NGC 1365: A low column density state unveiling a low ionization disk wind

الأصل · EN

We present the time-resolved spectral analysis of the XMM-Newton data of NGC 1365, collected during one XMM-Newton observation, which caught this "changing-look" AGN in a high flux state characterized also by a low column density (Nₕ 10²² cm ⁻²) of the X-ray absorber. During this observation the low energy photoelectric cut-off is at about 1 keV and the primary continuum can be investigated with the XMM-Newton-RGS data, which show strong spectral variability that can be explained as a variable low Nₕ, which decreased from Nₕ 10²³ cm ⁻² to 10²² cm ⁻² in a 100 ks time-scale. The spectral analysis of the last segment of the observation revealed the presence of several absorption features that can be associated with an ionized (log ξ 2 erg cm s⁻¹) outflowing wind (vout 2000 km s⁻¹). We detected for the first time a possible P-Cygni profile of the Mgxii Lyα line associated with this mildly ionized absorber indicative of a wide angle outflowing wind. We suggest that this wind is a low ionization zone of the highly ionized wind present in NGC 1365, which is responsible for the iron K absorption lines and is located within the variable X-ray absorber. At the end of the observation, we detected a strong absorption line at E 0.76 keV most likely associated with a lower ionization zone of the absorber (log ξ 0.2 erg cm s⁻¹, Nₕ 10²² cm ⁻²), which suggests that the variable absorber in NGC 1365 could be a low ionization zone of the disk wind.