H

lO CO OO co 'cf O 05 00 CS Ht10 b-CS co00 Htcs esCO ooo COCS oco oCO o--I o05 o1-H oCS oT-H 1-H P ^H o o o Ö Ö O Ö c» CO oo ,CS 05 CS1-H COCS oo CSk oH 00rH 00b- P CS05 rH10 co05 05b- Q p öT H O 00 P ,4 CÔ Q P P . Ö “ Ö ^ P Ht Ö

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05 o05 COLO LOCO oCS c Ë co v HtiO co co 00 LO co O 03 CO CO Ht 05Ht oLO S ^ CO 00 S‘^ CS COLO iO Ht00 LO 1000 Ht co O ^ 4- ^ 74 + + I CS^ I + + PL-, o3 a> CO I? 00 o o o co P 05 O co C co p LO 05 CS oCS COCS OU ^S o coIO -ËP § -Z 1 H* o CO S-; CO r«3 ^ t- 00 X < O B o S O Ph SS ss ës o 080900-611859 Star 2 ... 0.370 1.70(-11) 56 is SAO 250131 (F5, V = 4.8)

American Astronomical Society • Provided by the NASA Astrophysics Data System a

TABLE 2—Continued Q o < co X < Ph «3 Cti ^ X E Ç r r c S § ^ 2 cö g o U o a a ÇQ CO c O o o CO CO 00 CT> o CO American Astronomical Society •Provided bythe NASA Astrophysics Data System 00 CO Oi CO r-l O CO 7 CO -*J c$ II '8 SB 05 U CM 05 t" to < co o ^ CO CM to £ -o ^ CO 4- ° s á c ^ tí X Q u co + + a Ü CO o CO CO 05 oo to ■Tf ' p ; oo CM CM to 1-H ^ Ö CM oo p CM 00 1-H TÍH 1-H CO I + co T*H O Ö 1-H TJH 1-1 CO CO r-H 1-H to 1-H CO 1-H 05 CO CM CO co rH TfH 1—H Tt< a I + CO 05 Ü Ö ° P CM CO r-H T*H + 2 p a I + , O O CO vLi o p o P CO 05 05 CM TfH Tf p 1-H ^ to 1-H 1-H tO + CM _1_ '—' o TJH + Ü PQ ^ CM P oi CO 05 O CO CO to 00 o O CM CM CO Ö CM O CM CO rH Tt co oq OO 1-H 05 tO TjH 1-H to" ^h" 1-H rH 1-H 00 CÖ I + CO CO CM Ö ^ O CM Ö O Tf rH CO CM r-H CM p OO to OÓ 05 P 1-H CO 1-H CO 05 to rH 'Tf a I I + I + Ö o b- CM CO 1-H O 1-H CO rH ^ Ht b- O to to CO b- T—I 1-Hto 1-H TÍ« a I + I + w PÍ P O oo Ht CO CO o 'V o O 1-H Ht o co 1-H i* CM >> I + I +

095155-064959 Sy 1 1 0.0146 0.181 4.19(-12) 35 0.653 4.14(-11) NGC 3035 4.26 0.020 3.90(+42) 1.607 3.86(+43) 19 96ApJS. .106 . .341M U tu < hJ 0 H c> X c O ix, co c*i ^ x E r r o a Ö £ ü s s o g ^ s ^ 05 IS] i-H 00 CS io CO ^ CO r-f CO r-H CO o io cs o CO cs »—t ^ r-H Ttf r-H American Astronomical Society •Provided bythe NASA Astrophysics Data System I CO I ^ I + I + CS V 00 11 g ^ CO r-H Ä O iO O r'v cs co 05 O II r-H 00 ö p 00 o O CO co o £ Tf CO O 00 'O 1-Î ö CO o I-H ^ rH o O r-H + o _|_ CO a >> I I + I + io O O co CO rfr S II IO i—I 00 O »“• 00 iO o 05 Ö o o Tf o r-H CO O CO o ^ 'S «-Î ö 00 ^ io cs + o a 2 II I CO I + cs + 2; §g es O H tí O co 40 05 IO o co io 00 co o CO o CO o io cs o cs o T5 1-H Tf O ^ 05 ri< + o -I- ^ >> I + I + o o cs o 00 o o o 05 05 o , io ö cs co 00 IO 00 t— T-* O rH 00 1-1 ^ Tf CO l + I Hjr r-H + NI ö CO r-H o CS co co oo o co 1-H T}1 £ I + + o TÍH o co ü ö CO 1-H co o o oq p ^ o co »-H o o l6 o" 10 co U JV tv co °g r-i ^ co CO cs CO io io P o co 05 ö O 00 tí cs o IO co 'O cs iv cb CS 00 co .2 1-H T}1 i-H O I + cs + g ^ co co ^ co CO T—H ^ io OO o TÍ1 P rs o ^ ö o ^ iv O r-H 05 r-H 001-Hi-H 1-H i-\ CO ^H 1-H ■rfl + i-H I + I + 1-H cs co o o cs o co cs 05 CO o 05 1-H Tf IV CS co 1-H + I + o o 10 gîo cs rH IS1 io io P 1-rv o co < o ^ cs^ vü J-g 'S ^ CO »-H CS 05 ^1 cs p r-H o 1-H T* cs 1 s *-• , o o c 10 1 10 IV O Tt* CO co i-H co lO Tjl io 05 o 'O ö ö o ^ 05 IO .2 rH o cs co o o 1-H H* cs I I + I + CO o io co oo co o co p , CO io 05 ^L± ö 00 cs co O TJ1 rH Ttf cs cb p IV CS rH oToo 1-H Tt rH 05 I + io

103234 + 650228 SAB(rs)bc: 0.0056 0.047 6.21(-13) 8 0.868 6.70(-ll) Tally dist = 28.7 Mpc NGC 3259 1.69 0.016 1.38(+41) 3.083 1.48(+43) a

TABLE 2—Continued â o X < CL. e<3 u O -X x CO E u* r co a> o p ^ G ü fl3 o £ £ s CO ~o m CO i~- CO CO CO P «-; O Tji CO r-i Oi Ö CO o TJ 2 z T* O CO iO io CO CO I CS »“H II ' CO I iO I + ■rf + ^ oo" ^Li 3 p t- Ö o t- CO p ™ O CO CO Tí* CO CO lO CO p co O CO . b- XO t-h CO CO r-H rH Tf Ö CO 01 lO 00 CO r-H U0 r-H ^ »-H CO + 00 r I rH I + 00 vL± vLi p ^ CO CO co o O 2 a 01 CO s co <-? ° s «o S XO tH p co" oT '■o CO 01 O 00 Oi P co 1-t ^ oo" o" o ^ *h cr> rH CO 1-H rr c I o CO I So Oi CO t'- <0 CO o 0 co O CO 00 rH CO o xO XO P XO Tf CO £ H X xÔ CO CO TJ rH Tf b- CO 00 o> xo «”H Tf a >> I + co" CO CO o CO o o CO o CO oq rH 00 oo -8 CO 7 Cö I tS] o Oi CO co CO Oi IV o Oi N» Ô l co 00 C/3 o t> i3 æ CO rH T* rH xO + £ £2 ¡I bO 0) »0 I + r-H CO + C/3 d,± o o CO CO xO rH is. 00 CO o ® XO XO Ö rH o rH CO CO co o ^ rH Tf •H TJÎ P rH xO^^h" rH >> I + C/3 2 -X Tt t- 01 p 0 Oi CO o CO CO XO CO Oi 00 Ö Oi CO P rsi CO co o co rH t— co XO 00 rH Tj* rH + CO I + I + ^h" vLi 03 O Ö o CO rH 0Ö 1H P rH :=! o S o P tri o Tr CO 00 CO o CO CO O o Oi co rH ^ o ^ TJ £ a I + CO p CO '«t CO rH rH Tf oq p IV CO CO rH 00 r-î TJÎ rH Ttf O co I I + I + I o o 00 co o ^ b- 00 " co CO 0 oo O r O CO xO o o P r-; CO o o O Oi XO rH Hÿ IV H* + CO I Oi I + I + Ht co o Oi co CO XO co IV Oi Ö o 2 p CO co rb CO rH -rtf rH rf rH I + I + XO CO PQ o XO rH OÜ O • IV CO O XO O CO Ht co rH CO rH XO rH Tt rH CO I + rt +

114209+101648 Sy 1-9 1 0.0205 0.041 8.33(—13) 39 3.089 1.83(—10) Formerly Sy 2 (Paper I); broad Ho: variable NGC 3822 3.28 0.012 1.54(+42) 6.587 3.33(+44) in 1 year. o KO oo \—i ft

