EDP Sciences
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Volume 397, Number 3, January III 2003
Page(s) 883 - 890
Section Galactic structure and dynamics
DOI http://dx.doi.org/10.1051/0004-6361:20021574

A&A 397, 883-890 (2003)
DOI: 10.1051/0004-6361:20021574

XMM-Newton observations of the Seyfert 1 galaxy NGC 3227

P. Gondoin, A. Orr, D. Lumb and H. Siddiqui

Research and Scientific Support Department, European Space Agency - Postbus 299, 2200 AG Noordwijk, The Netherlands
(Received 1 May 2002 / Accepted 30 October 2002 )

We report on an XMM-Newton observation of the Seyfert 1 galaxy NGC 3227 performed in November 2000. The observed X-ray spectrum above 4 keV is well fitted by a hard power law continuum ( $\Gamma \approx 1.5$) and an absorption edge at 7.6 keV. An Fe K emission line with an equivalent width of 213 eV is detected at 6.4 keV. The line is narrow suggesting contribution from material in low ionization states ( <Fe XVII) relatively far from a central black hole. The continuum is strongly absorbed at soft energies by a column of neutral gas ( ${\approx}6.5 \times 10^{22}$ cm -2) larger than previously measured and covering a significant fraction ( $\approx$90%) of the central source. The soft X-ray continuum is also attenuated due to the presence of ionized material ( $\xi \approx 50{-}90$ erg s -1 cm) suggesting the presence of a substantial amount of gas ( $N_{\rm H}\approx 2{-}9 \times10^{21}$ cm -2) in the vicinity ( <0.4 pc) of the nucleus. We find that NGC 3227 exhibits significant spectral variability above 2 keV on time scales of a few ksec during the XMM-Newton observations. This short term variability is likely related to variation in the continuum emission. Comparisons with previous observations indicate that variability on timescale of a month also involves a change in the column densities of neutral absorbing material along the line of sight to the nucleus.

Key words: galaxies: individual: NGC 3227 -- galaxies: nuclei -- galaxies: Seyfert

Offprint request: P. Gondoin, pgondoin@rssd.esa.int

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