Astronomy&Astrophysicsmanuscriptno.aa˙paper (cid:13)c ESO2012 May15,2012 The Activity of the Neighbours of Seyfert Galaxies. E.Koulouridis1,M.Plionis1,2,V.Chavushyan2,D.Dultzin3,Y.Krongold3,I.Georgantopoulos1,J.Leoń-Tavares4 1 InstituteofAstronomy&Astrophysics,NationalObservatoryofAthens,PalaiaPenteli15236,Athens,Greece. 2 InstitutoNacionaldeAstrof´ısicaOpticayElectrońica,AP51y216,72000,Puebla,Me´xico. 3 InstitutodeAstronom´ıa,UnivesidadNacionalAutońomadeMe´xico,ApartadoPostal70-264,Me´xico,D.F.04510,Me´xico 4 AaltoUniversityMetsa¨hoviRadioObservatory,Metsa¨hovintie114,FIN-02540Kylma¨la¨,Finland May15,2012 2 1 ABSTRACT 0 2 Wepresentafollow-upstudyonaseriesofpapersconcerningtheroleofcloseinteractionsasapossibletriggeringmechanismof y AGNactivity.Wehavealreadystudiedtheclose(≤ 100 h−1kpc)andthelargescale(≤1h−1 Mpc)environment ofalocalsample a ofSy1,Sy2andBrightIRASgalaxies(BIRG)andtheirrespectivecontrolsamples.Theresultsledustotheconclusionthataclose M encounter appearscapableof activatingasequence whereanormal galaxybecomesfirstastarburst,thenaSy2andfinallyaSy1. However,sincebothgalaxiesofaninteractingpairshouldbeaffected,wepresent hereopticalspectroscopy andX-rayimagingof 4 15and16neighbouringgalaxiesaroundtwosamplesof10Sy1and14Sy2galaxiesrespectively.Basedonopticalspectroscopy,we 1 findthatmorethan70%ofallneighbouring galaxiesexhibitstarformingand/or nuclear activity(namelyenhanced starformation, starburstingand/orAGN),whileanadditionalX-rayanalysisshowedthatthispercentagemightbesignificantlyhigher.Furthermore, ] wediscoveredastatisticallyimportanttrend,ata99.9%level,regardingthetypeandstrengthoftheneighbour’sactivitywithrespect O to the activity of the central galaxy, i.e. that the neighbours of Sy2 galaxies are systematically more ionized than the neighbours ofSy1s,afactthatindicatesdifferencesinmetallicity,stellarmassandstar-formationhistorybetweenthesamples.Ourresultsare C consistentwiththelinkbetweenclosegalaxyinteractionsandactivityandalsoprovidemorecluesregardingthepossibleevolutionary . h sequenceinferredbyourpreviousstudies. p Keywords.Galaxies:Active,Galaxies:Seyfert,Galaxies:Starburst,X-ray:Galaxies,Cosmology:Large-ScaleStructureofUniverse - o r t s 1. Introduction AGNandtheirenvironmentuptoseveralhundredkpc,cangive a usvaluableinformationonthenatureofthegeneralAGNpop- [ Since the discovery of Active Galactic Nuclei (AGN), signif- ulation as well as on different properties of each AGN sub- icant effort has been put in the attempt to reveal their nature. 2 type. In addition, the availability nowadays of large, automati- v Nowadays, we are certain that the accretion of material into a callyconstructed,galaxycatalogues,liketheSDSS,canprovide 4 centrally located massive black hole (MBH) is responsible for the necessary statistical significancefor these type of analyses. 8 the detected excess emission in the AGN’s spectra and such However,greatcautionshouldbetakenwheninterpretingresults 0 black holes do exist in all elliptical galaxies and spiral galaxy basedonlargedatabases,sincethelargerthesamplesizetheless 4 bulges(KormendyandRichstone1995;Magorrianetal.1998), controlusuallyonehasonthespectralandotherdetailsofthein- 1. includingourown(e.g.Melia&Falcke2001).However,westill dividualgalaxyentries.Itcouldthenbedifficulttoattempttoad- 1 lackacompleteunderstandingofthevariousaspectsofactivity, dressimportantquestions,suchas:DotheUnificationparadigm 1 for example the triggering mechanism and the feeding of the explainsallcasesoftype1andtype2AGN?Whichisthetrue 1 blackhole,thephysicalpropertiesoftheaccretiondiskandthe connectionbetweengalaxyinteractions,star formationandnu- : obscuring torus predicted by the unified scheme (Antonucciet v clear activity? What is the lifetime of these phenomena? How al. 1993), the origin of jets in radio loud objects, the connec- i do LINERs fit in the general picture and can all be considered X tionwithstarformationandtheroleoftheAGNfeedback.Even AGN?DoevolutionarytrendsaffecttheAGNphenomenology? r theexactmechanismthatproducestheobservedIR,X-ray,and etc. a gamma-rayemission,isstillonlypartiallyunderstood.Theuni- ficationmodelitself,althoughsuccessfulinmanycases,hasnot beenabletofullyexplainalltheAGNphenomenology(among 1.1.TriggeringanAGNevolutionarysequence? others,the roleof interactionsoninducedactivity;Koulouridis etal.2006a,bandreferencestherein). Despite observational difficulties and limitations, there have The lack of detailed knowledgeof key aspects of the AGN been many attempts, based on different diagnostics, to inves- mechanismleavesuswithmanyscatteredpiecesofinformation. tigate the possible triggering mechanisms of nuclear activity. Theoryisunableinmostcasestoexplainobservations,andob- MostagreethattheaccretionofmaterialintoaMBH(Lynden- servationsstillcannotclearlyresolvethegalacticnucleitocon- Bell1969)isthemechanismresponsiblefortheemission,butit firmtheories.Radio-loudandradio-quietAGN,QSOtypeIand is still necessary to understand the feeding mechanism of the II, Sy1 and Sy2 galaxies, LINERs, transition galaxies between black hole. It is known and widely accepted that interactions different states (TOs) and starburst galaxies, are some of the between galaxies can drive gas and molecular clouds towards pieces of the puzzle that we are called to unify. Examination theirnucleusinitiatinganenhancedstarformation(e.g.Lietal. of the properties of the host galaxies of the