TABLE 2—Continued X < cu 3 £ Z . F* r o 3 & o o c z o £ 1 CO CO o O *1 ri ^ 00 lO i—t "rj Q ^ Oi »1 CM rH O 1 n rf Ö il o 1 ; American Astronomical Society •Provided bythe NASA Astrophysics Data System I H- I + » CO o 3 Ü o cm a> > I + I CO ' o »1 + •o CM CO 00 il P ^ O Oi o CM rH r\i V' CM Q cm O iO CM o + O 4- ^ a t» II + O CM co o o co N CM ^ TJ« n n ^ Oi IV CM ^ CO CM n O a £ I + I + s o ^ ^ co oo co CM O CM 00 IV to 11 Tt< o ^ ö p ,_; CN tO O O S§ 5 o CM I- CO co ^ to iv rl í-> ^ H + o I + I + t co 1 < tí CM Ö rH O ^ O IV ^ to to OÍ rH t- O n ^ rH CM tí Ö rH CO CO to 2; Ö r—I Tf to CO -O CM IV O to rH O O Q + 2 O. >> O I + I + U Ü O Oi TD rH CM CM CO OO ^ rH Tj< C O CO CO CM CO O O TÍ 00 rH CM o U O CM CO P O rH T*< CM ^ CO CO o O CM o rH rV rH Z + 2 a I + I + I rH 'V vLi CO o rH CM C « CO rH rH ^ CO co O CO O rH tO O rH TjH p OO^V CM rH Sg S U co CO o o • co n< CO n ^ to o + CM -I- ° o* >> I + CO 5 >L± oT rH ^ co CÓ 'Cl OO CO tsi rH H* CO Ö rH T* rH So CO rH Tjt lô ^ p Oi" to" -r^ CM IV CM lO o> CM rH O co o rH ÇJ) + £ Oi co T3 tí 2; tí CM CO CO rH CO O cm rn o O CO ^ Oi CO o ■ to o rH TÍ« O 00 CM CM Ö O to -I- O, 1 CM I + + Oi co CM o ^ tO z; S ^ W CO O Í2 O tí O CO IV rH Ttf O co g «i tO rH to ^ rH Z + CO -I- ° I + I + p oq CO Oi O* CO O O CO CM O rH n h* CM . 01 CM o CM co CM Ü 0 IV CO co o o CO rH CO + r I + I + ,_H rH rH Tf O CM CM O 00 co 00 to Ö I + I +

123504-371533 Sy 2 1 0.0302 0.058 1.54(-12) 13 0.523 3.23(-ll) 5.78 0.022 6.24(+42) 1.218 1.30(+44) o KO oo \—i ft

TABLE 2—Continued Ph CÔ O £ O Ü á < C«H ^1 X CO Co 2 S <> t-i § £ O ¿3 C 6 r o p c o O G > I CO I o 1 05 «M ÿ oo T7 os O OS TP SO ^ II w pi i-H ¡z; 1-H TP o P 0O o t- oo CO CO Ü £ O OO 73 c4 oo o oTo' 1-H Tp a io I tP P + so TP 00 CT> o co 1-H Z so CO O • CM oo oo io > a I + I + Tp Æ o CM O CM i-H P rH TP I + Tp + co O TP , 00 TP CM CO S o CO ^ tí g tí pi o oo tH 00 OS 00 OS 7^ 00 _l_ CM iH co 00 so O TP OS CM 73 00 o o CM OSrH,H r >> I + I + CM CO so O CM CO J^± CM 05 rH os" oo" CM O rH Tp 00 CO os ö oo so so CM O O Tp OO Tp o "O CM SO CQ I II I + ' so OS o O CO O Tp p tí CO tP OO oo O OO rH rH TP CM OO 0O rH CO Tp 73 CM >> II I + I + I t- oo 00 00 O sO CO 1—I t''- O Tp 00 OO rH O CM OO + tP rH Tp OS l>- CO Tp rH TP rH Tp rH TP i r— I + I + — OS TP Tp O oo CO O TP rH TP I + 1 + so V tsi OS CM SO tí TP tP + +

133008-205601 QS0 1.1690 0.033 9.79(-13) 16 ...... See § 5 PKS 1327-206 CC 7.59 0.012 1.45(+46) o KO oo \—i ft

TABLE 2—Continued â X < PH O O Co cü u> <1 x « -H o ¿3 ö s r r O D c £ o X O o B B © American Astronomical Society < CO oo ^ Ci O CO . l>- ID 1-H iD -rfi Ö O ^ O CO O ID Tf OO 'B OO o CO 00 co" O 1-H iO i-H CO CS lÓ fH CO Ol rH OÖ ^ C» II i o I + o 1 Zz. £2 O So Cd ID Q ns O CO C5 00 O oo t"- O ^ 05 »-H -rji rH T* iD D o I + I + Sg IV O g II 05 ¿J 50 . 05 ID Cd oo ö o O CO CO Ht IV rH rH Ht t-H CO rH O + iD r I Ht I + Provided bythe NASA Astrophysics Data System ID rH Ht oo + W CO co o <=? r-i CO IV 50 Cd Ö O Cd O oo 00 rH rH O Cd 00 ID 05 ID 05 rH Ht I + I Ht + 00 o 00 o ¿.i Ht rH o P r-i Ht 00 CO Ö O Cd rH ^t rH r- nt V iCd 00 ID 00 Cd Ht ID CO 00 rH Ht rH Ht rH Cd rH Ht + I + o Ht 00 Cd 00 Ht 00 ¿.i 00 — Cd CO Ü rH O -1 r-iPi O Ö rH O 05 ID CO ci Ht O Ht^ «T Cd Ht rH Ht + jj iD o 3 Cd QQ ID o í ' O O Tt ÿ oo rn Cd O rH Ä O CO nt O O p Ö O Cd IV TD CO ID rH Ht rH O Ht 05 00 rH ID 05 CO O o a tp I + Ht + tS3 oo Ht Ö P rH rH CO Ö o p P rH Ht rH ID + ( £ I + Ht Ht + 00 d; J g Ö O CO OO CO 05 O ID CO 00 CO ID rH + a - a> oo «Ö ^ o O S «3 Ö .2 Pp oo Cd Cd

150853 + 681413 Sy 1.8 1 0.0582 0.041 7.18(-13) 13 0.689 4.07(-ll) 2.48 0.010 l.ll(+43) 1.456 6.29(+44) a

TABLE 2—Continued X < P-. «3 1 - !tä ^ O < Co ti ^ iii tti O â X r r ^ F! 0 CÖ c a p a a o O -H a o s iO O 05 CO f-t 00 CO o lO 05 American Astronomical Society •Provided bythe NASA Astrophysics Data System Ö O «-H -Tf + I + + 05 i—i ^ i—i CN CO Ö P O 1-H I I + I + Ö O Ô l O 05 P : CO lO CO CM lO CO o ^ t-h CO 1-H ^ + as CÖ I + .+ lO O O Tf o CO C" CM OO 1-H O CO 1-H CM CO CM 1-H Ht I I + I + r ^l± ^L¿ Ht O g o OO Ht Ö O CM 1-H 05 O Ht co p Ht LO1-H 7§ O 00 CM P "! CO 1-H Ö 1-H 1-H Ht 1-H Ht CO CM iO 05 LO CO •“H Ht a Ht Ü S O *U (j Ht CO CM o 05 CM P rr; O Ht iC CD o OO CO 1-H a 3 T3 >> CO C cc b a= a> I s I II .S O I i + I + c < x CO Ht o . o ô i J^± hh >_h JS CQ p Ht P a Ht CO O 05 Ht O CO rH O CM CO CM Ht CÓ rH Ht 1-H Ht 1-H Ht ^H Ht + i-T CO bO > SS § S §1 I + CO CM + gg co co ’T* S 05 CM O 00 CO P a CO 00 O CM o CM 1-H Ht .-H Ht rH Ht I + I + g ^ o °o 05 CO CM CM CO 1-H Ht iO 1-H CM 05 o co •-H Ht r-H Ht + f" I + I + X Ht CO CO o CM Ht b- 05 ai LO rH t'- a o «3 a co X o O 05 CO O co o a o O O’ co O CO £ ^ LO 00 CO í''' CO o 00 CM b- 05 o 00 o Ht co O o Ö rH Ht lo oo 05 1-H t- O + co I + I + CM < co (Z) tí CO LO CM CM co 00 CM CO X CO 05

161532 + 360930 Star 1 ... 0.052 5.98(-13) 5 ...... V = 10.6 CC 1.24 0.010 o KO oo \—i ft

