Observations of Sy2 galaxy NGC 3281 by XMM-Newton and INTEGRAL satellites

TL;DR

This study analyzes X-ray data from XMM-Newton and INTEGRAL satellites to characterize the structure and properties of the obscuring torus in Seyfert 2 galaxy NGC 3281, revealing a clumpy, inhomogeneous torus model.

Contribution

First XMM-Newton spectrum of NGC 3281 is presented, and a clumpy torus model is proposed, challenging previous continuous torus assumptions.

Findings

Torus inclination angle ~67 degrees

Hydrogen column density ~2.08 x 10^{24} cm^{-2}

Detection of hot diffuse gas at ~590 eV

Abstract

We present here the results of our analysis of X-ray properties of Seyfert 2 galaxy NGC 3281, based on the observational data obtained by XMM-Newton and INTEGRAL within the energy ranges 0.2-12 keV and 20-150 keV, respectively. The XMM-Newton spectrum of this object is presented for the first time. We show that fitting the X-ray spectrum of this galaxy with models based on the reflection from the disc with infinite column density yields non-physical results. More appropriate fit takes into account both transmitted and reflected emission, passed through a gas-dusty torus-like structure. Keeping this in mind, to model the inhomogeneous clumpy torus, we used the MYTorus model. Hence, we propose that the torus of NGC 3281 is not continuous structure, but it consists of separate clouds, which is in a good agreement with the results of near-IR observations. Using this assumption, we found that the torus inclination angle and the hydrogen column density are 66.98^{+2.63}_{-1.34} degrees and 2.08^{+0.35}_{-0.18}x10^{24} cm^{-2}, respectively. Also, the emission of the hot diffuse gas with temperature ~590 eV and warm absorption were detected.