Suzaku Wide-Band X-Ray Spectroscopy of the Seyfert2 AGN in NGC 4945

摘要

SuzakuobservedanearbySeyfert2galaxy,NGC4945,whichhostsoneofthebrightestactivegalacticnucleiabove20keV.CombiningdatafromthetwodetectorsaboardSuzaku,theAGNintrinsicnuclearemissionanditsreprocessedsignalswereobservedsimultaneously.Theintrinsicemissionishighlyobscuredwithanabsorbingcolumnof$$sim$$5$$ imes10^{24}$$cm$$^{-2}$$.Thespectrumbelow10keVisdominatedbyareflectioncontinuumandemissionlinesfromneutral/ionizedmaterial.AlongwithaneutralironK$$alpha$$line,aneutralironK$$eta$$lineandaneutralnickelK$$alpha$$lineweredetectedforthefirsttimefromthissource.Theneutrallinesandthecoldreflectioncontinuumareconsistentwithbothoriginatinginthesamelocation.TheComptondown-scatteredshoulderintheneutralFe-K$$alpha$$lineis$$sim10%$$influxofthenarrowcore,whichconfirmsthatthelineoriginatesfromreflection,ratherthantransmission.Thefluxoftheintrinsicemissionvariedbyafactorof$$sim2$$within$$sim20$$ks,whichrequirestheobscuringmaterialtobegeometricallythin.Broadbandspectralmodelingshowedthatthesolidangleoftheneutralreflectorislessthanafew$$ imes10^{-2} imes2pi$$.Allofthisevidenceregardingthereprocessedsignalssuggeststhatadisk-likeabsorber/reflectorisviewedfromanearedge-onangle.