Far Ultraviolet Spectroscopic Explorer Spectroscopy of Absorption and Emission Lines from the Narrow-Line Seyfert 1 Galaxy NGC 4051
Abstract
We present three Far Ultraviolet Spectroscopic Explorer (FUSE) observations of the narrow-line Seyfert 1 galaxy NGC 4051. The most prominent features in the far-ultraviolet (FUV) spectrum are the O VI emission and absorption lines and the H I Lyman series absorption lines, which are detected up to the Lyman edge. We also identify weak emission from N III, C III, and He II. The C III line shows absorption, while none is detected in the N III and He II lines. In H I and C III we detect two main absorption systems at outflow velocities of -50+/-30 and -240+/-40 km s-1, as well as a possible third one at about -450 km s-1. These systems are consistent in velocity with the 10 absorption systems found previously in C IV, N V, and Si IV, though the individual systems are blended together in the FUV spectrum. We estimate column densities of the two main absorption systems and find that the H I column density is lower for systems with larger outflow velocity. We detect no flux or spectral variations of NGC 4051 at FUV wavelengths during three epochs spanning 1 yr. This is consistent with the optical light curve, which shows no variations between the three epochs. It is also consistent with the X-ray light curve, which shows consistent flux levels at the three epochs of the FUSE observations, although the X-ray light curve shows strong variations on much shorter timescales.
- Publication:
-
The Astronomical Journal
- Pub Date:
- May 2004
- DOI:
- 10.1086/383555
- arXiv:
- arXiv:astro-ph/0402318
- Bibcode:
- 2004AJ....127.2631K
- Keywords:
-
- Galaxies: Active;
- Galaxies: Individual: NGC Number: NGC 4051;
- Galaxies: Nuclei;
- Galaxies: Seyfert;
- Techniques: Spectroscopic;
- ultraviolet: galaxies;
- Astrophysics
- E-Print:
- 9 pages, 7 figures (5 in color), emulateapj, accepted for publication in The Astronomical Journal