different types of 2008;Ellisonetal.2008;Ideueetal.2012).Manyalsobelieve 1 Koulouridisetal.:NeighboursofSeyfertGalaxies. that the same mechanism could give birth to an active nucleus 1.2.Thiswork (e.g.Umemura1998;Kawakatuetal.2006;Ellisonetal.2011; Silvermanetal.2011). Thispaperisthethirdinaseriesof3-dimensionalstudiesofthe environmentofactivegalaxies(Koulouridisetal.2006a,b),ex- Indeed, there are several studies that conclude that there is tendingprevious2Danalyses(Dultzinetal.1999,Krongoldet anevolutionarysequencefromstarbursttoSeyfertgalaxies(e.g. al. 2002), in an effort to shed more light to the starburst/AGN Storchi-Bergmannetal.2001).Basedonthenumberandprox- connectionandtotheevolutionaryscenarioproposedinourpre- imity of close (∼<60 − 100 h−1kpc) neighbours around differ- viouspapers.Itisafollow-upspectroscopicstudyaimingatin- enttypesofactive(Sy1,Sy2andBIRG)galaxies(e.g.Dultzin- vestigatingthepossibleeffectsofinteractionsontheneighbours Hacyan et al. 1999; Krongold et al. 2002; Koulouridis et al. ofourSeyfertgalaxiesandunderstandingtheconditionsneces- 2006a,b)averyinterestingevolutionarysequencehasbeensug- saryforthedifferenttypesofactivity. gested,startingwith a closeinteractionthattriggerstheforma- In§2wewilldiscussourgalaxysamplesandwewillpresent tion of a nuclear starburst, subsequently evolving to a type 2 ourobservationsanddatareduction.Thespectroscopicanalysis Seyfert,andfinallytoaSy1.Thissequenceislikelyindependent andclassificationofthegalaxiesandtheanalysisoftheavailable ofluminosity,assimilartrendshavebeenproposedforLINERs X-rayobservationsispresentedinsection§3.Finally,insection (Krongold et al. 2003) and ULIRGs and Quasars (Fiore et al. §4wewillinterpretourresultsanddrawourconclusions.Dueto 2008 and references therein). Furthermore, numerical simula- thefactthatalloursamplesarelocal,cosmologicalcorrections tions by Hopkins et al. (2008) outlined such an evolutionary ofgalaxydistancesarenegligible.Throughoutourpaperweuse scheme for merging galaxies. The proposed activity evolution H = 100 h−1 Mpc. Note that we use the term “active” for all canfullyexplaintheexcessofstarburstsandtype2AGNinin- ◦ galaxiesthatexhibitemissionlinesin theirspectra,theirorigin teractingsystems,aswellasthelackoftype1AGNincompact beingeithernuclearactivityand/orstar-formation. groupsofgalaxies(Mart´ınezetal.2008)andgalaxypairs(e.g. Gonzalezetal.2008). In addition,poststarburststellar populationshave beenob- 2. Data servedaroundAGN(Dultzin-Hacyan&Benitez1994;Maiolino & Rieke 1995; Nelson & Whittle 1996; Hunt et al. 1997; 2.1.SampleDefinitionandPreviousResults Maiolino et al. 1997; Cid Fernandes, Storchi-Bergmann & Schmitt 1998; Boisson et al. 2000, 2004; Cid Fernandes et al. The samples of active galaxies were initially compiled from 2001,2004,2005)andinclose proximityto thecore(∼50pc). the catalogue of Lipovetskyj, Neisvestnyj & Neisvetnaya Thisfactimpliesthecontinuityofthesetwostatesandadelayof (1987). The original catalogue itself is a compilation of all 0.05-0.25Gyrbetweentheonsetofthestarburstandthelighting Seyfert galaxies known at the time from various surveys upoftheAGN(Mu¨llerSańchezetal.2008;Wild,Heckman,& and in various frequencies (optical, X-ray, radio, infrared). Charlot2010;Daviesetal.2012),whichmayreachthepeakof It includes all extended objects and several starlike objects itsactivityafter0.5-0.7Gyr(Kavirajetal.2008,2011).Davieset with absolute magnitudes lower than -24. Multifrequency data al.(2007),analyzingstarformationinthenucleiofnineSeyfert are compiled and listed, including : coordinates, redshifts, galaxiesfoundrecent,butnolongeractive,starburstswhichoc- Seyfert type (and sub-type), UBVR-photoelectric magni- curred10-300Myrago.Furthermore,mostofthesestudies(e.g. tudes, morphological types, fluxes in H and [OIII]5007, β Huntetal.1997;Maiolinoetal.1997,Guetal.2001)separate JHKLN fluxes, far-IR (IRAS) fluxes, radio fluxes at 6 and type I from type II objects implying that recent star-formation 11 cm, monochromatic X-Ray fluxes in 0.3 - 3.5 and 2 - isonlypresentintypeIIobjects(seealsoColdwelletal.2009). 10 keV. All data can be found online at vizier database Supportforaninteraction-activityrelationwasrecentlyprovided (http://vizier.cfa.harvard.edu/viz-bin/VizieR?-source=VII/173). by HI observations of Tang et al. (2008), who found that 94% AbouthalfofthelistedSeyfertgalaxiescanalsobefoundinthe of Seyfert galaxies in their sample were disturbed in contrast IRAScatalogueandthusareIRselected. to their control sample (where only 19% were disturbed), but Dultzin-Hacyan et al. (1999) selected from the catalogue seealsoGeorgakakisetal.(2009)andCisternasetal.