2 O 02MNRAS.331. .154R 2 12 1 resolution, andthereforesmallercontaminationfromanycircum- region (BLR)aredirectlyvisible,whileinSeyfert2(Sy2)galaxies Mon. Not.R.Astron.Soc.331,154-168(2002) European SouthernObservatory,Karl-Schwarzschild-Str.2,D-85748GarchingbeiMünchen,Germany [email protected] (MAP) infrared (NIR;e.g.Veilleux,Goodrich &Hill1997),wherein nuclear starformation,canbeachievedbyobservinginthenear- the torushavemostlybeencarriedoutatmillimetrewavelengths invariably alignedwiththeradiojets. images (e.g.Mulchaey,Wilson&Tsvetanov1996)almost Moran etal.2000),believedtobelightfromtheBLRreflectedinto line region(NLR)isvisible.Thesemodelsaresupportedbythe the torusobscuresnucleusandBLRonlynarrow- nucleus. InSeyfert1(Syl)galaxiesthenucleusandbroad-line Antonucci 1993),whereathickmoleculartorussurroundsthe Arguably themostimportantadvanceinrecentresearchofactive Accepted 2001November15.Received15;inoriginalformMay9 J. Reunanen,*K.KotilainenandM.A.Prieto Near-infrared spectroscopyofnearbySeyfertgalaxies-I.Firstresults only thetotalmolecularcontentinnucleus.Betterspatial our lineofsight,andcone-likestructuresinnarrow-band[Om] detection inmanySy2sofbroadlinespolarizedemission(e.g. galaxies hasbeenthedevelopmentofunifiedmodels(e.g. ^E-mail: [email protected](JR); [email protected] (JKK); addition tothemolecularHlines awealthofotheremissionand (e.g. Maiolinoetal.1997),andconsequentlytheygenerallygive 1 INTRODUCTION Tuorla Observatory,UniversityofTurku,Väisäläntie20,FIN-21500Piikkiö,Finland 2 Searches fortheobscuringmolecularmaterialassociatedwith © Royal Astronomical Society •Provided bytheNASA Astrophysics DataSystem be strongerthanBryorH1-0S(l),whileintheSeyfert1NGC1566and1.5 We presentnear-infrared1.5-2.5jammoderate-resolutionlong-slitspectraoftwoSeyfert1 to thecone.Coronallinesaredetectedintwogalaxies,NGC1386and3227. is detectedinthreegalaxies(NGC1386,1566and3227),ofwhichNGC1386optically NGC 3227Bryisthestrongestline.Broadoriginatingfrombroad-lineregion(BLR) the excitationmechanismsofinterstellargas.InallthreeSeyfert2galaxies,[Fen]isfoundto ABSTRACT Key words:galaxies:active-nucleiSeyfertinfrared:galaxies. exception tothisistheSeyfert2NGC1386,wheretwoextendedregionsaredetectedparallel with activegalacticnucleus(AGN)unifiedmodels.ThevaluesofnuclearAarehigherin galaxies exceptinNGC5128,thespatialfullwidthathalf-maximum(FWHM)sizeofH classified asSeyfert2.Inthesegalaxies[Fen]isnarrowandmaybeX-rayexcited.all galaxies (NGC1097and1566),threeSeyfert2s1386,49455128)one Seyfert 2sthaninIs,withthe1.5NGC3227lyingbetweenthem.The are usedtostudythespatialextentoflineemission,integratedmassesexcitedHand 1 -0S(l)nuclearcoreislargerperpendiculartotheconeorjetthanparallelit,inagreement 1.5 (NGC3227),bothparalleltoanionizationconeorjetandperpendicularit.Thespectra 2 Ho 2 2 _1 positioned bothperpendicularandparalleltotheionizationconeor both typeswithanionizationconeand/orjets.Theslitwas been carriedout(e.g.Storchi-Bergmannetal.1999;Winge from theemission-linestudyofall the14Seyfertsinoursample, molecular gasinthecentralregions. trace thespatialdistribution,dynamicsandexcitationofmolecular images areavailableforallthegalaxies.Thesedatausedto to thejetinorderprobedistributionofmolecularmaterial moderate-resolution spectroscopyofthefirstsixgalaxiesinour molecular emission. 2000), buteventhesestudieshaveonlyoneslitpositionangle(PA) Seyfert spirals. sample, basedontheabsorption lines andcomparisonwithnon- and studythestellarpopulations and star-forminghistoriesofthe and nebulargas,todeterminethemassofhot(T>1000K) and thusthegeometryoftorus.Additionally,broad-bandJHKs- sample ofnearby(5001.5 arcsec).OnlyrecentlyhavebetterresolutionNIRstudies studies havemostlybeenmadeatmoderatespatialresolution absorption linesareavailable.However,theNIRspectroscopic [Om] images,andthuscannotderivethegeometryof This paperisorganizedasfollows. InSection2theobservations, In forthcomingpublications,weshalldiscusstheimplications In thispaperwepresenttheresultsoflong-slit1.5-2.5pm © 2002RAS 2 O 02MNRAS.331. .154R -1 1 -1 1 Hq =75kmsMpcand0.5areassumed. region withnolineemission was subtractedtoremovethe region asdeeplypossible,allthespectraofagivengalaxywere redshift, scale,inclination,PAofthemajoraxis,morphology,AGN presented inKotilainenetal.