Detection of Hard X-Rays from the Compton-Thick Seyfert 2 Galaxy NGC 2273 with Suzaku

Abstract

We have obtained a broad-band spectrum of the Compton-thick Seyfert 2 galaxy NGC 2273 with Suzaku. The spectrum reveals the first detection of hard X-rays above ∼10keV from NGC 2273. The broad-band spectrum is well represented by a three component model, accompanied by both a strong iron Kα line with an equivalent width of ∼1.8keV and several weak lines. The three component model consists of a soft component, a reflection component from cold matter, and an absorbed power law component. The soft component can be represented by thin thermal emission with kT ∼0.56keV or by a scattered component with a scattering fraction of 0.4%. Fixing the photon indices of the power law and reflection components at 1.9, we found that the power law component, heavily absorbed by gas with a column density of ∼1.5 ×10²⁴cm^-2, has an intrinsic 2--10keV luminosity of ∼1.7 ×10⁴²erg s^-1. We also applied a reflection model based on a Monte Carlo simulation, assuming a simple torus geometry. We found that the model fits the broad band spectrum well, and we placed some tentative constraints on the geometry of the putative torus in NGC 2273.