(2011)in two volume limited and complete samples, consisting of 72 the AEGIS and cosmossurveysrespectively.We pointoutthat Sy1 and 60 Sy2, to study their circumgalactic environment.In a great theoretical success of the starburst/AGN connection is Koulouridis et al. (2006a), we used the same samples in order the quenchingof the induced star formationby the AGN feed- to verify their results, using in addition redshift data from the back, which can explain the formation of red and dead ellipti- CFA2andSSRSsurveysandourowndeeperspectroscopicob- cal galaxies (e.g. Springel et al. 2005a; Di Matteo et al. 2005; servations. Our samples were limited in the area of these two Khalatyanetal.2008).Recentobservationalstudiesandsimula- surveys (48 Sy1 and 56 Sy2) but were tested for consistency tionshaveshownthatAGNionizedoutflowsmaycarryenough with the original ones. In both studies, well selected control energytoceasestarformationinthehostgalaxy(e.g.Krongold samples(sameredshift,diameterandmorphologydistributions) et al. 2007, 2009; Blustin et al. 2008; Hopkins & Elvis 2010; wereusedforthecomparison. Novak,Ostriker&Ciotti2011;Cano-D´ıazetal.2012;Zubovas UsingtheCfA2andSSRSredshiftcatalogues,wesearched & King 2012). In addition, the correlation of morphologiesof forneighbourswithinaprojecteddistanceD≤100h−1kpcand thehostgalaxieswiththenuclearactivitytypecanalsoleadus aradialvelocityseparationδu≤600km/secandwefoundthat: toapossibleAGNevolutionarysequence(Mart´ınezetal.2008). We stress that the proposed evolutionary scenario does not – The Sy1 galaxies and their control sample show a similar invalidatetheunificationscheme.Itimpliesthattheorientation (consistent within 1σ Poisson uncertainty) fraction of ob- ofthetoruscandeterminetheAGNphenomenologyonlyatspe- jectshavingatleastonecloseneighbour. cificphasesoftheevolutionarysequence.Inparticular,thisprob- – ThereisasignificantlyhigherfractionofSy2galaxieshav- ablyoccurswhentheobscuringmolecularcloudsformthetorus, inganearneighbour,especiallywithinD≤75h−1kpc,with beforebeingcompletelysweptaway. respecttoboththeircontrolsampleandtheSy1galaxies. 2 Koulouridisetal.:NeighboursofSeyfertGalaxies. – Thelarge-scaleenvironmentofSy1galaxies(D=1h−1Mpc Basedontheabove,weadoptedthefollowingclassification and δu ≤ 1000km/sec)is denser than that of Sy2 galaxies, scheme: althoughconsistentwiththeirrespectivecontrolsamples. – galaxieswithnoemissionlinesareconsideredtobenormal Inordertoinvestigatewhetherfainterneighbours,thanthose foundintherelativelyshallowCFA2andSSRScatalogues,ex- – galaxies with emission lines are active, meaning that they istaroundourAGNsamples,weobtainedourownspectroscopic exhibitnuclearor/andstarformingactivity. observationsof all neighbourswith mB∼<18.5 and D ≤ 75 h−1 kpc for a random subsample of 22 Sy1 and 22 Sy2 galaxies. Fluxratiosfortheemissionlinesmentionedabovehavebeen We found that the percentage of both Sy1 and Sy2 galaxies measured after subtractingthe host galaxycontaminationfrom thathaveacloseneighbourincreasescorrespondinglybyabout each spectrum. We disentangle the spectral contribution of the 100%whenwe descentfrommB∼<15.5to mB∼<18.5.Thesere- hostgalaxyfromtheobservedspectrabyusingthestellar pop- sults imply that the originally found difference between Sy1 ulationsynthesiscodeSTARLIGHT3.Spectraprocessingandfits and Sy2 persists even whenaddingfainter neighboursdown to were carried in the same fashion as described in section 3.1 δm∼<3, which correspond to a magnitude similar to the Large of Leoń-Tavareset al. (2011).For a detailed description of the MagellanicCloud. STARLIGHT codeanditsscientificresults,werefertothepapers For the purposes of the present study we analyzed spectra oftheSEAGalcollaboration(Cid-Fernandesetal.2005,Mateus ofalltheneighboursaroundtheaforementionedsubsamplesof etal.2006;Asarietal.2007;Cid-Fernandesetal.2007). the 22Sy1& 22 Sy2respectively.InTable 1 and2we present AlthoughitispossibletodistinguishbetweenaSFGgalaxy the names, celestial coordinates,O magnitudes1 and red- and an AGN using only the [NII]/H ratio, we cannot distin- MAPS α shiftsoftheSy1andSy2galaxieswhichhaveatleastoneclose guish between a low ionization (LINER) and a high ionization neighbour(withinδu < 600km/sec).Notethatwehavekeptthe (Seyfert)AGNgalaxy.Wehavealsomeasured[OI](λ = 6300) originalneighboursenumerationofthepreviouspapers(forex- whenpossible,asanextraindicatorofAGNactivity.However, ample,in table 2, NGC1358hasonlyneighbour2, since 1 had theweaknessofthelineinmostcasesdidnotallowfurtheruse δu>600km/sec). ofitinaseparateBPTdiagram. In Fig.1a we plot the line ratios log([OIII]/H ) versus β log([NII]/H ) (BPT diagram) for those neighbours of Seyfert α 2.2.SpectroscopicObservations galaxiesforwhichwehaveobtainedthefullspectrum4.Wealso Wehaveobtainedspectroscopicdataofalltheneighbourgalax- plotthe Kauffmannetal. (2003a)separationlinebetweenSFG ies in our samples in order to classify their type of activity. andAGNgalaxies,givenby: Optical spectra were taken with the Boller & Chivens spec- 0.61 trograph mounted on the 2.1m telescope at the Observatorio log([OIII]/H )= +1.3, Astrono´mico Nacional in San Pedro Ma´rtir (OAN-SPM). β (log([NII]/Hα)−0.05 Observations were carried out during photometric conditions. andthecorrespondingoneofKewleyetal.(2001): Allspectrawereobtainedwitha2′.′5slit.Thetypicalwavelength range was 4000-8000 Å and the spectral resolution R=8Å. 0.61 log([OIII]/H )= +1.19. Spectrophotometricstandardstarswereobservedeverynight. β (log([NII]/H )−0.47 The data reduction was carried out with the IRAF2 α package following a standard procedure. Spectra were bias- we also plot in Fig.1b the line ratios log([OIII]/H ) vs β subtractedandcorrectedwith domeflat-field frames.Arc-lamp log([SII]/H ).Qualitatively,thesameresultsasthosepresented α (CuHeNeAr) exposures were used for wavelength calibration. in Fig.1a are repeated here as well. The dividing line is given Allspectracanbefoundattheendofthepaper(Fig.3). by Kewley at al. (2006). However, we do not have the respec- tivelineofKauffmannetal.