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

Journal Article · Sat Nov 01 00:00:00 EDT 2014 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/795/1/87· OSTI ID:22370273

Braito, V. ^[1]; Reeves, J. N.; Gofford, J.; Nardini, E. ^[2]; Porquet, D. ^[3]

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1. INAF-Osservatorio Astronomico di Brera, Via Bianchi 46, I-23807 Merate (Italy)
2. Astrophysics Group, School of Physical and Geographical Sciences, Keele University, Keele, Staffordshire ST5 5BG (United Kingdom)
3. Observatoire Astronomique de Strasbourg, CNRS, UMR 7550, 11 rue de l'Université, F-67000 Strasbourg (France)

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' active galactic nucleus in a high flux state characterized also by a low column density (N {sub H} ∼ 10{sup 22} cm{sup –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 N {sub H} that decreased from N {sub H} ∼ 10{sup 23} cm{sup –2} to 10{sup 22} cm{sup –2} in a 100 ks timescale. 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{sup –1}) outflowing wind (v {sub out} ∼ 2000 km s{sup –1}). We detected for the first time a possible P-Cygni profile of the Mg XII 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{sup –1}, N {sub H} ∼ 10{sup 22} cm{sup –2}), which suggests that the variable absorber in NGC 1365 could be a low ionization zone of the disk wind.

• OSTI ID: 22370273
• Journal Information: Astrophysical Journal, Vol. 795, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
DENSITY
GALAXY NUCLEI
IRON
K ABSORPTION
KEV RANGE
LYMAN LINES
TIME RESOLUTION
X RADIATION
X-RAY GALAXIES