TABLE 2—Continued X Cu CÖ o X <1 CO Co E O S O CÖ G B r r o g o B B o ^ o + o lO T—I CO -H ^ I + I + 00 co CO co CN Csl F2 01 0 00 tSJ + o CO t" i—I CO CN »—I £ I + i + co O 00 LO 00 CO CO O* 05 o vL± ^ rn Ci co CO + o co O 00 o CO 0Ó ^ °9 ^oo rH CO CN iO »-H CO co O oo o ^ co oo CN r-H T-H »—I CO Ci CO CN co O + o o 0Ó Oi X co O CO Ci rH tS) O rH TÍ» lO CO b- co cC 'C O a> + + go 1-H »—> CN CO CN Q ^ CO O 00 CO CN rH^ 1-H 0Ó iO LO CN O rH ^ <1 rH Ttf 1-1 CN o I + O O 1 Ht O to . Ci --H O 00 §g CN CO rH Tt r Ht Ci r- o Ci o rH Tt» O I + I + CN V CN rH Tt Ci 00 CO LO £ co 'V o « S I + g a» >> a I + o o bO CO o co o LO LO o CO 1-H Ö o p cn" CO rH ocT 00 go S o CN o 1-H Z O CO t- ^ LO p ^ o co 00 OO ^ Ht 4- Ö O CO r-H ^l± rH if o" oo" X CO 1-H CO 1-H Ht o co I +

174833 + 684222 I Zw 1 0.0559 0.062 1.49(—12) 30 0.544 2.98(—11) See Halpern & Oke (1987) discussion regarding Mrk 507 4.62 0.019 2.12(+43) 0.966 4.24(+44) classification a

TABLE 2—Continued co O O X X < Ph «3 pin :-t¿ ^ r o a Ö s O cô G g £ o I S O co O ^ OO Ci O co cr> es CS co Tf lO vo Ö O t^- OO t-H ^ co oo b- ^ r—< ^ American Astronomical Society •Provided bythe NASA Astrophysics Data System + I + I + cs co Ö r-î O O TF co oo co TF CO co p 00 1-H 00 t"~ Ö O CO r-1 CO rH I + I ^ + o ^ ^ £ CS X s .2 73 03 ïz ° co £ Ph PÍ d, ^ Ch g •il co OO O ^ CS Ci co O O o O t- co co CS co F- CS 'o •< iO . i—t tF i—* TF SS ^ co r c co I + ' iO I lO .t2 co TF + 00 X O co Ö O O co co O 1-H o ü Si < co 00 Ci CO lO OO 00 O CO 1-H CS co CS co cô iO 1-H TF 1-H P 1-H TF 1-H TF + O I + SS co Tj JD CS co CS co lO TF O tF CS t- O CS co OO co es oX S3 Ö O 1-H tF b- TF 1-H O 1-H TF lO p 1-H O T-H tF t-H iO + 3 &Í3 cô Tl G S O bO S -ô G .^ g TF >> I + O 00 O CS O CS co CS CS Ö IO Í— 7 a O O O s SS < co TF co co lO io P cô Ci oo Ö O C0 1-H CS CO I- CO co es d 00 p O p 1-H tF co Oi 1-H TF 1-H O O \ X I + O co I ¿ X O’ co O X 00 Ph O O ^ TF Ci O F— Ci 1-H i—t tF ,-H CO ^H tF + O 4- + O I + I + Ö p Ö co t- oo r- p I + TF +

191124-525233 ... 4 ... 0.109 3.10(-12) ... 0.610 3.67(-ll) 6.78 0.038 ... 1.337 a

TABLE 2—Continued s >< ^ O pH 1ö O fe X Co CO Cl4 Ul r r ^ s ^ o ¿3 S G O G G \ g o X £ O o American Astronomical Society •Provided bythe NASA Astrophysics Data System t- o X co O b- 1-1 10 lO + a o co vL¿ Q co Oi 00 1-H P p 00 Ö co es 1-H ^ CO rH CO co có es 0 es 10 10 co i-H ^ i-H Tf 1—1 >> I + V u co £ es co Oi o CO <1 Ö '3 7 es es <ó P Ht es 00 1—H O i-H O -*■5 «Ö ® 'o a» -iS CÔ O > a II Ht + o ^P" co" J^± ce 10 CO 00 CO Ht T3 IO co CO Q es o O Ht CS 10 10 cs Ht Ci o es co co 06 Ht p 1-H Ht 1-H Ht 1-H Ht O O I + O >¿.± 01 co 10 00 o , o Ö ’ CO 1-H b- CS es oq es p o" es .-H Ht O Ht cs es es co co es i-H b^ i-H Ht .-H Ht o S a I + J^± o ü b- 10 Ht o 00 co p ^ co 00 O Ht o 01 CS 00 o es i-î p es 10 CS co 2 § 00 cs 1-H Ht o S a Ht Ht + es Z go S o CO o Ö o . b- o Oi 00 co 00 ö es P Ht 10 co Ht OÍ I I + "es" co 00 co Ht CO C/5 S p 'cô 2 Oi Ht CS3 Oi 00 Ht Ht O 1 8 •r* COO ’“i b-1 Oi CS Ht Ö 10 00 co 00 00 10 1-H Ht i-H 10 1-H Ht "£ o a» G 0 p- (3 o N I + I + .s < go K es X 10 O b- co <© Oi Ht Ht 1-H r-1 10 p co o O 00 O Ö CO 1-H CS 10 o 00 co 1-H Ht 1-H co 1-H Ht + Oi o I Ht I + I + I o o CO r-Hi-H u co X g s o Ht Ht 00 1-H i-H CO CO CO o Ht CO o co o co O Ht 1-H Ht I Oi I + Ht +

204620-024834 Sy 1 0.0262 0.679 1.52(-11) 17 0.513 2.97(-ll) Mrk 896 4.00 0.054 4.61(+43) 1.041 9.03(+43) a

TABLE 2—Continued <1 co X Ü Ü <2 Ü P^I CÖ X < !-s £ r c o p o ce £ § ^ £ o Ü -H o S S ? CO co" CO CM O (M oi -8 o 7 CN CD American Astronomical Society •Provided bythe NASA Astrophysics Data System eô O CO CO Oi 1-t ^ 1-H CO 00 iO SI 1-H o CO 1^ CM Oi CM 00 Ö i-h O CO b- ft I + I + I 1 10 T3 O CO CO > o I + o I ^ O O b- CM ^ CO 00 CO CO Ö S CM CM iO »—H co «-I O 1-H CO CM o ^ CO CO CM i-H TΫ o : CO i-H CM rH T* CM *5 § ^ CM ^ CO Oi o cm O i_. io CM + o ir >> I + I + O O o ^ 01 CO CM CO 0 CO 1-H T}< CM CO 1-H Tf ö p CM CO CM t}< oo Ö p Oi co cm £; CM ^ O r*5 I + I + > Ht + ¿.i Ö rH 00 1-H CM CO Ht rH CM Ht rH Ht rH Tt SI Ht o CO Ö CM O O CM rH O O ; CM CO rH b- g o Oi rH g s Ht » CM P + £ fr Ht Ht CO iO + CO CM CO Ht p b^ oT SI Ö o 1-H p iO O CO 00 £ Ht + 11 Ü O CO T3 Ht OÍ p rH Ht o b- b^ o" CO o Oi Oi iO CO rH O rH Ht b- CO O Oi CO CM CO O b- CM X co ¡X o g O 1-H lO IO £ ^ -r ^ >> I + i co <1 O Ht CM CO oo b- OO IO CM CM O Ht O oo II fff X I

