XMM-Newton observations of the Seyfert 1 galaxy NGC 3227

Abstract

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 ~ 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 (~6.5 x 10²² cm^-2) larger than previously measured and covering a significant fraction (~90%) of the central source. The soft X-ray continuum is also attenuated due to the presence of ionized material (xi ~ 50-90 erg s^-1 cm) suggesting the presence of a substantial amount of gas (N_H~ 2-9 *E²¹ 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.