The Variability and Spectrum of NGC 5548 in the Extreme Ultraviolet

Details The Variability and Spectrum of NGC 5548 in the Extreme Ultraviolet The Variability and Spectrum of NGC 5548 in the Extreme Ultraviolet

Apr 1997

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1997apj...479..222m&link_type=abstract

Astrophysical Journal v.479, p.222

Astronomy and Astrophysics

Astronomy

49

Galaxies: Active, Galaxies: Individual Ngc Number: Ngc 5548, Galaxies: Seyfert, Ultraviolet: Galaxies

Scientific paper

We have measured the light curve and spectrum of NGC 5548 obtained with the Extreme Ultraviolet Explorer (EUVE) during a period when the galaxy was also intensively monitored with the Hubble Space Telescope, the International Ultraviolet Explorer, and ground-based telescopes. NGC 5548 was observed with EUVE for a total of about 20 days spread over a period of 2 months. The broadband extreme ultraviolet (EUV) light curve showed several factor of 2 variations on 0.5 day timescales and one factor of 4 decrease over 2 days. The normalized variability index was smaller than in the EUVE observation of Mrk 478. Cross-correlation of the EUV light curve with the contemporaneous ultraviolet light curve indicates that the EUV and UV/optical variations are, to within the limitations of these data, simultaneous, although the amplitude in the EUV is twice that in the UV. The shape of the EUVE spectrum is consistent with a gradual steepening from the UV through the soft X-rays. Contrary to reports by others, we do not detect any emission lines in the EUV spectrum that would arise in optically thin spectral models. We believe that the reported line detections were, in fact, due to a low-level fixed pattern in the detector background. Models of the spectrum may be constrained by the time-averaged flux in the broadband detector combined with the weakly constrained spectral shape. A thermal model best describes the EUVE spectrum and its variations.

Affiliated with

Also associated with

No associations

Rating

The Variability and Spectrum of NGC 5548 in the Extreme Ultraviolet does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with The Variability and Spectrum of NGC 5548 in the Extreme Ultraviolet, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Variability and Spectrum of NGC 5548 in the Extreme Ultraviolet will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1316663