(2003a),asitisnotavailableinthe literature, and thus we cannotseparate pure starforminggalax- 2.3.AnalysisandClassificationMethod iesfromcompositeobjects.Sincethemeasurementofthe[SII] In this section we present results of our spectroscopic obser- doubletbearsingeneralgreatererrors,wewilldrawourresults vations of all the neighbours with D ≤ 100 h−1 kpc and basedonthe[NII]forbiddenline. mOMAPS∼<18.5forthesamplesofSy1andSy2galaxies.Wehave Wecannowclassifyourobjectsinthefollowingcategories: alsousedSDSSspectrawhenavailable. – SFG(StarformingGalaxies):alltheobjectswhicharefound Our aim was to measure six emission lines: H λ4861, β belowthelineofKaufmannetal. H λ6563, [NII] λ6583, [OIII] λ5007, [SII] λ6716 and [SII] α – AGNgalaxies:theobjectswhicharefoundabovethelineof λ6731, in order to classify our galaxies, using the Baldwin, Kewleyetal. Phillips&Terlevich(1981,hereafterBPT)diagrams.Notethat – TOs(transitionobjects):theonesthatarefoundbetweenthe itwasnotpossibletomeasuretheH and[OIII]emissionlines β twolinesandexhibitcharacteristicsofbothanactivenucleus inESO545-G013N1andthusweclassifieditusingonly[NII] andastarburst. andH (Stasin´skaetal.2006). α Wechoosetocallallgalaxieswithprominentemissionlines, 1 O (blue) POSS I plate magnitudes of the Minnesota Automated thatdonotshowAGNactivity,SFGgalaxies.Wedonotattempt Plate Scanner (MAPS) system. We use O magnitudes because MAPS Zwickymagnitudeswerenotavailableforthefainterneighbours, and todividethestarforminggalaxiesintomoresubcategoriessince weneededahomogeneousmagnitudesystemforallourobjects. such a categorization appears to be highly subjective and de- 2 IRAFisdistributedbyNationalOpticalAstronomyObservatories pendsontheappliedmethodology(e.g.Knapen&James,2009). operated by the Association of Universities for Research in Astronomy,Inc.undercooperativeagreementwiththeNationalScience 3 http://starlight.ufsc.br/ Foundation. 4 Wehaveexcludedtwomergingneighbours(UGC7064) 3 Koulouridisetal.:NeighboursofSeyfertGalaxies. 3. Resultsandanalysis. 3.1.Activityoftheneighbours. (a) Inthissectionwediscussinmoredetailtheresultsofourspec- 1 troscopy and classification. We have excluded from our analy- sisaSy2galaxywithmultiplenuclei,sincealthoughitqualifies asAGNwithaclose(merging)neighbour,theindividualnuclei arenotresolvedbyourspectroscopy.Wehavealsoexcludedthe mergingneighbourofUGC7064,sincethepropertiesofitstwo 0 nucleiaremoreaffectedbytheirmutualinteractionthanbytheir neighbouringSeyfert.Wecandrawourfirstresultsforeachsam- ple separatelyinspectingTable 3. Fromthe analyzed15neigh- bours of Sy1 only 4 are normal galaxies, while 8 of them are SFGs, 2 are classified as TOsand oneis classified as an AGN. SimilarresultsholdfortheneighboursofSy2galaxies.4outof -1 13neighboursdonotshowactivity,6areSFGsand3areTOs. Kauffmann et al. (2003a) Therefore,atleast 70%of the neighbours,within 100 h−1 kpc, ------ Kewley et al. (2001) ofbothtypeofSeyfertgalaxiesareactive.Weshouldnotehere -2 -1 0 1 that Ho et al. (1997), studying a magnitude limited sample of galaxies(B ≤12.5),cameupwithasimilarhighpercentageof T activity(86%).However,theresultsofoursampleoffaintneigh- bourscannotbedirectlycomparedwiththoseofHoetal.dueto thebrightermagnitudelimitofthelatter. (b) We can extract one of the most interesting results of our 1 analysisbyexaminingFig.1,i.e.theneighboursofSy2galaxies have systematically larger values of [OIII]/H than the neigh- β boursofSy1galaxies.Especiallyforthosegalaxiesthatexhibit onlystar-formation,theratio[OIII]/Haismainlyanindicatorof theirionizationlevel,whichinitsturnisanindicatorofmetallic- ity.Furthermore,metallicityiscloselyrelatedtothestellarmass 0 (M −Z relation). The average age of the stellar population ⋆ neb alsochangesalongthe[OIII]/H axis,thehigherionizedgalax- β ies having higher ratio of current to past star-formation rates (Asarietal.2007,CidFernandesetal.2009).Summarizingall oftheaboveweconcludethattheneighboursofSeyfert2galax- -1 ies show higher ionization, lower metallicity, less stellar mass and more importantly younger stellar populations than those ------ Kewley et al. (2006) of Seyfert 1 galaxies. Using a two-dimensional Kolmogorov- Smirnovtwo-sampletestwehaveverifiedthatthenullhypothe- -2 -1 0 1 sis,thatthesamplesaredrawnfromthesameparentpopulation, isrejectedata99.9%level. Fig.1. BPT classification diagrams of the neighbours of Sy1 Finally we should note how close to a composite state are and Sy2 galaxies.The neighboursof Sy2 and Sy1 galaxiesare the neighboursofactivegalaxies,in agreementwith Kewleyat indicatedbytrianglesandcrosses,respectively. al. (2006a)whoshowed thatthe starformingmembersof close pairs, lie closer to the classification line than the starforming field galaxies. We suggest that galaxies between the curves of We also classify our objects using only the [NII]/H ratio, α Kauffmannetal.(2003)andKewleyetal.(2001)migratefroma asproposedbyStasin´skaetal.