1998/06/30 by I. M. George, R. F. Mushotzky, T. J. Turner +4
Physics and Astronomy · #Absorption (acoustics) #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Cosmic Phenomena #Emission spectrum #Galaxies: Formation, Evolution, Phenomena #Galaxy #Ion #Ionization #Optics #Physics #ROSAT #Spectral line #astro-ph
paper · pdf · doi:10.1086/306477
Accepted for publn in ApJ. LaTeX, 38 pages (inc 7 figs) & a PS file w/ 4 tables. For full abstract and other download options, see href="http://lheawww.gsfc.nasa.gov/~george/papers/3227/abstract.html
arxiv created 1998/06/30 · openalex publication_date 1998/12/10 · arxiv updated 2016/08/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
(Abridged) We present the results from it ASCA observations of NGC 3227 along with those from a it ROSAT observation. The 0.6--10 keV continuum is consistent with a powerlaw with \Γ \∼ 1.6, flatter than that typically observed in Seyfert galaxies. Fe K-shell emission is observed with an EW and profile typical of Seyfert 1 galaxies. The it ASCA observations in 1993 reveal absorption by a screen NH,zion \≃ 3\×1021 cm-2 of ionized material with UX \≃ 0.01. Joint analysis of the it ASCA and it ROSAT data show an additional screen of neutral material instrinsic to NGC 3227 with NH,zneu \∼ few\×1020 cm-2. NGC 3227 exhibits spectral variability both within and between the observations, due to short-term variability in the continuum emission and longer-term variability in the absorption. Time-resolved spectroscopy show the continuum steepened by increased by a factor of \∼10 by the 1995 epoch, while the continuum is consistent with that observed in 1993. The 1995 data also show evidence that the warm absorber allows \∼10% of the nuclear emission to escape without attenuation.