Unveiling the nature of INTEGRAL objects through optical spectroscopy. IV. A study of six n

We present further results from our ongoing optical spectrophotometric campaign at the Astronomical Observatory of Bologna in Loiano (Italy) on unidentified hard X-ray sources detected by INTEGRAL. We observed spectroscopically the putative optical counter

Astronomy&Astrophysicsmanuscriptno.aa5111(DOI:willbeinsertedbyhandlater)

February5,2008

UnveilingthenatureofINTEGRALobjectsthroughopticalspectroscopy.IV.AstudyofsixnewhardX–raysources

N.Masetti1,L.Bassani1,A.Bazzano2,A.J.Bird3,A.J.Dean3,A.Malizia1,L.Norci4,E.Palazzi1,A.D.

Schwope5,J.B.Stephen1,P.Ubertini2andR.Walter6

arXiv:astro-ph/0604482v2 16 Jun 2006

1

2

3

456

INAF–IstitutodiAstro sicaSpazialeeFisicaCosmicadiBologna,ViaGobetti101,I-40129Bologna,Italy(formerlyIASF/CNR,Bologna)

INAF–IstitutodiAstro sicaSpazialeeFisicaCosmicadiRoma,ViaFossodelCavaliere100,I-00133Rome,Italy(formerlyIASF/CNR,Rome)

SchoolofPhysics&Astronomy,UniversityofSouthampton,Southampton,Hampshire,SO171BJ,UnitedKingdom

SchoolofPhysicalSciences,DublinCityUniversity,Glasnevin,Dublin9,RepublicofIrelandAstrophysikalischesInstitutPotsdam,AnderSternwarte16,D-14482Potsdam,GermanyINTEGRALScienceDataCentre,Chemind’Ecogia16,CH-1290Versoix,Switzerland

Received28February2006;accepted21April2006

Abstract.WepresentfurtherresultsfromourongingopticalspectrophotometriccampaignattheAstronomicalObservatoryofBolognainLoiano(Italy)onunidenti edhardX–raysourcesdetectedbyINTEGRAL.Weob-servedspectroscopicallytheputativeopticalcounterpartsoftheINTEGRALsourcesIGRJ00234+6141,IGRJ01583+6713,IGRJ06074+2205,IGRJ13091+1137andIGRJ20286+2544.We ndthatthe rsttwoareGalacticobjects,namelyaCataclysmicVariableatadistanced~300pcandaBe/XtransientHigh-MassX–rayBinary(HMXB)locatedat~6.4kpc,respectively,whereasthelastoneisidenti edwithMCG+04-48-002,aStarburst/Hiigalaxyatredshiftz=0.013hidingaSeyfert2nucleus.WeidentifyIGRJ13091+1137asthe(likelySeyfert2type)activenucleusofgalaxyNGC4992,whichweclassifyasanX–rayBright,OpticallyNormalGalaxy;thisisthe rstexampleofthistypeofobjecttobedetectedbyINTEGRAL,andoneoftheclosestofthisclass.Wemoreovercon rmthepossibleBe/XnatureofIGRJ06074+2205,andweestimateittobeatadistanceof~1kpc.Wealsoreexaminethespectrumofthez=0.087ellipticalradiogalaxyPKS0352 686,thepossiblecounterpartoftheINTEGRALsourceIGRJ03532 6829,andwe ndthatitisaBLLac.Physicalparametersforthesesourcesarealsoevaluatedbydiscussingour ndingsinthecontextoftheavailablemultiwavelengthinformation.Theseidenti cationsfurtherstresstheimportanceofINTEGRALinthestudyofthehardX–rayspectrumofActiveGalacticNuclei,HMXBsandCataclysmicVariables.

Keywords.Galaxies:Seyfert—BLLacertaeobjects:individual:PKS0352 686—Stars:novae,cataclysmicvariables—X–rays:binaries—Techniques:spectroscopic—X–rays:individuals:IGRJ00234+6141;IGRJ01583+6713;IGRJ03532 6829(=PKS0352 686);IGRJ06074+2205;IGRJ13091+1137(=NGC4992);IGRJ20286+2544(=MCG+04-48-002)

1.Introduction

SinceitslaunchinOctober2002,theINTEGRALsatellite(Winkleretal.2003)isrevolutionizingourknowledgeofthehardX–rayskyabove20keVintermsofbothsensi-tivityandpositionalaccuracyofthedetectedhardX–raysources.Indeed,thankstothecapabilitiesoftheISGRI

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