BROADBAND X-RAY SPECTRA OF TWO LOW-LUMINOSITY ACTIVE GALACTIC NUCLEI NGC 1566 AND NGC 4941 OBSERVED WITH SUZAKU

We report the first broadband X-ray spectra of the low-luminosity active galactic nuclei (LLAGNs), NGC 1566 (type 1.5) and NGC 4941 (type 2), observed with Suzaku and Swift/BAT covering the 0.5-195 keV band. Both targets have hard X-ray luminosities of similar to 10(41-42) erg s(-1) in the 15-55 keV band. The spectra of the nucleus are well reproduced by a sum of partially or fully covered transmitted emission and its reflection from the accretion disk, reprocessed emission from the torus accompanied by a strong narrow iron-Ka line, and a scattered component (for NGC 4941). We do not significantly detect a broad iron-K alpha line from the inner accretion disk in both targets, and obtain an upper limit on the corresponding solid angle of Omega/2 pi < 0.3 in NGC 1566. The reflection strength from the torus is moderate, Omega/2 pi = 0.45(-0.10)(+0.13) in NGC 1566 and Omega/2 pi = 0.64(-0.27)(+0.69) in NGC 4941. Comparison of the equivalent width of the narrow iron-K alpha line with a model prediction based on a simple torus geometry constrains its half-opening angle to be theta(oa) similar or equal to 60 degrees-70 degrees in NGC 4941. These results agree with the obscured AGN fraction obtained from hard X-ray and mid-infrared selected samples at similar luminosities. Our results support the implication that the averaged covering fraction of AGN tori is peaked at L similar to 10(42-43) erg s(-1) but decreases toward lower luminosities.