Bepposax uncovers a type-2 qso in the hyperluminous infrared galaxy iras 09104+4109

Dec, 1999
7 pages
Published in:
  • Astron.Astrophys. 353 (2000) 910
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Abstract: (arXiv)
We studied with BeppoSAX the infrared luminous galaxy IRAS 09104+4109 over a very wide X-ray band from 0.1 to 80 keV. Our observations indicate the dominance of a thermal component at energies below 8 keV, which we attribute to the free-free emission from the intracluster (IC) plasma surrounding the source. Above 10 keV we find evidence for the existence of flux in excess with respect to the free-free IC plasma emission. This, together with the marginal detection of a neutral iron line at 6.4\sim 6.4 keV, gives a strong indication for the presence of an AGN deeply buried within the source. This component is best modelled by a strongly absorbed (N_H > 5 10^{24} cm^{-2}) power-law plus unabsorbed reflection spectrum (0.1546erg/s,wellwithintherangeofquasarluminosities.OurresultsindicatethatIRAS09104+4109isindeedtheprototypeofarareclassofsources,theluminoustype2QSOs.Theassociationofthissourcewithahugecoolingflowof^{46} erg/s, well within the range of quasar luminosities. Our results indicate that IRAS 09104+4109 is indeed the prototype of a rare class of sources, the luminous type-2 QSOs. The association of this source with a huge cooling-flow of \sim 1000 M_\odot$ in the cluster, as indicated by the X-ray data, might suggest that such condition of extremely fast mass accumulation could favour the survival of a thick obscuring envelope, which would otherwise be quickly destroyed by the very luminous central source.