(2000).Thepropertiesofthegalaxies, resolution R=980andslitwidth1.0arcsec(0.6forNGC respectively. Inthespectroscopicobservationsredgrismwith Foundation. which areoperatedbytheAssociation ofUniversitiesforResearchin For fewlines,especiallyfor[Cavm]inNGC1386,anoutlaying the effectiveaperturehasadiameterof1.4or1.1arcsec.Thefluxes The nucleuswastracedbyfittingalow-orderpolynomial,strip using eitherOHnightskylinesorXearclampcalibrationframes. from eachother.Theimageswerethenflat-fieldedusingdome PA oftheconeorjet.Theintegrationsweretakenintwopositions type, thePAsused,totalintegrationtimes,slitwidthandfull the usefulslitlength—2arcmin.Broad-bandJHKsimageswere METHODS OFANALYSIS 2 OBSERVATIONS,DATAREDUCTIONAND Astronomy, Inc.,undercooperativeagreement withtheNationalScience and widthsofthelinesdetectedinthisaperturearegivenTable2. extracted. Asaresultofthisandtheslitwidth(1.0or0.6arcsec), combined andthecentral1.5-arcsec(5pixel)spectrumwas were binnedtogether.However,thesizesgivenlaterfornuclear good signal-to-noise(S/N)ratio,andthereforetwoormorepixels averaged, irafwasusedforallstagesofthedatareduction. divided byanatmosphericstandardstar,fluxcalibratedand continuum andOHlinesfromthesky.Finally,imageswere was extracted,andthestripswereaveragedtoeraseresidual were removedmanually.Theimageswavelength-calibrated flats. Badpixelsweremaskedoutandanyremainingcosmicrays along theslitseparatedby—2arcminandpairsweresubtracted at halfmaximum(FWHM)seeingaregiveninTable1. also obtained,exceptforNGC1097,whichweusedtheimage during theobservationswere0.65,—1.0and1.35arcsec, 3.6-m ESONewTechnologyTelescope(NTT)usingthe1024X Six nearbyactivegalaxieswereobservedin1999Januarywiththe we presentourpreliminaryconclusions.Throughoutthispaper, Section 3thegalaxiesarediscussedindividually,andin4 data reductionandmethodsusedintheanalysisareoutlined.In sources arebasedonunbinneddata.Inordertoprobethenuclear scale 0.29arcsecpixel.Thebest,averageandworstseeing © 2002RAS,MNRAS 331,154-168 irafisdistributedbytheNational OpticalAstronomyObservatories, 1386) wereused.Thewavelengthrangecoveredis1.5-2.5gumand 1024 pixelSOFIcamera(Lidman,Cuby&Vanzi2000)anda The accuratedeterminationoffluxesandlinewidthsrequiresa The long-slitspectraweretakenparallelandperpendiculartothe NGC 5128 NGC 4945 NGC 3227 NGC 1566 NGC 1386 NGC 1097 Galaxy Table 1.Observationalpropertiesofthegalaxies. © Royal Astronomical Society •Provided bytheNASA Astrophysics DataSystem 0.00179 0.00194 0.00382 0.00483 0.00289 0.00425 -1 0 pc arcsec Scale i 74 94 56 82 19 19 78 74 46 65 56 28 141 158 PA MorphologyNucleus 43 25 30 30 SAB(s)a pec SAB(s)bc + SBcdsp SB(s)b SB0 E2 Syl.5 Sy2 Sy2 Syl Sy2 Syl 4 -185 4-3 We haveestimatedtheextinctionbycomparingobserved roughly bedividedintothreeclasses:coolorwarmmolecular been usedintheanalysis.Thesefeaturesarenotartificialor be usedtoestimatetheextinction.Ausefullinepairin pairs weregenerallydetected.OnlyinNGC4945theBr£andBrr/ may notbecorrectforthelineemission.However,nouseful th&H —KcolourofSOorEgalaxiesresemblesthespiral unobscured spiralgalaxies(H—K=0.22,Huntetal.1997),as integrated coloursfromthespectrawithofnormal, 2.1 Extinction underlying absorptionlines.Thequotederrorsinthefollowing Thermal excitation,eitherbyshocks (e.g.Hollenbach&McKee Hei) andveryhot,highlyionized matternearthecentreof mechanisms oftheinterstellarmatter.Sourceslineemissioncan The emission-lineratioscanbeusedtoprobetheexcitation 2.2 Hmoleculargas:excitationandmassestimate telluric, asthevelocityfieldderivedfromthemagreeswith NGC 1386,1566,3227and5128,asmarkedintherespective the sameD/2level.Thesefaintemissionlinesaredetectedin the centralregionandinlowestpanelofspatialprofile have assumedtheextinctionlawocÀ(Fandinietal.1984) lines and/orthecontaminationfromnearbyabsorptionlines.We The difficultyofdetectingotherHulinesarisesfromthehigh is similartothatderivedfromthecontinuumcoloursofspectra. lines arevisibleinafewregionsandtheextinctionbasedonthem extinction basedoncontinuumcoloursortheslopeofspectra galaxies (Fioc&Rocca-Volmerange1999).Wenotethatthe galaxies (coronallines).Themain mechanismsfortheHemission clouds (Hlines),warmionizedinterstellar gas(Hulines,[Fen], general rotationofthegalaxies. extended thanthemain1.64-jamline.Forthisreason,theyhavenot figures. However,thelinesaregenerallymuchbroaderandmore 2000; here0.37). with previousmeasurements(e.g.H—K=0.34,Kotilainenetal. with thepreviousderivations:e.g.inNGC4945Marconietal. figures. Ourextinctionmeasurementsareinfairlygoodagreement extinction thesegalaxiessuffer,theintrinsicweaknessofHit are thermal(collisional)heatingand UVpumping(fluorescence). and aforegrounddustscreen.TheextinctionisgiveninTable2for sections aregenerallydominatedbythecontinuumfitting,and (1996) derivedAy~1.1fromthecontinuumcoloursand> 1er except3stars)and[Fen] Figure 5.ThevelocityfieldofNGC1097inthemostimportantemission collisionally excited. fluorescent excitationcannotbe significant. Weconcludethatin otherwise stated. S(l) lineisnarrowerthan[Fen],withintrinsicFWHM270kms. Kotilainen etal.