Suzaku Results on the Obscured Low - Luminosity Active Galactic Nucleus in NGC 4258

In 2006 June, the obscured low luminosity active galactic nucleus in the nearby Seyfert 1.9 galaxy NGC 4258 was observed with Suzaku for ∼ 100 ks. Utilizing the XIS and the HXD, the nucleus emission was detected over a ∼ 2 to ∼ 40 keV range, with an unabsorbed 2–10 keV luminosity of ∼ 8×10 erg s, and varied by a factor of ∼ 2 during the observation. Its 2–40 keV spectrum is reproduced by a single power law with photon index of Γ ∼ 2.0, absorbed by an equivalent hydrogen column of ∼ 1.0 × 10 cm. The spectrum within 4 of the nucleus required also a softer thin-thermal emission, as well as an intermediate hardness component attributable to integrated point sources. A weak neutral Fe-Kα florescence line was detected at an equivalent width of ∼ 40 eV. The cold reflection component was not required by the data, with the reflector solid angle Ω seen from the nucleus constrained as Ω/2π ∼ 0.3 assuming a general case of 60 inclination. The results suggest that the cold reflecting material around the nucleus is localized along our line of sight, rather than forming a thick torus.