2,897 research outputs found
Evidence for a high accretion rate as the defining parameter of Narrow-Line Seyfert 1 galaxies
X-ray spectral features which are unusually strong in many Narrow-Line
Seyfert galaxies are found to be consistent with reflection from strongly
ionized matter, providing further evidence of a high accretion rate in these
objects and offering a unique signature of that key parameter in future
observations.Comment: Contributed talk presented at the Joint MPE,AIP,ESO workshop on
NLS1s, Bad Honnef, Dec. 1999, to appear in New Astronomy Reviews; also
available at http://wave.xray.mpe.mpg.de/conferences/nls1-worksho
An extended XMM-Newton observation of the Seyfert galaxy NGC 4051. II. Soft X-ray emission from a limb-brightened shell of post-shock gas
An extended XMM-Newton observation of the Seyfert I galaxy NGC 4051 in 2009
revealed a complex absorption spectrum, with a wide range of outflow velocities
and ionisation states.The main velocity and ionisation structure was
interpreted in Paper I in terms of a decelerating, recombining flow resulting
from the shocking of a still higher velocity wind colliding with the ISM or
slower moving ejecta. The high sensitivity of the XMM-Newton observation also
revealed a number of broad emission lines, all showing evidence of
self-absorption near the line cores. The line profiles are found here to be
consistent with emission from a limb-brightened shell of post-shock gas
building up ahead of the contact discontinuity. While the broad emission lines
remain quasi-constant as the continuum flux changes by an order of magnitude,
recombination continua of several H- and He-like ions are found to vary in
response to the continuum, providing an important key to scaling the ionised
flow.Comment: Accepted for publication in MNRA
X-ray reflection in the nearby Seyfert 2 galaxy NGC 1068
We use the full broad-band XMM-Newton EPIC data to examine the X-ray spectrum
of the nearby Seyfert 2 galaxy NGC 1068, previously shown to be complex with
the X-ray continuum being a sum of components reflected/scattered from cold
(neutral) and warm (ionised) matter, together with associated emission line
spectra. We quantify the neutral and ionised reflectors in terms of the
luminosity of the hidden nucleus. Both are relatively weak, a result we
interpret on the Unified Seyfert Model by a near side-on view to the putative
torus, reducing the visibility of the illuminated inner surface of the torus
(the cold reflector), and part of the ionised outflow. A high inclination in
NGC 1068 also provides a natural explanation for the large (Compton-thick)
absorbing column in the line-of-sight to the nucleus. The emission line fluxes
are consistent with the strength of the neutral and ionised continuum
components, supporting the robustness of the spectral model.Comment: 8 pages. 7 figures. Accepted for publication in MNRA
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