(2000).Thedistancesquotedarecorrectedfor (triangles). (Tvib <2400K)inthecentral1.4-arcsecaperture,indicatingthat starbursts (^300kms;e.g.Moorwood&Oliva1988).The1-0 (intrinsic FWHM400kms),althoughwiderthanintypical subtracting theunderlyingCOfeatures.The[Fen]lineisnarrow 1097 aregiveninTable3.Inthe nuclear 1.4-arcsecaperture,the 2 MR spectroscopyofnearbySeyferts-I159 The derivedparameters,including thedensityandmassof In theHband(Fig.3),[Fen]canonlybedetectedafter Position [”] 2 O 02MNRAS.331. .154R + 17-2 While Bryand[Fen]areonlymarginallyresolved,the1-0S(l) region (e.g.Malkan,Gorjian&Tam1998).NGC1386hasastar- parallel tothejets(40and50M)thanperpendicularthem nucleus ofNGC1386(Fig.6).Strongest ofthesecoronallinesis There isnoextendedemissionperpendicular tothecone. the south.Thenuclear1-0S(l)coreisnotresolvedparallelto north. Theslitwasalignedtoincludethisregion. Bergmann etal.(1996b)hasaseparateemissionregiontothe taken byWingeetal.(2000).The[Om]imageofStorchi- forming ringwithmajoraxisdiameter—1.3kpc(Weaver,Wilson Fornax clusterwithaSy2nucleusanddustlanesacrossthenuclear NGC 1386isanearby(distance=11.5Mpc)SB0galaxyinthe 3.2 NGC1386 kinematics ofH,Bryor[Fen], Ha velocityfield.Therearenosignificantdifferencesbetweenthe the jets.However,furtherawayingalaxyHemissionwasnot integrated massofexcitedHinsidethestarburstringislarger cone, whileintheperpendiculardirection itismarginallyresolved. galaxy) towardsthenorthand—3.5arcsec(340pc) emission canbetraced—4.5arcsec(440pcintheplaneof detected separateregionsarediscussedindetailbelow.TheH emission isextendedparalleltothecone,wheretwoclearly extended atPA—170°,whichisdifferentfromtheopticalmajor emission linesinthejets(Wehrleetal.1997). discrepancy isinagreementwiththenon-detectionofoptical detected, whiletheopticaljetscontinuemuchfurther.This column densityofexcitedmolecularhydrogenis1.5X10cm along themajoraxis.Low-resolution(R=250)///AT-spectrawere axis PA(—25°).Weaveretal.(1991)detectedanoutflowdirected & Baldwin1991).Thenuclearradiocore(Nagaretal.1999)is Our NIRvelocityfields(Fig.5)areingoodagreementwiththeir Storchi-Bergmann, Wilson&Baldwin(1996a),whofoundthe shown inFig.6,whiletheextentoflinesisdisplayed7. starburst ringtobelocatedbetweentheinnerLindbladresonances. (—30 Mq).ThissuggeststhatHemissionisproducedbyshocksin (corresponding toMh=25Mq),assumingT2000K.The [Sivu] anditisalsooverallthe strongestobservedlineinthe [Caviii] 2.3213pmand[Sivu] 2.4833 pm)aredetectedinthe 160 J.Reunanenetal. 0 2 2 2 2 2 2 Three spatiallyunresolvedcoronal lines([Sivi]1.9635p-m, The H-andAT-bandspectraofNGC1386alongtheconeare The kinematicsofNGC1097hasbeendiscussedindetailby © Royal Astronomical Society •Provided bytheNASA Astrophysics DataSystem Figure 6.The1.5-2.5|xmspectraofNGC1386paralleltothecone. 17-2 been detectedintheSy2sCircinus(Olivaetal.1994)andNGC to Mh—20Mq)withinthenuclear 1.1-arcsecaperture.The1-0 nucleus. Theupperlimitto2-1 S(l)/l-0 S(l)ratio,^0.12,is nucleus is0.48,compatibleeitherwithshocksrelativelylittle have beensubtracted(Fig.6).Thereisaredwinginboth[Sivu] nuclear spectrum.Previously,the[Caviii]coronallinehasonly ionization cone(opensymbols)andparalleltoit(filledsymbols).ThePSF Figure 7.TheobservedlineemissioninNGC1386perpendiculartothe compatible withthermalexcitation withTAb^2310K.Assuming excitation (Contini&Viegas2001). contribution fromUYexcitation,orwithstrongUVcontinuum features havebeensubtracted.The[Sivi]/[Sivu]ratiointhe r =2000K,wederiveY 3.9 X10cm(corresponding and [Sivi],possiblyin[Caviii],aftertheCOabsorption (short-dashed line)andperpendiculartoit(long-dashedline). shown. Inthelowestpanelextinctionisshownparalleltocone (dotted line)andthe2.09-pmcontinuumemissionmultipliedby10arealso 1386 isalreadyclearlyvisiblebeforetheunderlyingCOfeatures 1068 (Marconietal.1996),andunlikeinthem,[Caviii]NGC 2 vibH2 We didnotdetect2-1S(l)nor 1-0S(0)emissioninthe Position ["] © 2002RAS,MNRAS 331,154-168 2 O 02MNRAS.331. .154R -152 respectively, ina1.4-arcsec(1.1arcsecforNGC1386)apertureunitsof Figure 9.The1-0S(l)(crosseswitherror bars),[Fen](triangles)andBry narrow 1-0S(l)forNGC1386,1566and3227fromtoptobottom, Figure 8.Enlargedspectralareaaround2.15jamshowingbroadBryand hand, the[Feii]/Bryratiois7.1,suggestingasignificant is