On the Extended Soft X-Ray and Fe Kα Emission in NGC 1068

Abstract

The soft X-ray excess and Fe K α emission lines are widely observed in Seyfert galaxies, with their origin still in debate. We present a detailed spatially resolved image and spectral analysis of the Seyfert 2 galaxy NGC 1068 using high-resolution Chandra ACIS data. We find that the soft X-ray emission and iron emission show extended structures in the northeast and southwest directions. Especially, the soft X-ray extends predominantly in the 1 ^″ −15 ^″ (∼72 pc–1 kpc) northeast sector with a distance of at least ∼10 ^″ (∼700 pc), and its 0.5–3.0 keV flux is about ∼2/3 of that from the 1 ^″ radius circular region centered on the core of NGC 1068. We fit the soft X-ray spectra from the core and two bright blobs (∼3 ^″ , S1 and ∼1 $\mathop{.}\limits^{\unicode{x02033}}$ 5, S2 from the nucleus) as a dual-temperature plasma with two APEC models. Our analysis suggests that the extended soft X-ray emission in NGC 1068, as well as contributions to Fe K α emission from the extended region, likely originate from the interactions between the jet and the interstellar medium, offering further insights into the origin of soft X-ray excess and Fe K α emission lines in similar Seyfert sources. However, extended X-ray emission outside the ionization cone might be influenced by additional processes; future multiwavelength observations will be needed to test these possibilities.

Keywords

• Seyfert galaxies
• Active galactic nuclei
• X-ray active galactic nuclei