1999/06/03 by T. J. Turner, I. M. George, K. Nandra +1 · 9 citations
Physics and Astronomy · #Accretion (finance) #Accretion disc #Amplitude #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Galaxies: Formation, Evolution, Phenomena #Galaxy #Population #Quasar #Range (aeronautics) #Spectral index #Spectral line #astro-ph
paper · pdf · doi:10.1086/307834
11 pages, 1 figure 1 table. LaTeX with encapsulated postscript. Accepted for publication in the Astrophysical Journal. Replaced first version to fix a printing problem caused by the figure. Figure content is the same as before
arxiv created 1999/06/03 · openalex publication_date 1999/10/20 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
This paper presents a quantification of the X-ray variability amplitude for 79 ASCA observations of 36 Seyfert 1 galaxies. We find that consideration of sources with the narrowest permitted lines in the optical band introduces scatter into the established correlation between X-ray variability and nuclear luminosity. Consideration of the X-ray spectral index and variability properties together shows distinct groupings in parameter space for broad- and narrow-line Seyfert 1 galaxies, confirming previous studies. A strong correlation is found between hard X-ray variability and FWHM Hβ. A range of nuclear mass and accretion rate across the Seyfert population can explain the differences observed in X-ray and optical properties. An attractive alternative model, which does not depend on any systematic difference in central mass, is that the circumnuclear gas of narrow-line Seyfert 1 galaxies is different from broad-line Seyfert 1 galaxies in temperature, optical depth, density, or geometry.