231340+140117 Sy 1.5 1 0.0400 0.096 2.40(-12) 9 0.886 4.96(-ll) NGC 7525 = Mrk 316 4.99 0.015 1.72(+43) 1.654 3.55(+44) 19 96ApJS. .106 . .341M American Astronomical Society •Provided bythe NASA Astrophysics Data System < H PQ J m ci U o c X < Pn CÖ !t5 ^ O fa O (S * >< <1 co fes ^ E r o £ o eô c S r o p a o É S -H O F! o 6 5 CM X oo O O CO S il CO ¿J o r-t Tî« P c4 (N Oi Ci Ö CO o iO CV> CO to CO Ö c4 oq P CO oO I + I + ¿à o iO CO CO CO O co CM O CM CM b- CO CO O ~ CO Oi CO o Ö o o CO 1-1 LO ^ CM rH ^ 00 Ci »-t CM I + I + CO tS3 ^ co" J^± Q Oi co Ö O o b- ^ CO P 1—I b- LO 1—1 i-î id CM CO r-H Tf CM .-i 00 Oi O Oi O lO 1-1 I + Q Oi OO 1-H TF CM CO 1-H LO 00 Oi CO CM 00 1-1 tF I + I, + X) 'O 43 -s U i: •s^-s t4H r g1« 3 Phg 8 gc cd o c î § ce fti^pCO 13 CXCce' 02 ' cd U O Oio (L) ^Æ c o2 ^ gbû - P , XJ ■ «»•—'43 < -en2 « £22 (•Poe ! cÆ^ i ûûë5 ! ?.S« t *PiIf lin ti cdP U ^ J2 £ ¿'SS a C ogpO x fa «3 ‘ZîP 0..2 g g !><£ 22 ^ o ■ ^ < ö (t>oP >û *12 '' « i»< ^2H ce CO=43 5 cepeci _ ^ o2 'O O . -P Ü 33 cP P 6 § TJ fa 43 co ^ ^ O S'S 8 lx ^c pp o9« Co lJ ^ T3 £5-S ? ■s ^ T3 Ö ü g ^ ^ « g! .. Co I—I g £P 2 P ce iftu O « oû^7 o 2 Ü CM fa^k dû c a « « X a, ^ cd 52 g U O .2 ü c o Ji * s * CEÍ s - g P ^ Oh CO (U 00 8 S 2 60",mayalsobemainlychance two cases,brightstarsarefoundclosetotheX-rayposition; to observe,sixhavelargeIR/X-raypositionoffsets,andin these arelikelytobechancecoincidencesaswell.Thereare, catalog withlargeoffsetsduetoerrorsintheX-raysource however, atleasttwogenuinecoincidencesintheB92 positions :NGC1068(A/x55")and6552 observation toverifythatNGC6552istheRASSsource. 0/x 106"). Inthelatterinstance,weexaminedapointedPSPC 0 On spectroscopicgrounds,wehaveidentified11chance Twenty-nine morechancecoincidencesaresuspectedon a b a bd b b b b © American Astronomical Society •Provided bythe NASAAstrophysics Data System source. 00100 +7730. 00580 +3055... 02211 +5206... 08456 +5328... 06501+ 2222.. 10213 +0644... 10113 +1736... 13273-2040. 16042+1825’. 14305 +3153°... 16137 +3618... 17109+ 7714.. 17224 +7706... 18198 +6515.. 18041+ 6950.. 19149+ 7750.. a b d c Classificationfromtheliterature. CFcatagory3inTable2;unlikely tobeRASS IC1191. NGC5672. IRAS Galaxy Non-X-Ray SourceB92IRASGalaxies TABLE 3 0.0355 Hii 0.0511 Seyfert2 0.0160 Hii 0.0223 Hii 0.1115 Seyfert2 0.0437 Hii 0.1149 Seyfert2 0.0119 Hii 0.0179 Seyfert2/LINER 0.0389 Seyfert2 0.0919 Hii 0.0678 Hii 0.0347 Hii 0.0494 Hii 0.0256 Hii 0.0592 Hii Classification /jR^liS-SELECTED X-RAYGALAXIES -2 Thus, notalllarge-offsetentriesinthecatalogcanbe emission [Wangetal.1991]aswellahighsurfacedensity lanic Cloud(knowntohaveregionsofintense,diffuseX-ray assumed tobechancecoincidences. close galaxypairs(110129—122606,110923+714247, classified X-raysourcesinvolvedoublenucleusgalaxiesor considered thenassuch.Similarly,sixspectroscopically chance coincidences;however,boththeX-rayandIRemis- of discreteX-rayandinfraredemitters)maybe,inasense, sion arelikelytocomefromtheLMC,andwehavenot cidences orifbothcomponentscontributetotheX-rayand lines. WeattributethemajorityofX-rayandIRfluxto a Seyfertnucleusorstrong-linedHitgalaxy,whileitscom- IR emission.However,ineachinstance,oneoftheobjectsis list theredshifts,classifications,andseparationsofcom- the strongestemission-linecomponentinallsixcasesand panion isanHiiorearly-typegalaxywithweakeremission panions inthe“Comments”columnofTable2. 181716 +261254).Wecannottellifthesearechancecoin- 152109 +504010,155650812902,172513584957,and cidences intheB92sampleandhavemadestrongcasesfor cidences expectedintheB92catalogwillbeidentifiedonce 29 more.Thus,itwouldappearthanthe40-50chancecoin- the classificationsarecomplete. XRB hasbeenresolvedinanyenergyband(Hasingeretal. al. 1990),eventhoughatpresentnomorethan~60%ofthe from theintegratedemissionofdiscretesources(Matheret decades ago(Giacconietal.1962),itisstillnotknownwhat (Fabian &Barcons1992,andreferencestherein).Active types ofX-ray-emittingobjectsareprimarilyresponsible gies (Stockeetal.1991;Boyle1993).However,most galaxies arethedominantcontributorsatsoftX-rayener- to explaintheshapeofobservedXRBspectrum.The AGNs donothavethecorrectbroadbandX-rayspectrum 1993). Thus,whiletheXRBwasdiscoveredmorethanthree (Hamilton &Helfand1987;BarconsFabian1990)and cantly totheXRB.FluctuationanalysisofdeepEinstein radio-loud quasars,arefartooraretocontributesignifi- AGNs thatdohaveapproximatelythecorrectspectrum, exceeds 1000deg.Thus,inadditiontospectralcon- surface densityofsourcesmakinguptheXRBgreatly ROS AT(Hasingeretal.1993)imageshasindicatedthatthe ment. Ithasbeensuggestedthatanentirelynewclassof XRB mustalsosatisfythisstrictsurfacedensityrequire- straints, theclassofobjectsthatexplainsorigin XRB (Fabian&Barcons1992).Amongknownclassesof X-ray sourcesmaybeneededtosolvetheproblemof X-ray sources,starburstgalaxies(Griffiths&Padovani ising candidatesfortheoriginofXRB.Bothtypes Comastri etal.1995)currentlyrepresentthemostprom- work oftheunifiedmodelfor Seyfertgalaxies,areableto (1994) andComastrietal.(1995), which,withintheframe- most successfulmodelstodate arethoseofMadauetal. objects areknowntobeluminous infraredemitters.The number countsinthehardand softX-raybands.However, produce theXRBspectrum and observedX-raysource 1990) andobscuredSeyfertgalaxies(Madauetal.1994; these modelsassumeseveralspecific detailsregardingthe 6. SUBCLASSESOFX-RAY—ANDIR-EMITTINGGALAXIES Four sourceswithintheboundariesofLargeMagel- In summary,wehavefirmlyidentified18chancecoin- The cosmicX-raybackground(XRB)isthoughttoresult AND THEX-RAYBACKGROUND 385 19 96ApJS. .106 . .341M , ■-•.: : ■-'.."» -i ■^c-±-x © American Astronomical Society •P^vided bythe NASAAstrophysics Data System ■ '.•Í- * •'*.;/■ 010051+311141 -¿-¿-¿.a: 003329+400619 19 96ApJS. .106 . .341M © American Astronomical Society •Provide^ J^ythe NASAAstrophysics Data System 080900-611859 084919+531805 102402+062946 Fig. 3.—Continued 080901-191402 101403+172245 19 96ApJS. .106 . .341M © American Astronomical Society •Provided bythe NASAAstrophysics Data System 143234+313847 110912-300106 161532+360930 133008-205601 19 96ApJS. .106 . .341M 43-1 43-1 42-1 43_1 431_ (1983) hadsingledoutMrk 316 foranextensivediscussion (001009 —044200,L=1.6x10ergss),which was fication, remarkingthatthis objectdeservesfurtherinvesti- cataloged asaSeyfert2(Hewitt&Burbidge1991),isclearly much ofthediscussioninterestingsubclassesin know ifthebroad-line strengthshaveincreased, orifthe gation. Intheend,sheretained itinthestarburstsample, relative strengthsofitsbroad- andnarrow-linecomponents. a Seyfert1.AndMrk316(231340+140117,L= 1.7 also reclassifiedtwoMarkariangalaxiesastype1Seyferts 045602-753233 (=IRAS04575-7537),comesfrom i.e., thosewithspectralcharacteristicstypicalofoptically fications. Suchclassificationshaveheterogeneousorigins principally because the[Nn]/Haratiois small. Wedonot of therelativemeritsaSeyfert versusastarburstclassi- Spectra ofbothobjectsare displayed inFigure2.Balzano that werepreviouslythoughttobeotherwise.Mrk 937 high X-rayluminosity(L=1x10ergss).Wehave spectrum, which,ifpresent,wouldexplainthereasonfor its broad HacomponentissuggestedinthedeGrijpet al. both casesitisbasedonalowsignal-to-noisespectrum. A have beenidentified.Bycomparison,only19ofthe210 selected AGNs,aretype1Seyferts.Inall,119AGNs here. uniformly aswehaveexaminedourownspectra.Therefore, moderate-resolution spectroscopy,haverevealedobjects have reliedsolelyonpublishedreportsforopticalclassi- sources havebeenexamined(e.g.,Greenetal.1992;B92) lend importantinsighttotheseissues. luminosity function,inadditiontotheuniversalityofAGN distribution ofintrinsicabsorptioninAGNsandtheAGN Kirhakos &Steiner(1990)anddeGrijpetal.