XMM – Newton observations of the Seyfert 1 galaxy NGC 3227

✍ Scribed by P. Gondoin

• Publisher: Elsevier Science
• Year: 2004
• Tongue: English
• Weight: 289 KB
• Volume: 132
• Category: Article
• ISSN: 0920-5632
• DOI: 10.1016/j.nuclphysbps.2004.04.028

✦ Synopsis

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 (Γ ≈ 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 × 10 22 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 (ξ ≈ 50 -90 erg s -1 cm) suggesting the presence of a substantial amount of gas (NH ≈ 2-9 10 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.