(2006).Inmoredetail,we clas- purestarformingphasetoapureAGNphase.Thissuggestionis sify as AGN those objects with log([NII]/H ) > −0.2, as SFG α ofgreatimportancetoapossibleevolutionaryscenarioandwill those with log([NII]/H ) < −0.4, and as TO the rest. We find α bediscussedfurtherin§4. that it is accurate in all cases, except one (see Table 3), with the onlycaveat thatit cannotdistinguish between LINERsand Summarizingourmainresultsofthissection: Seyferts. Hence, we use this classification for ESO 545-G013 N1 forwhichwe couldnotmeasurethe H and[OIII](λ5007) β lines. – Morethan70%oftheneighboursofthetwo AGNsamples Further classification of the Seyfert galaxies in type 1 and exhibitactivity,asindicatedbyopticalspectroscopy. type2wasobtainedbydirectvisualexaminationofthespectra – Around30%oftheneighborsofSy1andSy2galaxiesshow and the broadeningof the emission lines. No broad lines were thepresenceofAGNactivity. discovered in the spectrum of the two neighboursclassified as – The neighbours of Sy2s are systematically more ionized, AGNandthereforetheyshouldbeconsideredastype2.InTable thantheneighboursofSy1s, indicatingthattheir currentto 3welistforallneighbourstheirlineratiosandthetwodifferent paststarformationrateishigher. classifications.Ascanbeobserved,inallcasesexceptNGC3786 – No broad lines (type 1 activity) were detected in the two N1,theclassificationsareabsolutelyconsistent. neighbourswhichexhibitpureAGNspectra. 4 Koulouridisetal.:NeighboursofSeyfertGalaxies. farbelowthedashedline.OneneighbourwhichliesintheAGN regime(NGC7682-N1)canbeclearlyseen.Thishasbeenclas- sifiedasaTOgalaxyintheopticalspectroscopicanalysisandis one of the three neighbours(for which XMM observationsare available, see Table 4) having an active nucleus based on optical spectroscopy.Additionalinformationon the nature of our sourcescanbe extractedfromthe hardnessratios. Twosources NGC526-N2andNGC1358-N2havehardnessratiossuggesting absorption N ≈ 1022 cm−2, consistent with the presence of a H moderatelyobscuredactivenucleus.Boththesegalaxiespresent noopticalemissionlinesandthusareclassifiedasnormal,based ontheiropticalspectra.Inotherwords,thelackofopticalemis- sion lines from the nucleus of these objects could be a result of obscuration.In addition,we should mentionhere thatin the groupof objectswith an X-ray observation,all galaxiesclassi- fiedas“normal”throughopticalspectroscopypresentanX-ray detection,possiblyalsoindicatingthepresenceofnuclearactiv- ity. In contrast, all SFG galaxies except one in the X-ray sub- sampledonotshowanX-raydetection. WeshouldnoteherethatunobscuredlowaccretionrateSy2 objectsand/orlow luminosityAGN, where the NLR cannotbe Fig.2.TheX-ray(0.2-12keV)tooptical(B-band)fluxdiagram detectedbymeansofopticalspectroscopy,orevenX-raybina- forboththeAGNtargets(solidcircles)andtheneighbors(open ries, may account for the X-ray detection of unobscured ”nor- circles). The triangles (upperlimits) denote the neighborswith mal”galaxies.Thisanalysisthereforeimpliesthatthetotalfrac- noX-raydetection.Theupper,lowersolidlineandthedashline tionof neighboursofAGN thatshowactivity,basedonoptical correspondto f /f =+1,−1,−2respectively. spectroscopy,isatleast70%andpossiblyquitehigher.Thismat- X B terwillbefullyaddressedinfuturework. 3.2.TheXMM-Newtonobservations 4. Discussion&Conclusions We have also exploredwhether the neighboursshow X-rayac- tivity, using the XMM public archive. We find that 13 target Basedonopticalspectroscopy,wehavefoundthatthelargema- fields have been observed by XMM. However, some of them jority(> 70%)ofcloseneighboursofAGN(beingSy1orSy2) areverybrightandhavebeenobservedinpartialwindowmode, showactivity,mostlyenhancedstar-formationbutAGNaswell. renderingtheobservationsincenteroftheField-of-Viewunus- Furthermore,the close neighboursof Sy1 galaxies, being SFG able(NGC5548,NGC863,1H1142-178,NGC7469).Thelistof or AGN,are less ionizedand thusseem to be a different,more theremainingobservations(13neighboursand9centralSeyfert evolved,populationthanthoseofSy2s. galaxies)isshowninTable4,inwhichwepresentX-rayfluxes In addition, our X-ray analysis of a subsample of neigh- for the detections as well as upper limits for the non-detected bours with public XMM observations showed that the neigh- sources.Thefluxeshavebeentakenfromthe2XMMcatalogue bours which are classified as ”normal” based on optical spec- (Watson et al. 2009). The fluxes refer to the total 0.2-12 keV troscopy, might have an active core, since all of them are X- bandforthePNdetectororthecombinedMOSdetectorsinthe raydetected,whiletwooutoffiveappeartohaveamoderately case wherePN fluxesarenotavailableand areestimatedusing obscured active nucleus. On the contrary, the pure star form- aphotonindexofΓ = 1.7andanaverageGalacticcolumnden- ing neighbours do not show any X-ray emission, down to the sityofN = 3×1020 cm−2.Luminositieswereestimatedusing fluxlimitoftheavailableobservations.Fromboth,opticalspec- H the same spectral parameters. In the same table we quote the troscopyandX-rayobservations,itbecomesclearthatthefrac- 2XMMhardnessratios,derivedfromthe1-2keVand2-4.5keV tionof neighbours,within 100h−1 Mpc,of AGNorBIRG that bands (hardness ratio-3 according to the 2XMM catalogue no- areactiveis>70%andpossiblymuchhigher. tation). The upperlimits, derivedusing theFLIXsoftware, are Sincethephysicalpropertiesoftheneighboursshouldbere- estimated following the method of Carrera et al. (2007). This flected on the state of the central AGN galaxy, we argue that provides upper-limits to the X-ray flux at a given point in the these results are in the same direction as those of our previous skycoveredbyXMMpointings.Theradiususedforderivingthe papers (Koulouridis et al 2006a,b), supporting an evolutionary upper limit was 20 or 30 arcsec depending on the presence of sequence of galaxy activity, induced by interactions, the main contaminatingnearbysources. path of which starts from inactivity and then follows the se- InFig.2wepresenttheX-raytoopticalfluxdiagram f − f quenceofstarburst,Sy2andfinallySy1phase. X B (e.g. Stocke et al. 