(1992),but in offsets (62"and67").Theclassificationforthethird, be chancecoincidencesbasedontheirlargeoptical/X-ray outliers, 181353+570456and182121551546(L=2 times 10ergss;Halpern&Oke1987).Twoofthe observed forSeyfert2’sinthepast(i.e.,Llessthanafew the singlenarrow-lineradiogalaxy).Allbutthreeof objects classifiedaretype2Seyfertgalaxies(thisincludes B92 sampleisbasedonthenewdatawehavepresented were notabletoscrutinizepublishedspectraofobjectsas these deserveacloserlookinthecontextofXRB.We AGNs inthesample,aswellsomenormalgalaxies.All important, features. with awiderangeofproperties,someverysubtle.Thus, finds thatobjectstendtobeplacedinbroadlydefinedcate- also sensitivitytothepossibilitythattheycontainweak,yet sample requiresnotonlyhigh-qualityspectraldata,but search forpossiblenewcontributorstotheXRBinB92 gories. OurpreviousinvestigationsofIR-selectedX-ray and canbelimitedintheirprecision.Furthermore,one ationally. Studyofinfrared-andX-ray-selectedobjectsmay unification, allofwhichhaveyettobeconfirmedobserv- Seyfert 2’shaveX-rayluminositiesconsistentwiththose objects areAGNs.Thereare,however,awidevarietyof of objectsinthissampleinfrared-andX-ray-selected sources (PaperI;Moranetal.1996a),involvinghigh-S/N, x x x x x x 10ergss)isaSeyfert1.5galaxy,onthebasisof the x 10ergss"and3s,respectively),may Most oftheclassicalSeyfertgalaxiesinB92catalog, It isclearfromexaminationofTable1thatthemajority Previous studiesinwhichlargenumbersofIR/X-ray 6.1. ClassicalandNonclassicalSeyfertGalaxies © American Astronomical Society • Provided by theNASA Astrophysics Data System IRAS-SELECTED X-RAYGALAXIES -1 42-1 43-145 4243-1 -1 identified 15new ones.TheX-rayluminosities oftheB92 addition tofive previouslyclassifiedexamples, wehave Their abundance,however, issomewhatremarkable:in surprising thatIZw1objects appearintheB92catalog. & Oke1987). class (Stephens1989).Theseobjectsarealsorapidlyvari- Brandt etal.1994)andluminous infraredemitters(Halpern able X-raysources(Remillard etal.1991;Boiler1993; efficient meansforfindingthem;indeed,asubstantialfrac- tion ofX-ray-selectedAGNsturnouttobemembers this Halpern &Oke(1984)tosuggestthatX-rayselectionis an nosities ofIZw1-typeobjects,withLrangingfrom weak, butitappearsthatFenemissionisalwayspresent at some levelinnarrow-lineSeyfert1’s.ThehighX-raylumi- the totalemission-lineflux.Inothercases,Fenlines are complexes, mostprominentlyinthe4500-4680Â and (e.g., F([0m])/F(H/?)<3],(3)high-ionizationlinesfound in classicalSeyfertl’sand(4)narrowFenemission-line (FWHM <2000kms),(2)weakforbidden-lineemission characterized by(1)narrowforbiddenandpermittedemis- 5105-5395 Âwavelengthranges(Osterbrock&Pogge sion linesofapproximatelyequalvelocitywidth axies, theprototypeofwhichisIZw1(Phillips1976),are hard X-rayproperties. sic absorptionandshould,therefore,possessinteresting 1985). TheFenemissioncaninsomeinstancesdominate (narrow HaismostlyabsorbedandnarrowH/?not In alllikelihood,theseobjectshavelargeamountsofintrin- observed atall)andanunusualbroadHaemissionfeature. L =6x10ergss),whichhasveryweaknarrowlines ing exampleisthatof124144+350343(=NGC4619; x ~10 ergsstoinexcessof10,prompted versions oftheseheavilyreddenedobjects.Themoststrik- yet veryweakemissionlines(e.g.,014526—034934and tional Seyfertgalaxies,withcomparableX-rayluminosities soft X-raysources(L=10-10ergss).Afewaddi- axies areheavilyreddened;nonetheless,theyluminous 083539 —040543,and095155064959),Itwouldappear 043812 -104721,044351+285838,064011-255341, that boththebroad-andnarrow-lineregionsinthesegal- narrow Hßemissionaswell(e.g.,040902+153048, evidence forbroadHßemissionandhaveonlyweak thousand kmsrelativetothenarrowHacomponent.All complex structurewithanintensitypeakshiftedbyseveral emission-line propertiesordistinctlynonclassicalcharac- 101654 +732355=NGC3147),couldrepresentextreme the galaxieswiththeseattributesexhibitlittleorno 080026+101302 inFig.2),afewothershavepeculiar teristics. Inseveralobjects,thebroadHalineshows fluxes (Stockeetal.1991). most prevalentextragalacticsourcesathighsoftX-ray x previous resultsindicatingthatbroad-lineAGNsarethe even withtheadditionalconditionofIRselection, predominance ofSeyfertl’sinthissampleisconsistent, their starlight-dominatedcontinuuaweresubtracted.The original spectrumwassimplyofinsufficientqualitytorec- x Seyfert 2’swouldprobablyrevealbroadHacomponentsif ognize them.Afewotherobjectswehaveclassifiedas 1 orintermediate-typespectra(e.g.,123137—475851and Given theirknownX-ray and IRproperties,itisnot The spectraoftheso-callednarrow-lineSeyfert1gal- While mostoftheB92Seyfertgalaxieshaveclassicaltype 6.2. Narrow-LineSeyfert1Galaxies 389 19 96ApJS. .106 . .341M 4 -1 44_146 _145- 42 fact, bestrecognizedbytheapparentdipsincontinuum 2) quasarknowntodate,averyspecialdistinction. Our 20181—2244 makeitthemostluminousnarrow-line(type they causenear4780Âand5080Â.Recently,Elizalde & ence ofweakFenemission.Amongall20B92IZw 1 224805—172837, theFenlinesarenotobviousandare, in such as202103-223434(=IRAS20181-2244) and interpretation ofIRAS20181—2244 asamemberofthe comparison totheotherIZw Ts.Therefore,wefavorthe more, Table4indicatesthattheemission-linewidths and nosity andisthefourthmostluminousIRsource.Further- higher S/Nspectrum,however,indicatesclearlythepres- Steiner (1994)reportedthatthepropertiesofIRAS such as120226-012948and121547+544220.Inothers, spectra showverystrong,resolvedFencomponent^ They arearranged,fromtoplefttobottomright,inorder I Zw1class,withwhichitsIR, optical,andX-rayproperties objects, IRAS20181—2244ranksjustfifthinX-raylumi- are avarietyofFenlinestrengthsrelativetoHß.Some of decreasing[Om]/H/?peakintensityratio.There normalized suchthattheheightofH/?issameforeach. region, Thespectrahavebeencontinuumsubtractedand line Seyfertl’sinTable4anddisplayFigureoptical we listemission-linemeasurementsofall20B92narrow- exhibit arangeofemission-lineproperties.Toillustratethis, ergs s. highlighted, which isastar. Fe iistrengthofIRAS20181—2244 arenotextremein spectra ofthe15newexamples,isolating[Om],Hß nosities, whichrangefrom1x10ergssto ergs sto2x10,asaretheirfar-infraredlumi- identifies 20181—2244. Thegalaxyistheobject~10" northeastoftheone narrow-line Seyfertl’sareveryhigh,rangingfrom1x10 390 41 ThefindingchartpublishedbyElizalde &Steiner(1994)incorrectly As anyotherclassofSeyfertgalaxies,theIZw1objects 202103-223434. 224239 +294337 205457-231834. 095218-013659 234338 +024453. 224805-172837. 062924+054557. 