Abstract

According to theory, the torus of active galactic nuclei (AGN) is sustained from a wind coming off the accretion disc, and for lo w ef ficient AGN, it has been proposed that such structure disappears. Ho we v er, the e xact conditions for its disappearance remain unclear. This can be studied throughout the reflection component at X-rays, which is associated with distant and neutral material at the inner walls of the torus in obscured AGN. We select a sample of 81 AGNs observed with NuSTAR with a distance limit of D < 200 Mpc and Eddington rate λEdd ≡L bol / L Edd < 10 -3 . We fit the 3-70 keV spectra using a model accounting for a partial-co v ering absorber plus a reflection component from neutral material. We find that the existence of the reflection component spans in a wide range of black hole mass and bolometric luminosities, with only ∼13 per cent of our sample (11 sources) lacking of any reflection signatures. These sources fall in the region in which the torus may be lacking in the L-MBH diagram. For the sources with a detected reflection component, we find that the vast majority of them are highly obscured ( log N H > 23 ), with ∼20 per cent being Compton-thick. We also find an increase in the number of unobscured sources and a tentative increase on the ratio between FeKαemission line and Compton-hump luminosities toward λEdd = 10 -5 , suggesting that the contribution of the FeKαline changes with Eddington ratio.