1991). This diagram provides an idea on We now attempt to interpret our present results within the whether a galaxy may host an active nucleus. This is because aboveevolutionaryscheme.Somethingthatisnowadaysundis- AGN have enhanced X-ray emission at a given optical magni- puted is the role of interactions in the creation of a starburst. tuderelativetonormalgalaxies.Thespaceusuallypopulatedby Molecular clouds are being forced towards the galactic cen- AGNisshownbetweenthecontinuouslines.ThecentralSeyfert ter, become compressed and light up the galaxy as a starburst. galaxiesareshownasfilledpoints,butsinceX-rayfluxhasnot Despite the fact that the exact mechanism is still unknown, in beencorrectedforX-rayabsorption,anumberofabsorbedAGN the local universe an accretion rate of ∼ 0.001− 0.1M⊙/yr is galaxiesliebetweentheloweranddashedline,whiletheheavily needed in order to fuel the black hole. Theoretically this can absorbedSy2NGC7743(Akylas&Georgantopoulos2009),lie onlybeachievedbymeansofa nonaxisymmetricperturbation 5 Koulouridisetal.:NeighboursofSeyfertGalaxies. whichinducesmassinflow.Suchperturbationsareprovidedei- can be accessed at http://aps.umn.edu/). The STARLIGHT therby barsorby interactions.Whicheverthe mechanismmay project is supported by the Brazilian agencies CNPq, CAPES be,theresultisthefeedingoftheblackholeandtheactivation and FAPESP and by the FranceBrazil CAPES/Cofecub pro- oftheAGN phase,maybe∼ 0.5Gyr afterthe initialinteraction gramme.FundingfortheSDSSandSDSS-IIhasbeenprovided tookplace.Aninteractioncertainlypredictssuchadelay,since bytheAlfredP.SloanFoundation,theParticipatingInstitutions, after the material has piled up around the inner Linblad reso- the National Science Foundation, the U.S. Department of nance,producingtheStarburst,itcanbechanneledtowardsthe Energy,theNationalAeronauticsandSpaceAdministration,the nucleus by loosing significant amounts of angular momentum, Japanese Monbukagakusho, the Max Planck Society, and the aprocesswhichisnotinstantaneous.Therefore,adelayshould HigherEducationFundingCouncilforEngland.TheSDSSWeb exist between the pure starformingand AGN phase, where ac- Siteishttp://www.sdss.org/. tive nucleus and circumnuclear starburst coexist. In this initial phase, the nucleus is heavily obscured by the still starforming molecularcloudsanditcanbeobservedasatransitionstageof References compositeSy2-starburstobjects. The most probable manner for the AGN to dominate is to Akylas,A.,&Georgantopoulos,I.2009,A&A,500,999 eliminatethestarburst,possiblybytheAGNoutflowsorbyra- Antonucci,R.1993,ARA&A,31,473 diationpressure.Outflowsfromthecorehaveenoughenergyto Asari,N.V.,CidFernandes,R.,Stasin´ska,G.,Torres-Papaqui,J.P.,Mateus,A., dissipatethematerialarounditandthussuffocatestarformation Sodre´,L.,Schoenell,W.,&Gomes,J.M.2007,MNRAS,381,263 Baldwin,J.A.,Phillips,M.M.,&Terlevich,R.,1981,PASP,93,5 (e.g. Krongold et al. 2007, 2009; Blustin et al. 2008; Hopkins Boisson,C.,Joly,M.,Moultaka,J.,Pelat,D.,&SeroteRoos,M.2000,A&A, &Elvis2010;Novak,Ostriker&Ciotti2011;Cano-D´ıazetal. 357,850 2012;Zubovas&King2012). Boisson,C.,Joly,M.,Pelat,D.,&Ward,M.J.2004,A&A,428,373 Thiscouldalsotakesometimeandasthestarburstfades,the Cabanela,J.E.,Humphreys,R.M.,Aldering,G.,etal.2003,PASP,115,837 Cano-D´ıaz,M.,Maiolino,R.,Marconi,A.,etal.2012,A&A,537,L8 Seyfert 2 state starts dominating, to be followed at the end by Carrera,F.J.,Ebrero,J.,Mateos,S.,etal.2007,A&A,469,27 atotallyunobscuredSy1state,possibly∼ 1Gyraftertheinitial CidFernandes,R.J.,Storchi-Bergmann, T.,&Schmitt,H.R.1998,MNRAS, interaction. 297,579 Thetimeneededfortype1activitytoappearshouldbelarger CidFernandes, R.,Heckman, T.,Schmitt, H.,Delgado, R.M.G.,&Storchi- Bergmann,T.2001,ApJ,558,81 thanthetimescaleforanunboundcompaniontoescapefromthe CidFernandes,R.,Gu,Q.,Melnick,J.,Terlevich,E.,Terlevich,R.,Kunth,D., closeenvironment,orcomparabletothetimescaleneededforan RodriguesLacerda,R.,&Joguet,B.2004,MNRAS,355,273 evolvedmerger(∼1Gyr,seeKrongoldetal.2002). CidFernandes, R.,Gonza´lez Delgado, R.M.,Storchi-Bergmann, T.,Martins, Alternatively,thereisapossibilitythattheneighboursofSy1 L.P.,&Schmitt,H.2005,MNRAS,356,270 galaxies are systematically more massive and that their older CidFernandes,R.,Asari,N.V.,Sodre´,L.,etal.2007,MNRAS,375,L16 CidFernandes,R.,etal.2009,RevistaMexicanadeAstronomiayAstrofisica stellarpopulationisduetodownsizing,i.e.moremassivegalax- ConferenceSeries,35,127 ieshaveevolvedearlier,whilelessmassiveonesexhibitmorere- Cisternas,M.,Jahnke,K.,Inskip,K.J.,etal.2011,ApJ,726,57 centstarformationandthusyoungerstellarpopulation.However, Coldwell,G.V.,Lambas,D.G.,So¨chting,I.K.,&Gurovich,S.2009,MNRAS, there is no obviousexplanationon why more massive galaxies 399,88 Davies, R., Genzel, R., Tacconi, L., Mueller Sańchez, F., & Sternberg, A.2c. shouldbelocatedpreferentiallynearSy1galaxiesandnotSy2. 