insignificant,asthenBryshouldbemuchstronger.Ontheother cone (C)andperpendiculartoit(P). (stars) velocitycurvesforNGC1386, 1566, 3227and5128paralleltothe contribution fromX-raystotheionization.AsBryisbroad, S(l)/Bry ratiois1.14,stronglysuggestingthatthermalUVheating © 2002RAS,MNRAS 331,154-168 10 ergscmÂ. © Royal Astronomical Society •Provided bytheNASA Astrophysics DataSystem Wavelength[/¿m] Position ["] 2 -1_ 1 172 rotation curveisrelativelyorderedparalleltothecone,suggesting ring isvisibleintheKsband(Fig.1). regions AandB,respectively.Thesemassesarecomparableto regions thaninthenucleus,whilelinefluxesarecomparableto band images.ExtinctionderivedfromcontinuumcoloursisA= The mostinterestingfeaturesinFig.7arethetwoextendedH 3.2.1 Twoextendedregionsparalleltothecone that circularmotionsdominatethekinematics. the nucleusinHa;Storchi-Bergmannetal.1996b).However, the reducedeffectofextinctioninNIR.Thereisnodetectable the ratiosderivedaboveareinfactlowerlimits.Thelikely nucleus inthehigh-resolution[Om] mapofSchmitt&Kinney Mulchaey, Regan,&Kundu1997), ringed(diameter1.7kpc) NGC 1566isanearby(distance=19Mpc)barred(PA—0°; 3.3 NGC1566 the masswithin1.1-arcsecnuclearaperture,—20Mq. two regionsof2.3X0.6arcsec(—4350pc)areais—1OM thermal excitation.ForregionB,thetwoderivedtemperatures the 2-1S(l)/l-0S(l)upperlimit(rb<2100K)assuming the instrumentalresolution(—22A).The2-1S(l)linewasnot those inthenucleus.Thelinewidthsareonlyslightlylargerthan visible inthetworegionsowingtomuchfaintercontinuumthese 4945 (Section3.5). than inthenucleus(Table4),contrasttosituationNGC 4.4-2.3 arcsectothenorthandregionB1.1-3.2 emission regionsparalleltothecone.RegionAcoversarea considering itsfaintness(onlyafewpercentofthebrightness emission fromthestarburstring,whichisnotsurprising component tothe[Fen]line,soobservedemission originate fromtheBLR.Thereisnocorrespondingbroad optical lines(e.g.Rossa,Dietrich&Wagner2000),andislikelyto excitation mechanismfornebulargasisthereforeX-rays,further clouds. The1-0S(0)/1-0S(2)ratiois0.60and0.46forregionsA detection ofBrysuggeststhermalexcitationinshock-heated 2100K forregionsAandB,respectively.Furthermore,thenon- detected ineitherregion,settingupperlimitsofras2600Kand 0.03 andA=0.09mag,whilethatderivedfromthe1-0 arises outsidetheBLR.Bryisconcentratedinnucleus,and S(l) and[Fen]emissionaresymmetric.Bryisbroaderthanthe SAB(s)bc galaxyintheDorado group withaSylnucleus.The agree withinerrors. 3200 K.ForregionA,thistemperatureisingoodagreementwith and B,respectively,iscompatiblewithT—1800Kor and B,respectively.TheHlinesinthesetworegionsarenarrower Q(3)/l-0 S(l)ratioisA=0.04and0.20forregions strong Hapeak(Rossaetal.)isnotdetectedinBry,demonstrating (—800km s)comparedwith1-0S(l)(190km. supported bythemuchlargerwidthof[Fen](560kms~)andBry south-east. Toourknowledge,noNIR spectroscopyhaspreviously (59pc). The[Om]mapalsoshows conicalextendedemissionin (1996) isalmostpoint-like,with maximumextentof0.7arcsec (Ah =L9xl0cm-)and-30M(3.8X10cm“,for south ofthenucleus.Neitherregionsisvisibleinbroad- 2 2 0 vi vib 2 mi 2 2 2o MR spectroscopyofnearbySeyferts-I161 The velocityfieldofNGC1386isdisplayedinFig.9.H The Brylineisbroadandasymmetric(Fig.8),whileboth1-0 The massoftheexcitedmolecularhydrogenassociatedwith Many oftheweakerHlinesnotdetectedinnucleusare 2 2 2 O 02MNRAS.331. .154R -1 -1 _1 _1 plane ofthegalaxy)fromnucleusparalleltoconeand parallel totheconethanperpendicularit(Fig.11).Oflines been obtainedforNGC1566.The1.5-2.5|jimspectrumis heating withinthetorusonscales ofafewpc. X-ray heatingmodelsbyKrolik &Lepp(1989),whichpredict The [Fen]lineisnotspatiallyresolved, inagreementwiththe mechanism foriron,possiblyX-rayexcitationoutsidetheBLR. lack ofthenarrowBrycomponentindicatesadifferentexcitation Bry. Similarly,thereisnobroadcomponenttothe[Fen]line, however, onlywithinthecentral1arcsec,withnoextended nuclear 1-0S(l)emissionis—1.3arcsecperpendiculartothecone The 1-0S(l)emissionisdetectedupto~2arcsec(—200pcinthe which canbeexplainedifextinction emission. Thenuclear[Fen]lineisnarrow(FWHM= 2100 kmsinthecombinednuclear1.4-arcsecapertureafter difference betweenthetwoPAs. detected inNGC1566neither[Fen]norBryisspatiallyresolved. displayed inFig.10. Tib^ 2700K),significantlyless thanpredictedforUV 600 kms),whilethereappearstobenonarrowcomponent 600kms inthenuclear1.4-arcsecaperture.Thewidthof are rathernarrow,withintrinsicFWHMs430kmsand and —1.2arcsecparalleltothecone.The1-0S(l)[Feit]lines subtracting theneighbouringabsorptionlines.Itisdetected, —280 pcperpendiculartoit.TheintrinsicspatialFWHMofthe 1566, with2-1S(l)/l-0S(l) ^0.17(correspondingto 1-0 S(l)lineisroughlyconstantalongtheslit,withnodetectable 162 v The H2-lS(l)linewasnotdetected inthenucleusofNGC The Bryemissionlineisbroad(Fig.8),withFWHM= Both thelineandcontinuumemissionappearmuchweaker 2 J. Reunanenetal. © Royal Astronomical Society •Provided bytheNASA Astrophysics DataSystem Line observedcorrectedFWHMEW lines inthetwoextendedregionsNGC1386. 