A Long Look at NGC 3783 with the XMM-Newton Reflection Grating Spectrometers

Kavli Affiliate: Andrew P. Rasmussen

| First 5 Authors: Ehud Behar, Andrew P. Rasmussen, Alexander J. Blustin, Masao Sako, Steven M. Kahn

| Summary:

A long 280 ks observation of the Seyfert 1 galaxy NGC 3783 with XMM-Newton is
reported. We focus on the oxygen line complex between 17 and 24 A as measured
with the RGS spectrometers. Accurate absorption column densities and emission
line fluxes are obtained. We explore several options for the geometry and
physical form of the emitting and absorbing gas. The lack of change in
ionization in the absorber despite an increase in continuum flux during the
observation restricts the high-ionization (O-K) and the low-ionization (Fe-M)
gas to distances of at least 0.5 pc and 2.8 pc, respectively, away from the
central source. Given the P-Cygni type profiles in the resonance spectral lines
and the similar velocity widths, column densities, and ionization structure
inferred separately from the emission and absorption lines, it is tempting to
relate the X-ray narrow-line emitting plasma with the X-ray absorbing gas.
Under this assumption, the scenario of dense clumped clouds can be ruled out.
Conversely, extended ionization cones (r > 10 pc) are consistent with the
observation independent of this assumption. These findings are in stark
contrast with the picture of numerous clumpy (n_e > 10^9 cm^-3) clouds drawn
recently from UV spectra, but it is consistent with the extended X-ray emission
cones observed directly in Seyfert 2 galaxies.

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