2007,TheCentralEngineofActiveGalacticNuclei,373,639 Thecombinationofbothdownsizingandtheinteractiondriven Davies, R., Burtscher, L., Dodds-Eden, K., & Orban de Xivry, G. 2012, sequence,aspresentedpreviously,canalsobeatwork. arXiv:1201.5785 Fromourpointofview,inaneverevolvinguniverseanevo- DiMatteo,T.,Springel,V.,&Hernquist,L.2005,Nature,433,604 lutionary scheme, is more probable than the original unifica- Dultzin-Hacyan,D.,&Benitez,E.1994,A&A,291,720 Dultzin-Hacyan,D.,Krongold,Y.,Fuentes-Guridi,I.,&Marziani,P.1999,ApJ, tion paradigmwhich proposesa rather static view of AGN. Of 513,L111 course, orientation could and should also play a role between Ellison,S.L.,Patton,D.R.,Simard,L.,&McConnachie,A.W.2008,AJ,135, the obscured Sy2 and Sy1 phase, when the relaxing obscuring 1877 materialformsatoroidalstructure. Ellison,S.L.,Patton,D.R.,Mendel,J.T.,&Scudder,J.M.2011,MNRAS,418, 2043 Therearestillmanyunresolvedissuesandcaveatsconcern- Fiore,F.,Grazian,A.,Santini,P.,etal.2008,ApJ,672,94 ing these suggestions, since the evolutionary sequence is not Georgakakis,A.,Coil,A.L.,Laird,E.S.,etal.2009,MNRAS,397,623 uniqueandshouldalsodependonthegeometry,thedensityand Gonza´lez, J. J., Krongold, Y., Dultzin, D., et al. 2008, Revista Mexicana de otherfactorsoftheobscuringandtheaccretingmaterial,aswell AstronomiayAstrofisicaConferenceSeries,32,170 asonthemassofthehostgalaxyanditsblackhole. Gu,Q.,Maiolino,R.,&Dultzin-Hacyan,D.2001,A&A,366,765 Ho,L.C.,Filippenko,A.V.,&Sargent,W.L.W.1997,ApJS,112,315 Hopkins,P.F.,Hernquist,L.,Cox,T.J.,&Keresˇ,D.2008,ApJS,175,356 Hopkins,P.F.,&Elvis,M.2010,MNRAS,401,7 Acknowledgments Hunt,L.K.,Malkan,M.A.,Salvati,M.,Mandolesi,N.,Palazzi,E.,&Wade,R. 1997,ApJS,108,229 EK thanks the IUNAM and INAOE, were a major part of this Ideue,Y.,Taniguchi,Y.,Nagao,T.,etal.2012,ApJ,747,42 work was completed, for their warm hospitality and the State Kauffmann,G.,Heckman,T.M.,Tremonti,C.,etal.2003,MNRAS,346,1055 Scholarships Foundation (IKY) for the post doctoral research Kaviraj,S.,etal.2008,MNRAS,388,67 funding. We also thank OAGH and OAN-SPM staff for excel- Kaviraj,S.,Schawinski,K.,Silk,J.,&Shabala,S.S.2011,MNRAS,415,3798 lent assistance and technical support at the telescopes. VC ac- Kawakatu, N.,Anabuki,N.,Nagao,T.,Umemura,M.,&Nakagawa, T.2006, ApJ,637,104 knowledges funding by CONACyT research grants 54480 and Kewley,L.J.,Heisler,C.A.,Dopita,M.A.,&Lumsden,S.2001,ApJS,132,37 15149 (Me´xico). MP acknowledges funding by the Mexican Kewley,L.J.,Geller,M.J.,&Barton,E.J.2006,AJ,131,2004 Government research grant No. CONACyT 49878-F and DD Kewley,L.J.,Groves,B.,Kauffmann,G.,&Heckman,T.2006,MNRAS,372, support from grant PAPIIT IN111610 from DGAPA, UNAM. 961 Khalatyan, A., Cattaneo, A., Schramm, M., Gottlo¨ber, S., Steinmetz, M., & ThisresearchhasmadeuseoftheUSNO-Bcatalog(Monetetal. Wisotzki,L.2008,MNRAS,387,13 2003)andtheMAPSCatalogofPOSSI(Cabanelaetal.2003) Knapen,J.H.,&James,P.A.2009,ApJ,698,1437 supported by the University of Minnesota (the APS databases Kormendy,J.,&Richstone,D.1995,ARA&A,33,581 6 Koulouridisetal.:NeighboursofSeyfertGalaxies. Koulouridis,E.,Plionis,M.,Chavushyan,V.,Dultzin-Hacyan,D.,Krongold,Y., &Goudis,C.2006a,ApJ,639,37 Koulouridis,E.,Chavushyan,V.,Plionis,M.,Krongold,Y.,&Dultzin-Hacyan, D.2006b,ApJ,651,93 Krongold,Y.,Dultzin-Hacyan,D.,&Marziani,P.2002,ApJ,572,169 Krongold, Y., Nicastro, F., Brickhouse, N. S., Elvis, M., Liedahl, D. A., & Mathur,S.2003,ApJ,597,832 Krongold,Y.,Nicastro,F.,Elvis,M.,Brickhouse,N.,Binette,L.,Mathur,S.,& Jimeńez-Bailoń,E.2007,ApJ,659,1022 Krongold,Y.,etal.2009,ApJ,690,773 Leoń-Tavares, J.,Valtaoja, E.,Chavushyan, V. H.,etal. 2011, MNRAS,411, 1127 Li,C.,Kauffmann,G.,Heckman,T.M.,White,S.D.M.,&Jing,Y.P.2008, MNRAS,385,1915 Lipovetskij, V. A., Neizvestnyj, S. I., & Neizvestnaya, O. M. 1987, SoobshcheniyaSpetsial’nojAstrofizicheskojObservatorii,55 Lynden-Bell,D.1969,Nature,223,690 Magorrian,J.,Tremaine,S.,Richstone,D.,etal.1998,AJ,115,2285 Maiolino,R.,&Rieke,G.H.1995,ApJ,454,95 Maiolino,R.,Ruiz,M.,Rieke,G.H.,&Papadopoulos,P.1997,ApJ,485,552 Melia,F.,&Falcke,H.2001,ARA&A,39,309 Monet,D.G.,Levine,S.E.,Canzian,B.,etal.2003,AJ,125,984 Mart´ınez,M.A.,DelOlmo,A.,Coziol,R.,&Perea,J.2008,RevistaMexicana deAstronomiayAstrofisicaConferenceSeries,32,164 Mateus,A.,Sodre´,L.,CidFernandes,R.,etal.2006,MNRAS,370,721 Mu¨ller Sańchez, F., Davies, R. I., Genzel, R., Tacconi, L. J., Hicks, E., & Friedrich, S. 2008, Revista Mexicana de Astronomia y Astrofisica ConferenceSeries,32,109 Nelson,C.H.,&Whittle,M.1996,ApJ,465,96 Novak,G.S.,Ostriker,J.P.,&Ciotti,L.2011,ApJ,737,26 Silverman,J.D.,Kampczyk,P.,Jahnke,K.,etal.2011,ApJ,743,2 Springel,V.,DiMatteo,T.,&Hernquist,L.2005,ApJ,620,L79 Stasin´ska,G.,CidFernandes,R.,Mateus,A.,Sodre´,L.,&Asari,N.V.2006, MNRAS,371,972 Stocke,J.T.,Morris,S.L.,Gioia,I.M.,etal.1991,ApJS,76,813 Storchi-Bergmann,T.,Gonza´lezDelgado,R.M.,Schmitt,H.R.,CidFernandes, R.,&Heckman,T.2001,ApJ,559,147 Tang,Y.-W.,Kuo,C.-Y.,Lim,J.,&Ho,P.T.P.2008,ApJ,679,1094 Umemura,M.,Fukue,J.,&Mineshige,S.1998,MNRAS,299,1123 Ve´ron-Cetty,M.-P.,Balayan,S.K.,Mickaelian,A.M.,etal.2004,A&A,414, 487 Wang,L.,&Kauffmann,G.2008,MNRAS,391,785 Watson,M.G.,Schro¨der,A.C.,Fyfe,D.,etal.2009,A&A,493,339 Wild,V.,Heckman,T.,&Charlot,S.2010,MNRAS,405,933 Zubovas,K.,&King,A.2012,ApJ,745,L34 7 Koulouridisetal.:NeighboursofSeyfertGalaxies. Table1.ThesampleofSy1galaxiesandtheirneighbours1 NAME RA DEC O z MAPS J2000.0 J2000.0 integrated NGC863 021433.5 −004600 14.58 0.0270 neighbour1 021429.3 −004605 18.25 0.0270 MRK1400 022013.7 +081220 17.07 0.0293 neighbour1 021959.8 +081045 17.25 0.0284 NGC1019 023827.4 +015428 15.02 0.0242 neighbour2 023825.4 +015807 16.28 0.0203 NGC1194 030349.1 −010613 15.38 0.0134 neighbour1 030341.2 −010425 16.99 0.0140 neighbour4 030412.5 −011134 15.75 0.0130 1H1142−178 114540.4 −182716 16.82 0.0329 neighbour1 114540.9 −182736 18.01 0.0322 neighbour2 114538.8 −182919 18.45 0.0333 MRK699 162345.8 +410457 17.21 0.0342 neighbour1 162340.4 +410616 17.59 0.0334 NGC7469 230315.5 +085226 14.48 0.0162 neighbour1 230318.0 +085337 15.58 0.0156 NGC526A2 012354.5 −350356 15.693 0.0191 neighbour1 012357.1 −350409 15.803 0.0188 neighbour2 012358.1 −350654 15.683 0.0189 neighbour3 012409.5 −350542 16.373 0.0185 neighbour4 012359.2 −350738 16.043 0.0185 NGC5548 141759.5 +250812 14.18 0.0172 neighbour1 141733.9 +250652 17.16 0.0172 NGC6104 161630.7 +354229 15.11 0.0279 neighbour1 161649.9 +354207 16.44 0.0264 (1)withinaprojecteddistanceof100h−1kpcs (2)RegionNotCoveredbyMAPSCatalog (3) CalculatedfromO ,usingrelation:O = 14.61(±1.25)+ USNO MAPS 0.11(±0.11)O ,derivedfromVe´ron-Cettyetal.