052955 +443453. 050022 +091659. 044428 +122111. 03442 +401421.. 174833 +684222 170330+454042. 144207 +352624 163322+471908. 132519-382421 121547 +544220. 120266-012948. 110923 +714247. 100508 +842033. d-1 a b2_ Linewidthsinunitsofkms;instrumentalbroadeningremoved. PertainstotheFenlinecomplexcenteredat4570Â. * Boileretal.1993;Boroson&Green1992;Goodrich1989;OsterbockPogge1985. * EquivalentwidthsinunitsofÂ. Emission-lineflux,relativetoHß.FovHß,themeasuredlinefluxislisted,inunitsofergscm"s^ © American Astronomical Society • Provided by theNASA Astrophysics Data System (Ark 564)* (Mrk 507)*. (Mrk 478)*... (IRAS 13224- (Mrk 12399)* Object 3809)* MORAN, HALFERN,&HELFAND I Zw1Objects:Emission-LineMeasurements h 4.62E- 2.21E-15 2.95E-14 2.75E-14 3.50E-14 2.11E-14 8.23E-15 1.11E-14 1.04E-14 7.61E-14 1.51E- 1.28E-14 1.66E-13 1.60E-13 1.93E-14 1.96E-14 1.10E-14 F/F(Uß) 14 14 Hß A4861 cdh 114.8 49.0 43.8 26.0 41.4 51.9 35.8 26.6 64.0 23.0 37.3 30.8 22.4 57.0 W FWHMF/F(Hß) 38.2 74.6 14.6 19.0 9.0 9.9 TABLE 4 imposed byfluctuation analysisofdeepX-ray images.Fur- could potentially satisfythesurfacedensity requirement will beusefulformoredetailedstudiesoftheseunusual emission. Thelargenumberofsuchobjectsdiscoveredhere because theyareknownX-ray emittersandbecausethey al. 1992).Starburstsareparticularly attractiveinthisregard Griffiths &Padovani1990; Raphael!etal.1991;David the XRB(e.g.,Bookbinderet al.1980;Stewartet1982; star-forming galaxies.Ithas beensuggestedfrequentlythat information abouttheoverallpropertiesoftheirbroadband (F »2;Remillardetal.1991).Observationsofother cates thattheir2-10keVX-rayspectraarealsofairlysteep starburst galaxiesmightmake animportantcontributionto Seyfert galaxies. narrow-line Seyfert1’sbyASCAwilladdmuchneeded shown tobeextremelysteep(F»2-4;Brandtetal.1994). What littleisknownabouttheirhardX-raypropertiesindi- XRB? Probablynot,astheirsoftX-rayspectrahavebeen represent apreviouslyunderestimatedcomponentofthe very luminousX-raysources.DotheIZw1-typeobjects in thespectraofclassicalSeyfert1.9nuclei. e.g., 043442+401421and052955443453,appeartohave additional weak,broadHawings,similartothoseobserved (044428 +122111and062924-054557aregoodexamples). more nearlyLorentzian,ratherthanGaussian,profiles,as stand thisclassofluminous,narrow-lineactivegalaxies. are entirelyconsistent,andweemphasizetheneedtounder- but onHaaswell.Interestingly,afewoftheIZw1objects, evidenced bytheircuspedpeaksandbroadwings Such profilesappearnotonlyontheHßand[Om]lines I Zw1-typeobjectshavesymmetricemissionlineswith 1570 1450 1120 1500 1220 1670 970 490 720 965 810 580 760 650 780 630 910 780 This studybeganinitiallyasasearchforX-ray-luminous 700 690 As mentionedabove,allthenarrow-lineSeyfertTsare Inspection ofFigure4indicatesthatmanythe 6.3. X-Ray-LuminousStarburstGalaxies 0.73 0.73 0.25 0.60 3.14 0.91 0.96 0.59 0.77 0.41 1.89 0.82 0.57 1.05 1.10 1.86 1.22 1.40 1.45 1.63 [O in]>15007 c 165.7 166.7 65.2 21.0 22.5 56.6 33.5 23.0 23.1 16.7 19.0 10.0 W 36.1 62.4 14.5 15.2 10.5 dh FWHM F/F(Hß) 1390 1010 1310 1150 670 750 250 470 460 550 330 650 720 930 710 440 370 11 4.05 0.85 0.70 0.68 2.44 0.64 0.61 3.26 2.36 1.97 1.01 1.26 1.21 1.46 1.10 1.51 1.22 Fe uA4570 Vol. 106 c 25.2 35.8 38.1 35.5 35.7 26.8 43.4 42.4 51.3 76.0 47.6 32.3 38.4 48.3 56.0 44.8 48.0 73.2 34.8 84.2 W 19 96ApJS. .106 . .341M 3 order ofdecreasing[Om]/Hj9peakintensityratio. emission-line propertiesintheseobjects.Thespectrahavebeennormalized tothesameHßpeakintensityandarearranged,fromtopleftbottomright,in evolution must besteeperthan~(1+z) ifstarburstsare evolve suitably, Lonsdale&Harmon(1991) reportthatthis mainly byhigh-massX-ray binaries. Buttocontributesig- nificantly toeventhesoft XRB, starburstgalaxiesmust the XRBspectrumiftheir X-rayemissionisproduced star-forming galaxiescould be responsiblefortheshapeof thermore, Griffiths&Padovani (1990)haveproposedthat No. 2,1996 Fig. 4.—Continuum-subtractedHß,[Om]spectraofthe15newnarrow-line Seyfert1galaxiesdiscoveredintheB92sample,illustratingvarietyof © American Astronomical Society • Provided by theNASA Astrophysics Data System 050022+091659 062924-054557 234338+024453 202103-223434 163322+471908 100508+842033 170330+454042 4500 5000 IRAS-SELECTED X-RAYGALAXIES 5500 4500 Wavelength (Â) (Fruscione &Griffiths1991), detectionofhigh-Lstar- nosity evolution intheseobjects. bursts couldbetakenasencouraging evidenceforlumi- luminosity hasbeenestablished inX-ray-selectedsamples While thepresenceofstar-forming galaxiesofnormalX-ray to representanimportantcomponent oftheXRBat2keV. x It appearedat firstthatthisPSC/RASS sample did,in 5000 5500 • 120226-012948 043442+401421 044428+122111 052955+443453 205457-231834 224805-172837 121547+544220 110923+714247 391 19 96ApJS. .106 . .341M 42 _1 42-1 1 42 421 42-1 41-1 41-1 42_1 42-1 X-ray variabilityand high X-rayluminosityof the B92catalog withL=6x10ergs s.Basedon just 8".Thesouthwesterncompanioniswithoutquestionan total contributionstarbursts arelikelytomaketheXRB. X-ray luminositiessubstantially higherthan10ergss. ergs s“allpossessSeyfertopticalspectra,castingfurther of starburstgalaxiesareneeded toconstraindirectlythe Ultimately, measurementsof thebroadbandX-rayspectra doubt ontheexistenceofanystar-forminggalaxieswith in theEinsteinMedium-sensitivitySurveywithL> 10 recently shownthatthefourambiguouslyclassifiedgalaxies remains unproven.Halpem,Helfand,&Moran(1995)have as inthisstudy,theexistenceofhigh-Lstarburstgalaxies weaker (<310ergssinthesample, non-AGN spirals(Fabbiano1989).Theremaybeasmany axies. galaxies isidentifiedsecurelyasanX-raysource(PaperI). careful opticalspectroscopyandreviewoftheliteraturefor x [O i]¿6300)arerequiredtoclassifythisobjectaccurately. nosity isactuallymuchlowerthanthatreportedfromthe Our subsequentASCAobservationofthisobject,NGC fact, containhigh-Lnormalspiralgalaxies(B92).However, RASS. Nonetheless,theremainderofB92sampleisan unrecognized AGNsandthatonlyoneofthefournonactive 3256 (Moranetal.1996b),indicatesthatitsX-raylumi- 392 x x 17 ofthe20candidatesrevealedthat13arepreviously x 0 x x x 10ergss),asanHngalaxypair.Thetwocom- Boiler, Fink,&Schaeidt(1994) havereportedthestrong We havealsoidentifiedafewpotentiallyluminousX-ray Most oftheB92HngalaxiesclassifiedtodatehaveX-ray © American Astronomical Society • Provided by theNASA Astrophysics Data System MORAN, HALFERN,&HELFAND -1 -1 -1 tinct regions. In §6.4.2,weaddressthepossibility thatthe although theemissionassociated withthestarburstand appearance oftheirspectra bydrowningouttheAGN, Seyfert components undoubtedlyarises in physicallydis- H iiregionsintheseobjects havecausedthecomposite improbable thatbrightemission linesfromextranuclear isolated thenuclearlightin mostofthecomposites(six the sevenhaveredshiftsless than0.04).Therefore,itis for anactivenucleus.Thesmallapertureusedtoobtain the spectra presentedinFigure2(2"x4")ensuresthatwehave galaxy spectraindicatethattheyarestarbursts,thebroad Thus, whilethegrosscharacteristicsofcomposite late ontheirtruenature. examine thecharacteristicsof“composites”andspecu- [O