2- 1S(l) Table 4.Observedfluxes,reddening-correctedGaussianFWHMsandequivalentwidthsforthevariousHemission 1-0 Q(3) 1-0 S(2) 1-0 Q(l) 1- 0S(0) 1-0 S(l) 2 19.5 ±0.8 134 ±2 4.2 ±0.7 7.0 ±01.0 -162 17 ±2 10 ergscmÁ <2.3 Figure 10.The1.5-2.5-jxmspectraofNGC1566perpendiculartotheionizationcone. A2.2 3mag.However,the <2.4 20.1 14 18 4.3 7.3 Region A 22.8 : 22.7 : 20.4 ±3.9 24.6 ±1.0 25.6 ±3.2 1.5 1.6 Wavelength [¿¿m] 2.2 ±0.4 3.0 ±0.5 8.8 ±0.4 12 ±2 15 ±2 <1.2 -1 1 R =700-1000).InournewspectratheEWof[Fe11]and1-0S(l) lines, [Sivi]and[Alix]2.043pan. Aftersubtractingtheoff-nuclear FWHM =650kms). Larkin (2000;R=550)andSchinnerer,Eckart&Tacconi(2001; NIR spectroscopyofNGC3227hasbeenobtainedbyRhee& imaged withHSTinthe1-0S(l)andS(3)linesbyQuillen NGC 3227isanearby(distance=15Mpc)barred(Mulchaeyetal. 3.4 NGC3227 kinematics. molecular hydrogenalongthedirectionofionizationconeis that thedominantmechanismforexcitationofHgasis UY heating.The[Fen]/Bryratiois0.50,butsinceBrydoesnot derived bySchinnereretal.On theotherhand,Bryismuch complicates subtractingthecontinuumincentre.Recently, et al.(1999),althoughtheverystrongnuclearemission with radius,thussuggestingthatcircularmotionsdominatethe field (Fig.9)appearsrelativelyordered,withincreasingvelocities collisional viashocks.Theintegratedmasstheofexcited excitation cannotbelargerthan—10percent.Therefore,itseems display anarrowcomponent,starburstcontributiontotheUV fluorescence. The1-0S(l)/Bryratiois0.27,suggestingthermal spectra thaninthosebySchinnerer etal.(EW=3.7A; stronger andbroader(EW=8.3Á; FWHM=1800kms)inour and theintegratedcoloursareingoodagreementwiththose sided conetothenorth(Schmitt&Kinney1996).Ithasbeen —90 M©andperpendiculartoit—110M©.The1-0S(l)velocity 1997; PA—150°)SABgalaxyhostingaSyl.5nucleuswithone- 2 Schinnerer etal.(2001)reported the detectionoftwocoronal 35.7 ±0.8 14.6 ±1.0 observed correctedFWHMEW -162 6.8 ±0.7 26 ±2 29 ±2 10 ergscmÁ <2.4 <2.7 28 31 39.0 16.1 7.4 Region B 22.7 : 21.9 : 21.3 ±2.3 26.7 ±0.6 23.8 ±1.2 © 2002RAS,MNRAS 331,154-168 1.3 1.4 10.1 ±0.5 10.8 ±0.6 7.3 ±0.2 2.8 ±0.2 1.5 ±0.2 <0.6 2 O 02MNRAS.331. .154R _1 _1 presence ofneighbouringabsorptionlines(e.g.2.1770p,mand by Rhee&Larkin(2000).Unfortunately,outsidethenucleus factor of5. Figure 11.TheobservedlineemissioninNGC1566.panelsand no evidenceforextendedemission.Therefore,recentstar that derivedbyRhee&Larkin(2000). the S/Nratioinourspectraisnotsufficientlyhightosubtract this resultishardlyconclusivebecauseoftheatmospheric for thepresenceof[Alix](Fig.12).The[Sivi]lineispresent,but symbols areasinFig.7,exceptthecontinuumemissionismultipliedbya of thebroadcomponentis2500-3000kms(Fig.14),similarto 650kms, asderivedbySchinnereretal.(2001),theFWHM 2.1460 p.m).FixingthenarrowcomponentatFWHM= continuum anddeterminethelineprofileaccurately,in component FWHM—1800kms',inagreementwiththeresults at amuchweakerlevelthanreportedbySchinnereretal.However, signatures. spectra toreducetheresidualtelluriclines,wefoundnoevidence © 2002RAS,MNRAS 331,154-168 The nuclearBryemissionisspatiallyunresolved(Fig.13),with The BrylineisbroadinNGC3227(Fig.8),withsingle © Royal Astronomical Society •Provided bytheNASA Astrophysics DataSystem Figure 12.The1.5-2.5jjumspectraof NGC3227paralleltothecone. Wavelength [/¿m] 17-2 brightness. responsible fortheexcitationofH.Innuclear1.4-arcsec be duetolinesplitting,whichisnotdirectlydetectablewithour nuclear extentinthedirectionsparallelandperpendicularto to gasmassof280M,inagreementwiththe380 the nucleus,1-0S(l)/Bryratio>1,suggestingshockstobe UV fluorescenceasthedominantexcitationmechanism.Outside these galaxies,however,[Fen]isspatiallyresolvedinNGC3227. to it,andextendspredominantlytowardsthenorth.Thiseffectmay Bry originatesmuchclosertothecentralenginethan[Fen].The nent. Neither1-0S(l)nor[Fen]havebroadprofiles,indicatingthat formation hasbeenoccurringinthediscofNGC3227.However, NGC 4945isanearbySB(s)cdgalaxyintheCentaurusgroupof 3.5 NGC4945 is noisierandflat. the surfaceofhollowionizationcone.InSchinnereretal. This suggeststhatboththeexcitedHand[Fen]areemittedfrom to theionizationconethanperpendicularit,similarly[Fen]. emission arespatiallyresolved,withnocleardifferenceinthe derived byFernandezetal.