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

TL;DR

This study reports the first detection of hard X-rays above 10 keV from the Compton-thick Seyfert 2 galaxy NGC 2273 using Suzaku, revealing its complex spectrum and constraining the torus geometry.

Contribution

First broad-band spectrum of NGC 2273 obtained with Suzaku, including detection of hard X-rays and modeling of the torus geometry.

Findings

Detected hard X-rays above 10 keV from NGC 2273.

Spectrum modeled with three components: soft, reflection, and absorbed power-law.

Estimated intrinsic 2-10 keV luminosity of ~1.7x10^42 erg/s.

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 ~10 keV from NGC 2273. The broad-band spectrum is well represented by a three-component model, accompanied by both a strong iron Ka line with an equivalent width of ~ 1.8 keV 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~0.56 keV 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 ~1.5x10^24 cm^-2, has an intrinsic 2-10 keV luminosity of ~1.7x10^42 erg/s. We also apply 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 place some tentative constraints on the geometry of the putative torus in NGC2273.