m]andHalinesareunderstoodmosteasilyasevidence show evidenceforaweak,broadcomponentoftheHaline. trum, forbiddenorpermitted.Severalofthecomposites also significantly broaderthanallothernarrowlinesinthespec- these galaxies,arefarfromobvious.Inthissection,we well. Thephysicalreasonsbehindthecompositespectra, of thecompositesisthattheir[Om]¿¿4959,5007lines are another featureofHngalaxies.Thedefiningcharacteristic and thereconciliationofopticalX-rayproperties sion linesthatarequitenarrow(FWHM<300kms ), ous starformation,butverysubtleSeyfertsignaturesas X-ray luminositiestypicalofbroad-lineAGNs.Detailed lowing section. diagrams (Veilleux&Osterbrock1987)orfirmlyamongthe lated byHngalaxiesandSeyfertonflux-ratio analysis oftheirspectrarevealsnotonlyevidenceforvigor- “ starburst/Seyfertcomposite”galaxiesdiscussedinthefol- fication ofIRAS15564+6359wasfaulty,thisobjectmust H iigalaxies.Inaddition,mostofthecompositeshaveemis- either ontheboundarybetweenregionsordinarilypopu- spectra dominatedbythecharacteristicsofstarbursts,have low-redshift (z»0.02-0.12)galaxieswhich,despiteoptical not beconfusedwiththenewclassofX-ray-bright must harboranAGN,butbecausetheirHnspectralclassi- The emission-linefluxratiosofthesegalaxiesplacethem sources intheB92catalogisacollectionofsevenenigmatic the compositespectra,indicateastarburstclassification. 6. Boileretal.(1994)didreasonthatIRAS15564+6359 FWHM andcontains55%ofthelineflux.Thus,true the broadcomponenthasavelocitywidthof1700kms two-component GaussianfittotheHßlineindicatesthat [O ni]/H/?fluxratio,usingjustthenarrowHßcmponent,is properties ofIRAS15564+6359arenotsoremarkable.A as broadwingsontheHaandH/?lines,clearlyjustifyinga high-ionization lines([Nem]¿3869andHen¿4686)aswell F(Ha) =0.032,F([Sn])/F(Ha)0.25],wehavedetected Seyfert 1.8classification.Giventhisclassification,theX-ray s) andthelow-ionizationlinesareweak[e.g.,F([0i])/ Although theemissionlinesarefairlynarrow(340-360km making itsX-raypropertiesunique.However,ourhigher resolution spectrumrevealsaverydifferentpicture. cluded that,optically,thisobjectisatypicalHngalaxy, measured emission-linefluxratios,Boileretal.(1994)con- The mostremarkablefindinourinvestigationofX-ray Most nebularemission-linediagnostics,whenappliedto 6.4. Starburst/SeyfertCompositeGalaxies 6.4.1. DescriptionoftheClass Vol. 106 19 96ApJS. .106 . .341M 42_143- -1 -1 correct X-raysourceidentifications. composites (A<30"),consistentwithallofthemhaving most oftheirintenseX-rayemission.Table2indicatesthat burst component,theSeyfertcomponentisresponsiblefor evidence forhigh-LstarburstselsewhereintheB92 the optical/X-raypositionoffsetsaresmallforallof posites areinfluencedheavily(ifnotdominated)bythestar- interpretation isthatwhiletheopticalspectraofcom- catalog, wedonotbelievethatthecompositesareexcep- Seyfert nuclei(seeFilippenko&Sargent1985).Instead,our tionally luminousHhgalaxiesthathappentohostdwarf their opticalspectra.Thus,giventhelackofcompelling “ normal”X-rayluminositiesexhibitcompositefeaturesin lengths byfactorsof—5-100.Furthermore,nonethe widths. Inallcases,FWHM([0m]25007)>FWHM(HjS) H iigalaxieswehaveobservedintheB92samplewith brightest starburstsobservedpreviouslyatX-raywave- and lowerluminositySeyfertl’s,exceedthoseofthe These luminositiesaretypicalforbrightSeyfert2galaxies cases. contain lessfluxthanthenarrowcomponentsinallfour we havealsomeasuredthewidthsofunabsorbedemission measured tobebroaderthanHßsimplybecauseis variety ofproportions.Table5listsourmeasurements ties. ThestarburstandSeyfertcomponentsappearina shown inFigure5,illustratesclearlythecompositenature posite spectra. strength ofthenuclearstarburstisresponsibleforcom- L rangesfrom1.5x10ergssto5. the sevencompositespectra.ThebroadcomponentsofHa with widthsof2500-3600kmsFWHM,appearinfour lines havewidthscomparabletothatofH/J.BroadHalines, lines representingawiderangeinionization;theseother peeking outofasuperimposedstellarabsorptionfeature, by atleast~100kms.Tobecertainthat[Om]isnot the compositegalaxyemission-linefluxesandvelocity of theseobjectsandtherangetheiremission-lineproper- No. 2,1996 0/x x e x 044148 -011821. 013424-154934. 011013 +501027. 003413-212619 . 200751 +593814. 200752-110834 . 101403 +172245. e d c 2 ai b The keytothecompositesistheirintenseX-rayemission: A closerlookattheH/?andHaspectralregions,as Possibleweak,broad Hacomponentpresent. Instrumentalbroadening removed. Emission-lineflux,relativetoHß. ForHß,themeasuredlinefluxislisted,inunitsofergss“L Linunitsofergss~. Equivalentwidthexcludesbroad Ha component,ifpresent. x Object © American Astronomical Society • Provided by theNASA Astrophysics Data System 0.0374 0.0304 0.1149 0.0289 0.0199 0.0237 0.0268 a log L x 42.91 43.08 43.70 42.90 42.25 42.61 43.20 Starburst/Seyfert CompositeGalaxies:Emission-LineMeasurements b W(H200Â.Wemustconclude,therefore,that Four galaxieswithsimilarcompositeopticalspectra,two A naturalfirststeptothedeterminationofnature 297 158 104 105 199 130 159 c 6.4.2. SpeculatingontheNatureofComposites [Flux/F(H/?)] /VelocityWidth(kms^ 0.88 2.86 2.51 0.99 3.00 1.24 406 1.20 457 262 580 231 307 317 0.24 0.34 0.28 0.34 0.17 0.14 4.66 7.61 6.98 4.93 6.00 5.16 5.57 312 200 173 107 133 167 156 Ha 2500 3600 2650 3130 5.92 5.94 3.45 3.72 4.29 5.48 2.80 3.07 2.96 3.07 2.23 312 200 137 197 140 152 186 2.35 1.95 1.55 1.70 1.00 1.09 1.06 304 229 148 131 197 175 161 393 19 96ApJS. .106 . .341M other narrowlines,aweak,broadHa componentisevidentinjustfourofthesevenobjects. Fig. 5.—DetailoftheHßandHa regions ofthe“starburst/Seyfertcomposite”objectspectra.Whilein eachcasethe[Om]linesarebroaderthanall © American Astronomical Society • Provided by theNASA Astrophysics Data System Wavelength (Â) 19 96ApJS. .106 . .341M -2 24 25 2223-2 the sampleremains unclassifiedatthistime, wepresentin relationship betweentheinfrared andX-raypropertiesof the variousclasses ofobjectrepresented. Although 13%of surveys, wouldallowusto examine,withoutbias,the The completelyidentifiedsample, drawnfromtwoall-sky more prevalentatearlierepochs,theycouldmake an objects detectedatbothX-ray andinfraredwavelengths. important contributiontothehardXRB.Broadband energies (Fabianetal.1990).Thus,thecompositesmay component present,flatteningthespectrumathigherX-ray objects. will determinedirectlythehardX-raypropertiesofthese cm), theremightbeastrongComptonreflectionspectral instead, thecolumndensitieswereveryhigh(i.e.,10-10 effects ontheX-rayspectraofthesegalaxies.Ifcolumn ASCA observations,scheduledfortwoofthecomposites, prove tobestronghardX-raysources.Ifso,andifthey are through it,resultinginahardobservedX-rayspectrum.If, density oftheobscuringmaterialwerenottoohigh(i.e., AGN. Heavyobscuration,however,wouldhaveprofound fraction oftheintrinsicopticalandsoftX-rayfluxfrom covering modelsforotherSeyfertgalaxies(Matsuokaetal. In eitherscenario,wewouldexpecttoobservejustasmall tions (approachingunity)thanthoserequiredinpartial radiation andsoftX-rays)withmuchhighercoveringfrac- mostly hiddenbydenseclouds(opticallythicktovisible Alternatively, itmaybethatweareactuallyviewingthe broad polarizedemissionlinesofaburiedAGNinthiscase. be polarized.Spectropolarimetrywouldreadilyrevealthe via scattering(eitherbyelectronsordust)andwouldthus from atotallyobscuredSeyfertcomponentwouldreachus 7. COMPARISONOFX-RAYANDINFRAREDLUMINOSITIES Seyfert nucleiinthecompositesdirectly,butthattheyare partially obscured,or(2)theopeningangleinmaterial 10-10 cm),hardX-raysmightbetransmitted that inotherhiddenSeyfertgalaxies.Someoftheradiation obscuring theirnucleimustbeconsiderablysmallerthan hidden AGNsdo,(1)theirnarrow-lineregionsmustalsobe optically asSeyfert2galaxiespreviouslydiscovered However, toexplainwhythecompositesdonotappear popular modeldescribedbyAntonucci&Miller(1985). 