(1999)fromthepeakHsurface which suggeststhatthenarrownebularlinesareexcitedbyX-rays, close tothenucleus,whichmayalreadyhavepassedionizing galaxies, withadustlanesouth-eastofthenucleus.NGC4945has dynamics asthatof1-0S(l).Perpendiculartotheconecurve especially paralleltothecone,and[Fen]appearshavesame due totheirpoorerspatialresolution(—1.6arcsec). elongated alongPA—100°.The1-0S(l)lineisbroaderparallel cone. Inthe1-0S(l)imagebyQuillenetal.(1999)emissionis aperture, thegasdensityNu=23AX10cm,corresponding as inthecaseofNGC1386or1566(seeabove).Unlike Schinnerer etal.(2001)detectedayoung(25-50Myr)starcluster spectral resolution.Thenarrow[Fen]/narrowBryratiois—7.8, stage. Alternatively,itmaybetheoriginofnarrowBrycompo- (Marconi etal.2000)withaprojectedmajoraxisdiameter strong starburstactivity,concentratedinacircumnuclearring (2001), the[Fen]linewasnotspatiallyresolved,butthismaybe [Fe ii]lineisbroaderinthedirectionofconethanperpendicular 2 0 2 2 2 MR spectroscopyofnearbySeyferts-I163 Both the1-0S(l)emissionand,moremarginally,[Fen] The nuclear2-1S(l)/l-0S(l)ratiois0.08,clearlyrulingout The velocityfieldiswell-orderedandresemblessolidrotation, 2 O 02MNRAS.331. .154R _1-52 _21 _1-5 powerful starburstandnotrepresentanoutflowfromthenucleus,is Harris 1998).Thehollowcone,whichmaybeproducedbya X-ray sourceabovelOkeY(Iwasawaetal.1993),whichis narrow component(FWHM=650km s,flux4.2X10ergcm) Figure 14.TheBrylineprofileofNGC 3227.Thefitisobtainedwitha For panelsandsymbols,seeFig.7. Figure 13.ThespatialextentofthethreemainemissionlinesinNGC3227. north-west ofthenucleus(Moorwoodetal.1996). completely obscuredbelowlOkeV.Inthefollowingwehave on thedetectionofaheavilyobscured,rapidlyvariable,stronghard ergcms). and abroadcomponent(FWHM =2700kms,flux23X10 clearly visibleatshorterwavelengths(À<2pm),especially adopted adistanceof3.9MpcforNGC4945(Harris,Poole& superwind (e.g.Heckman,Armus&Miley1990)fromthe — Ilarcsec(210pc).NGC4945alsoharboursaSy2nucleus,based 164 J.Reunanenetal. © Royal Astronomical Society •Provided bytheNASA Astrophysics DataSystem Wavelength [angstroms] Position ["] 1 7 17-2 _1 _1 between BryandHeI,whilethebehaviourof[Fen]emissionis peaks at4arcsec(130pc)and7(230distance,while perpendicular and—3arcsec(260pc)paralleltothesuperwind. peak butisdominatedbyastar-formingring.Inthesuperwind broader inthedirectionofsuperwind(upto550kms result ofadecayingstarburstortruncatedinitialmassfunction rotational temperatureT—2000K.Adopting=K,the forming regionsouth-westofthenucleusperpendicularto toward thenorth-eastdeclineisslower. Toward thesouth-west,emissionrapidlydecreaseswithlocal The 1-0S(l)mapinMarconietal.showsanelongated He icanbetraced—6-8arcsec(—230pc)fromthenucleus the north-westthansouth-east.Anothertracerofyoungstars, their image.The[Fen]emissioncanbetracedfurtherouttoward the planeofgalaxy)correspondtosouth-eastandnorth- furthest fromus. the nucleusunlikeHa,probably becauseoflowerextinction, This isinagreementwiththatobservedHa(Heckmanetal. nucleus. toward thenorth-eastthansouth-west.However,—1-3arcsec He i/Bryratioisroughlyconstant,withslightlylargerratios(—0.4) than expectedforX-rayexcitationandcanbebetterexplainedby mass ofwarm(T=160K)H(2.4X10M©;Spoonetal.2000). important. nucleus. Theseratiosindicate,togetherwiththeenhancedHeiand the south-westitis—1.4at5arcsec(160pc)distancefrom is —1.0at2arcsec(180pc)distancefromthenucleusandtoward heating isnotimportant.However,towardthesouth-eastthisratio north-east andnorth-westofthenucleus,suggestingthatUV emission linesrelativeto1-0S(l)(Fig.17).Notably,thestar- west andnorth-westofthenucleus,inagreementwithourspectra. good agreementwiththatinMarconietal.Thenorth-westpeakat west partsofthering.The[Fen]emissioninourspectraisalso direction, thetwoBrymaximaseparatedby~2arcsec(180pcin with theirresults.ThePacrimageofMarconietal.showsnocentral of NGC4945.Ournewdata(Figs15,16)areingoodagreement west ofthenucleus,redwing inbothBryand[Fen]ismuch which intheNIRmakesitpossible toobservetheconesurface 0.2). Thismaybeduetoalowernumberofhigh-massstarsas density ofexcitedHinthenucleus—100Xl0cm different fromthem.TheBry/1-0S(l)ratiois0.1-0.5towardthe superwind isclearlyvisible.Thereareasonablecorrelation (PA —33°)nuclearemissionandextendedtothesouth- arcsec, butitissymmetricfurther out.Ontheotherhand,south- (—400kms) at—5arcsec(440pc)distancefromthenucleus. and 700-800kms,respectively)thanperpendiculartoit (IMF) inthisregion.Paralleltothesuperwind,ratioishigher, south-west thereisaregionwithsignificantlylowerratios(—0.1- shocks andstarformation.Perpendiculartothesuperwind, (corresponding tom^70M©),muchlowerthantheavailable agreement withcollisionalexcitationat=2000-2500K.The ~ 5arcsec(440pc)fromthenucleusappearsasanelongationin —0.8, both1arcsecnorth-westand0.5south-eastofthe [Fen] emission,thatUVemissionfromyoung,hotstarsis 1990). However,[Fen]and1-0S(l)arealsobroadersouth-eastof l-0Q(l)/l-0 Q(3)ratiointhenucleusis—1,andassociated mt 2 2 There arequitelargeradialchangesinthelineratiosofmain Marconi etal.