(2004)Table2. USNO 8 Koulouridisetal.:NeighboursofSeyfertGalaxies. Table2.ThesampleofSy2galaxiesandtheirneighbours1 NAME RA DEC O z MAPS J2000.0 J2000.0 integrated ESO545-G013 022440.5 −190831 14.41 0.0338 neighbour1 022450.9 −190803 16.19 0.0340 NGC3786 113942.5 +315433 13.88 0.0091 neighbour1 113944.6 +315552 13.53 0.0085 UGC12138 224017.0 +080314 15.93 0.0250 neighbour1 224011.0 +075959 18.77 0.0236 UGC7064 120443.3 +311038 15.11 0.0250 neighbour1(2)2 120445.6 +311127 16.68 0.0236 neighbour1 120445.2 +311133 16.33 0.0244 neighbour2 120445.1 +310934 16.33 0.0261 IRAS00160−0719 001835.9 −070256 15.73 0.0187 neighbour1 001833.3 −065854 17.80 0.0173 ESO417-G06 025621.5 −321108 15.54 0.0163 neighbour1 025640.5 −321104 17.43 0.0163 NGC1241 031114.6 −085520 13.56 0.0135 neighbour1 031119.3 −085409 15.41 0.0125 NGC1320 032448.7 −030232 14.59 0.0090 neighbour1 032448.6 −030056 15.07 0.0095 MRK612 033040.9 −030816 15.78 0.0207 neighbour1 033042.3 −030949 16.13 0.0205 NGC1358 033339.7 −050522 13.98 0.0134 neighbour2 033323.5 −045955 14.95 0.0131 IC4553 153457.1 +233016 14.43 0.0181 neighbour1 153457.3 +233005 15.68 0.0190 NGC7672 232731.4 +122307 15.23 0.0134 neighbour1 232719.3 +122803 14.67 0.0138 NGC7682 232903.9 +033200 14.88 0.0171 neighbour1 232846.6 +033041 14.64 0.0171 NGC7743 234421.1 +095603 12.16 0.0044 neighbour3 234405.5 +100326 16.95 0.0054 (1)withinaprojecteddistanceof100h−1kpcs (2) In Koulouridis et al. 2006a neighbour 1 was an unresolved merging galaxy. In this paper we were able to obtain two distinct spectraforeachnucleus. 9 Koulouridisetal.:NeighboursofSeyfertGalaxies. Table3.Observationaldata,emissionlineratiosandclassification. NAME Neigh.No U.T.date startU.T. exp.time [OIII]/Hβ [NII]/Hα [SII]/Hα Stasin´ska1 BPT2 (dd/mm/yy) (sec) Sy1galaxies NGC863 N1 SDSS - - - - - normal normal MRK1400 N1 06/10/07 07:31 4800 0.55±0.02 0.31±0.01 0.35±0.01 SFG SFG NGC1019 N2 21/10/06 08:25 4800 0.54±0.01 0.46±0.01 0.32±0.01 TO TO NGC1194 N1 SDSS - - 0.37±0.01 0.31±0.01 0.35±0.01 SFG SFG NGC1194 N4 25/10/06 07:56 5400 0.33±0.01 0.38±0.01 0.36±0.01 SFG SFG 1H1142−178 N1 19/05/07 04:29 3000 - - - normal normal 1H1142−178 N2 21/05/07 04:16 6000 0.83±2.54 0.35±0.03 0.57±0.06 SFG SFG MRK699 N1 18/05/07 10:27 2100 0.64±0.12 0.60±0.06 0.67±0.05 TO TO NGC7469 N1 01/12/06 03:07 3600 0.30±0.05 0.37±0.01 0.29±0.01 SFG SFG NGC526A N1 08/10/07 06:39 2400 3.60±0.37 1.37±0.19 1.32±0.18 AGN AGN NGC526A N2 08/10/07 08:39 1500 - - - normal normal NGC526A N3 08/10/07 09:34 3600 0.57±0.06 0.35±0.01 0.35±0.02 SFG SFG NGC526A N4 08/10/07 07:33 3600 0.34±0.02 0.34±0.01 0.38±0.01 SFG SFG NGC5548 N1 SDSS - - 0.50±0.05 0.36±0.01 0.52±0.01 SFG SFG NGC6104 N1 18/05/07 09:37 1800 - - - normal normal Sy2galaxies ESO545-G013 N1 01/12/06 05:13 3600 - 0.37±0.01 0.37±0.02 SFG - NGC3786 N1 06/03/06 06:34 3600 1.08±0.06 0.71±0.02 0.57±0.02 AGN TO UGC12138 N1 08/10/07 02:49 3600 4.48±0.11 0.07±0.01 0.18±0.01 SFG SFG UGC7064 N1(2) 18/05/07 07:11 4200 0.25±0.02 0.38±0.01 0.15±0.01 SFG SFG UGC7064 N1 SDSS - - 3.55±0.34 1.34±0.4 0.83±0.03 AGN AGN UGC7064 N2 06/03/06 08:40 2100 0.74±0.05 0.56±0.02 0.30±0.02 TO TO IRAS00160−0719 N1 06/10/07 0.97±0.02 0.25±0.01 0.44±0.01 SFG SFG ESO417-G06 N1 06/10/07 11:08 4200 1.29±0.01 0.21±0.01 0.29±0.01 SFG SFG NGC1241 N1 30/11/06 08:00 3600 1.02±0.04 0.34±0.01 0.35±0.01 SFG SFG NGC1320 N1 25/10/06 09:38 3600 - - - normal normal MRK612 N1 29/11/06 09:44 3600 - - - normal normal NGC1358 N2 21/10/06 11:08 3600 - - - normal normal IC4553 19/05/07 09:14 5400 merger NGC7672 N1 21/10/06 05:51 3600 - - - normal normal NGC7682 N1 25/10/06 06:42 3600 1.25±0.01 0.45±0.01 0.27±0.01 TO TO NGC7743 N3 20/10/06 07:00 5400 2.27±0.03 0.07±0.01 0.24±0.01 SFG SFG (1)ClassificationbasedonStasin´skaetal.(2006) (2)ClassificationbasedontheBPTdiagrams(Baldwin,Phillips&Terlevich1981) Table4.XMMobservations. Name Neigh.No 2XMMID Opt.Class logL (0.2-12keV) Flux(0.2-12keV) X/Ooffset HR X (ergs−1) (ergcm−2s−1) (arcmin) NGC1194 N1 - SFG <39.59 <7.3×10−15 - - NGC1194 N4 - SFG <39.72 <1.1×10−14 - - NGC526A N1 J012357.0-350410 AGN 40.46 3.3×10−14 0.023 −0.28±0.09 NGC526A N2 J012358.1-350653 Normal 40.75 5.9×10−14 0.008 0.05±0.1 NGC526A N3 - SFG <39.65 <4.7×10−15 - - NGC526A N4 J012359.0-350741 SFG 39.95 9.4×10−15 0.035 −0.61±0.29 UGC12138 N1 - SFG <40.63 <2.8×10−14 - - NGC1320 N1 J032448.6-030057 Normal 39.46 1.2×10−14 0.020 −0.38±0.17 MRK612 N1 J033042.5-030949 Normal 39.59 3.4×10−15 0.060 −0.67±0.24 NGC1358 N2 J033323.3-045953 Normal 40.19 3.8×10−14 0.044 0.05±0.3 NGC7682 N1 J232846.7+033041 TO 42.04 1.30×10−12 0.026 −0.32±0.02 NGC7743 N3 - SFG <39.44 3.4×10−14 - - NGC3786 N1 J113944.3+315547 TO 39.73 2.7×10−14 0.08 −0.46±0.30 10

The Activity of the Neighbours of Seyfert Galaxies

Similar The Activity of the Neighbours of Seyfert Galaxies