1990). X-rayvariabilitywouldbeagoodtestforthismodel, axies couldbetotallyhiddenfromourview,followingthe ties ofthecomposites.First,Seyfertnucleiinthesegal- ites isilluminatedbytheionizingcontinuumthanina emission lines.Itmaybethatmuchlessgasinthecompos- the key,oneoftwoscenariosislikelytoexplainproper- typical AGN,resultinginopticallyweakbutX-ray-bright X-ray fluxfromtheSeyfertnucleusaswellbroad Seyfert components.If,ontheotherhand,obscurationis sources, sinceanyobscurationshoulddiminishthesoft galaxy spectraisthattheSeyfertcomponentsarelargely understand whytheseobjectsaresuchluminoussoftX-ray obscuration picture.Itremainsachallenge,however,to ally higherFIRluminositiesofthecomposites,comparedto obscured andappear,therefore,opticallyweak.Thegener- equivalent widthsisobserved,butnearlyallfallbetween B92 AGNswithsimilarX-rayluminosities(§7),supportthe appear tobecapableofoverpoweringanopticallytypical Seyfert nucleus. 100-200 Â.Thus,thestarburstsincompositesdonot The B92catalogconstitutes thelargestsinglesampleof The moststraightforwardinterpretationofthecomposite © American Astronomical Society • Provided by theNASA Astrophysics Data System IRAS-SELECTED X-RAYGALAXIES 12 a sampleof IR- andX-ray-selectedsources. Thishas program toobtain accuratespectroscopic classificationsof cosmic X-raybackground,we havecarriedoutanextensive luminous infraredsources, contribute significantlytothe obscured Seyfertgalaxies,both ofwhichareknowntobe eight non-QSOsthatare“ultraluminous”far-infrared sources (L^>10L),sevenareintheIZw1class. is trueforthenarrow-lineSeyfert1galaxies.Infact,of the nosities thanmembersoftheseothertwoclasses.Thesame luminosity, thecompositestendtohavehigherFIRlumi- lower luminositySeyfert1-1.5galaxiesatagivenX-ray mixing insteadwiththeSeyfert1.8-1.9galaxiesand the avoid theregionoccupiedbynormalandHngalaxies, manner. Itisimportanttonotethelocationof the starburst/Seyfert compositesonFigure6.Theyclearly their properties.Misclassificationsmaybeexposedin this instantly, whichmightmotivatefurtherinvestigationinto evaluating theclassificationofotherobjectsinthissample. classes representedmayserveasausefuldiagnosticfor vary withpositionontheskyduetowayROSAT For instance,extrememembersinagivenclas^arevisible & Berg1983).However,thefluxlimitsofB92catalog ence orlackoftruecorrelations,withthepropertreatment of upperlimitsinacomplete,flux-hmitedsample(Feigelson sample. Suchaneffectcanberemoved,revealingthepres- 0 lations inFigure6. tangle redshifteffectsfromtheapparentLx/L^rcorre- which resultsfromtheflux-limitednatureofB92 correlations betweenthetwoquantitiesfordifferenttypesof obtaining X-rayupperlimits.Thus,itisimpossibletodisen- we havenoaccesstotheRASSand,therefore,meansof objects. Unfortunately,thisispartiallyaredshifteffect and IRASskysurveyswerecarriedout.Moreimportantly, source coincidences,GalacticandLMCsources,the Figure 6contains168points.Thegraphappearstoindicate tentatively classified(CC?)entriesinthecatalog;thus, tion ofobjectclass.WehaveomittedchanceIR/X-ray Figure 6apreliminarygraphofLversus,asfunc- in theHngalaxycategory. limits ofthegraph).Allnon-AGN“normal”galaxieshavebeengrouped sources intheB92catalog.WehaveincludedfiveQSO/BLLacobjects with theSeyfert1-1.5galaxies(theluminositiesofthreeQSOsexceed xFIR To explorethepossibilitythat star-forminggalaxiesor Nonetheless, thedomainsinFigure6ofvarious Fig. 6.—Lvs.Lp^for168securelyclassifiedextragalacticPSC/RASS x 8. SUMMARY 395 19 96ApJS. .106 . .341M 1 43-1 appears asthoughtheSeyfertcomponentincomposite examination oftheiremission-linespectrarevealsvery objects isunusuallyweakintheoptical.Becausecom- we findthatthestarburstcomponentincomposite X-ray luminositiescomparabletothoseofthecomposites, lines, andinsomecases,weak,broadHaemission(2500- spectra isnotunusuallystrongandthereforecapable starburst galaxies,andSeyfertsintheB92samplewith width measurementsforthecomposites,nearbyspiraland subtle Seyfertsignatures:[Om]linesbroaderthanallother of overpoweringanopticallytypicalAGN.Instead, it 3600 kms“FWHM).BasedonHa+[Nn]equivalent 5 x10ergss,aretypicalofSeyfertgalaxies.Careful burst, yettheirX-rayluminosities,whichrangeupto class ofX-ray-bright,opticallyinnocuousobjects,whichwe Antonucci, R.J.,&Miller,J.S.1985,ApJ,297,621 Allen, S.W.,etal.1992,MNRAS,259,67 spectra thataredominatedbythecharacteristicsofastar- have dubbed“starburst/Seyfertcomposite”galaxies. Allen, D.A.,Norris,R.P.,Meadows,V.S.,&Roche,P.F.1991,MNRAS, led ustotheprincipalresultofthiswork:discoverya Boiler, T.,Meurs,E.J.A.,Brinkmann, W.,Fink,H.,Zimmermann,U.,& variability (Boileretal.1994).Carefulspectroscopyhasalso touted tobethefirstHngalaxydemonstraterapidX-ray Boyle, B.J.,Griffiths, R.E.,Shanks,T.,Stewart,G.C, &Ceorgantopoulos, Boroson, T.A.,& Green, R.F.1992,ApJS,80,109 Bookbinder, J.,Cowie,L.L.,Krolik, J.H.,Ostriker,P.,&Rees,M.1980, Boiler, T.,Trümper,J.,Melendi,S., Fink,H.,Schaeidt,S.,Caulet,A.,& Boiler, T.,Fink,H.,&Schaeidt,S.1994, A&A,291,403 Boiler, T.1993,privatecommunication Barcons, X.,&Fabian,A.C.1990,MNRAS,243,366 Bergeron, J.,D’Odorico,S.,&Kunth,D.1987,A&A,180,1 Balzano, V.A.1983,ApJ,268,602 best candidateforanarrow-line(type2)quasar(Elizalde& I Zw1-typeobjectIRAS20181—2244,thoughttobethe Steiner 1994),andtheSeyfert1.8galaxyIRAS15564+6359, objects reportedpreviouslytopossesuniquequalities:the an illustration,wehaveusedourspectratoreclassifytwo spectroscopy isindispensabletoastudysuchasthisone.As in thissamplearebroademission-lineactivegalacticnuclei. further confirmation.Byfar,thedominantclassofobjects viously unrecognizedcontributionoftheXRB. galaxies representedintheB92catalogmakealarge,pre- Thus, thereremainsnoevidencethatthetypesofstarburst fication asanHngalaxyisquestionableandrequires either theiridentificationasanX-raysourceorclassi- galaxies 5-10timesmoreluminousthananystarbursts dim. Fiveobjectsinthepresentsamplemaybestarburst (and elsewhere:PaperI;Halpernetal.1995;Moran observed previouslyintheX-rayband,buteachcase spiral galaxiesandstarbursts(B92),wehaveshownhere sample containsanewclassofX-ray-luminousnormal first time.Ournewopticalspectraserveasarepresentative spectral atlasofIR-andX-ray-selectedgalaxies. involved carefulopticalspectroscopy,areviewoftheliter- RASS catalogareclassified,with105presentedhereforthe sample. 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