(2000)presentedPacr,1-0S(l)and[Feit]images The 1-0S(l)emissionhasared wingwithinafewcentral Both the1-0S(l)andespecially[Fen]aresignificantly The [Feiij/Bryratioof—4.5atthenucleus(Fig.17)islower The 2-1S(l)/l-0S(l)ratioof—0.1-0.2(Fig.17)isingood © 2002RAS,MNRAS 331,154-168 2 O 02MNRAS.331. .154R 8 position angleforthelineofnodes PA=43°±1°(Abiesetal. rotation curveinthedirectionof the superwind.Itismostclearly better thestellarrotationasderivedfromabsorptionlinesthanthat blue wingisstronger.Alikelyexplanationforthisbehaviourthat Based onthevelocityfieldof[Fen] andassumingi=78°±2° most intriguingfeatureistheroughly sinusoidalformofthe mechanism. ThekinematicsofBryand[Fen]arebettercorrelated, the ringinclinationwithrespecttogalaxy. than intheunderlyinggalaxy,eitherintrinsicallyorasaresultof the line-of-sightrotationalvelocityinnuclearringishigher Figure 16.TheobservedlineemissioninNGC4945.panelsand derived fromeitherBryor[Fen],butcorrelationisnotperfect.The except towardthenorth-eastofnucleus.1-0S(l)follows and Bry,suggestingdifferencesinthedynamicsand/orexcitation field (Fig.18)of1-0S(l)isclearlydifferentfromthat[Fen] symbols areasinFig.7. seen inthevariousHlines,but is alsopresentinBryandHei. stronger thanthebluewing,whilenorth-eastofnucleus © 2002RAS,MNRAS 331,154-168 1987), wederiveadynamicalmass M=3.2X10q.This 2 dyn Both perpendicularandparalleltothesuperwind,velocity © Royal Astronomical Society •Provided bytheNASA Astrophysics DataSystem Figure 15.The1.5-2.5jjumspectraofNGC4945perpendiculartothesuperwind. 8 ranging from2.1to8.5Mpc;inthefollowing,wehaveadopted prominent radiojetswhichafter5kpcexpandintoplumes.The imaging. Foracomprehensivereview ofNGC5128,seeIsrael NIR Paa(Schreieretal.1998)and [Fen](Marconietal.2001) Bryant &Hunstead(1999).Inaddition, ithasbeenthetargetof NGC 5128(CentaurusA)isawell-studiedgalaxywithprominent 3.6 NGC5128 millimetre COobservations(Mdy~8X10Mq;Mauersberger value isslightlylessthanthatderivedintheinnerR^100pcfrom Figure 17.Thelineratiosofthemainemissionlineswithrespectto1-0 distance of3.9Mpc(Harrisetal.1998).PreviousNIRspectro- distance ofNGC5128hasbeencontroversial,withestimates dust lanes(e.g.Schreieretal.1996)andSy2nucleus.Ithasvery et al.1996). S(l) inNGC4945. (1998). scopic studiesofNGC5128include e.g.Marconietal.(2001)and n MR spectroscopyofnearbySeyferts-I165 The spectraofNGC5128atdifferent distancesfromthenucleus Position ["] 2 O 02MNRAS.331. .154R -1 2 perpendicular toit(26°)intheunitsofkms. perpendicular tothejetaredisplayedinFig.19.Thesubtracted largest ratioseverfound. to be5.1,andaftercorrectionforextinctioneven—15,oneofthe Especially, whilethenuclear1.4Xl.barcsec[Fen]/Bryratio nuclear spectrumisalmostfeatureless.Therearesomenotable Figure 18.Thevelocityfieldofthemainemissionlinesand/f-bandCO nuclear region.However,theonlyemissionlinethatcanbetraced observed bySimpson&Meadows(1998)=1.47,wefindthisratio differences betweenourspectraandthosefromtheliterature. absorption linesinNGC4945paralleltothesuperwind(-64°)and out intothegalaxyis1-0S(l)(Fig.20),whichextendsparallelto featureless nuclearcontinuum.[Fen]isthestrongestlinein weakness ofthelineemissioncomparedwiththatinNGC4945at similar distance.Thisispartlyduetodilutionbythebright,red, 166 J.Reunanenetal. -200 -100 -100 200 100 100 The moststrikingfeatureinthespectraofNGC5128is 0 o x r 1-0S(l) D Absorption < Bry ^ [Fell] NEl NW II^ © Royal Astronomical Society •Provided bytheNASA Astrophysics DataSystem ! □ D a X a a D □J s D Position ["] H- H- % 4i I Figure 19.The1.5-2.5pmspectraof NGC5128perpendiculartothejet. ** A* [q L 26° 26° -64° -64° J sw r SE II H 0 200 0 200 -loo -200 100 Wavelength [/xm] -200 17-2 respectively, whichdisplaytwoextendedregionsstraddlingthe perpendicular tothejetup16arcsec(690pc)north-west We havepresentedNIR1.5-2.5jamlong-slitspectraofsixSeyfert the necessaryresolutionordepthtosupplementtheirresults. Assuming rib=2000K,thedensityofHis45.6X10cm, limit of2-1S(1)/1-0S(1)^0.08(T<1900K).Sincethe1-0 nucleus. mostly unresolvedwithfaintextendedemissionnorth-westofthe nucleus atPA—33°.The[Fen]emissionofMarconietal.is images ofSchreieretal(1998)andMarconial.