NOAO > Library > NOAO Preprint Series > Preprint 893
|
NOAO > Library > NOAO Preprint Series > Preprint 893 |
|
Author(s): Brotherton, M.S., Green, R.F., et al.
Title: Far Ultraviolet Spectroscopic Explorer
Observations of the Seyfert 1.5 Galaxy
NGC 5548 in a Low State
Abstract:
We present far-ultraviolet spectra of the Seyfert 1.5 galaxy NGC 5548
obtained in 2000 June with the Far Ultraviolet Spectroscopic Explorer
(FUSE). Our data span the observed wavelength range 915--1185 Angstroms
at a resolution of 20 km/s. The spectrum shows a weak continuum and
emission from O VI, C III, and He II. The FUSE data were obtained when
the AGN was in a low state, which has revealed strong, narrow O VI
emission lines. We also resolve intrinsic, associated absorption lines of
O VI and the Lyman series. Several distinct kinematic components are
present, spanning a velocity range of 0 to -1300 km/s relative to
systemic, with kinematic structure similar to that seen in previous
observations of longer wavelength ultraviolet (UV) lines. We explore the
relationship between the far-UV absorbers and those seen previously in the
UV and X-rays. We find that the high-velocity UV absorption component is
consistent with being low-ionization, contrary to some previous claims,
and is consistent with its non-detection in high-resolution X-ray spectra.
The intermediate velocity absorbers, at -300 to -400 km/s, show H I and O
VI column densities consistent with having contributions from both a
high-ionization X-ray absorber and a low-ionization UV absorber. No
single far-UV absorbing component can be solely identified with the X-ray
absorber.
Date Received:
September 28, 2001
Publication Info:
ApJ 565:800-807
Telescopes:
None
Downloadable version (3489 Kb PDF)
|
NOAO > Library > NOAO Preprint Series > Preprint 893 |
|