(2001), visible inourspectra,e.g.at—17arcsec(400pc)withdetectedBry from thenucleus.Marconietal.interpretedthisasaninclined, is notspatiallyresolved.Inthedeeper^-bandspectraofMarconi north-east and7.4arcsec(180pc)tothesouth-west, the jetupto13.4arcsec(320pcinplaneofgalaxy) line isevenstrongerthan[Fen],[Sivi]comparabletoo]and nucleus ofNGC1097.Notably,in1386thecoronal[Sivu] NGC 10971-0S(l),andintheSyl1566.5 4 CONCLUSIONS corresponding toagasmassof33.8M. component, thereareafewstar-formingregionsparalleltothejet et al.(2001)thenucleusisresolvedanddetectedupto1arcsec will bepresentedinforthcomingpapersusingthefullsampleof14 galaxies withanionizationconeorjets.Whilestatisticalanalysis agreement withMarconietal.(2001),butunfortunatelywelack S(l)/Bry ratiois2.04,theHgasprobablyexcitedbyshocks. and [Fen]emission.ThisisinagreementwiththePaa and 22arcsec(950pc)tothesouth-east.ThenuclearBryemission 3227 Bryisthestrongestemissionline.wasnotdetectedin strongest andBrytheweakestmainemissionlineinSy2sNGC Seyferts, somegeneraltrendscanalreadybenoted.[Fen]isthe —40 pcdiameter,thindiscofionizedgas.Inadditiontothecentral 1386, NGC4945and5128.Ontheotherhand,inSyl v2 v[h 0 2 No2-lS(l) emissionwasdetectedinthenucleus,withanupper Our velocityfieldforNGC5128isdisplayedinFig.9.It © 2002RAS,MNRAS 331,154-168 2 O 02MNRAS.331. .154R regions. be connectedwithanuclearoutflow.Astheextendedemission parallel totheconeinNGC1386.Theextended1-0S(l)emission to it. models andtheexistenceofamolecular torus.InNGC5128,onthe to theionizationcone/jetthanparallel toitinNGC1097,1386, The extentofthenuclearcoreHemissionislargerperpendicular further supportedby1-0S(l)velocitycurves,whicharegenerally the moleculargasformsadiscsurroundingnucleus.Thisis these regionsareassociatedwiththestarburstrings,whileinNGC NGC 1097,1386and4945separateoff-nuclear1-0 the planeofgalaxyinNGC1097to~1.4kpc4945.In the [Fen]emission(e.g.Mouri,Kawara&Taniguchi2000). NGC 1566and3227,inwhichthenarrowBrycomponentis Fig. 7. Figure 20.TheobservedlineemissioninNGC5128.Symbolsareas other hand,theextentislargerparallel tothejetthanperpendicular extent oftheemissiondoesnotdependontypenucleus. while theoppositeistrueinNGC3227,1566and5128,sototal cone/jet thanperpendiculartoitinNGC1097,1386and4945, extended emissionisassociatedwithoff-nuclearstar-forming detected inNGC1097and4945.Inthesegalaxies,the well-ordered exceptparalleltothesuperwindinNGC4945.A declines smoothlywithincreasingradius,itseemsprobablethat S(l) emissionregionsaredetected.InNGC1097and4945 can bedetecteduptoarangeofphysicalscales,from—200pcin agrees withthetheoryofX-rayexcitationinNLRasoriginfor only visibleinNGC3227.Basedonthehigh[Fen]/Bryratiosit also detectedinNGC3227. starburst originseemsexcludedasextendedBryor[Fen]isonly spatially resolvedonlyinNGC3227and4945,whichalso seems probablethat[Fen]isX-rayexcited.Theemission © 2002RAS,MNRAS 331,154-168 [Ca Yin]isstrongerthanBry.Inaddition,[SiVi]andvu]were 1566, 3227and4945,ingoodagreement withthecurrentunified 1386 theoriginoftheseregionsremainsunknown,butarelikelyto 2 There doesnotappeartobeaclear differencebetweenthegas The overall1-0S(l)emissionismoreextendedparalleltothe The 1-0S(l)emissionisextendedinallgalaxies,except Broad nuclearBrylineemissionwasdetectedinNGC1386, © Royal Astronomical Society •Provided bytheNASA Astrophysics DataSystem Position ["] paper wasbasedonobservationscollectedattheEuropean parallel tothecone/jetislargerthanperpendicularit.The Laboratory, CaliforniaInstituteofTechnology,undercontract Database (NED)whichisoperatedbytheJetPropulsion This researchhasmadeuseoftheNASA/IPACExtragalactic ACKNOWLEDGMENTS thermal excitation. for significantUYfluorescencewasfound.TheextendedH nuclear Hemissionappearstobetheresultofshocks.Noevidence highest nucleargasdensitiesA,arefoundintheSy2sNGC4945 the twomassesaresimilar,whileinNGC1097and1386 NGC 1566,3227,andespecially4945,paralleltotheconeis mass parallelandperpendiculartotheionizationcone.In Mouri H.,KawaraK.,TaniguchiY,2000, ApJ,528,186 Moran E.C.,BarthA.J.,KayL.E.,Filippenko A.Y.,2000,ApJ,540,L73 Moorwood A.F.M.,vanderWerfRR, KotilainenJ.K.,MarconiA.,Oliva Moorwood A.F.M.,OlivaE.,1988,A&A, 103,278 Mauersberger R.,HenkelC.,WhiteoakJ.B.,ChinY.-N.,TieftrunkA. 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