Search Publications

Low-frequency divergent X-ray variability in the Seyfert galaxy NGC4051

Elvis, M.; Watson, M. G.; Lawrence, A. +1 more

The X-ray emission from NGC4051, a nearby low luminosity Type 1 Seyfert galaxy, exhibits variations that are both rapid and apparently quasi-periodic^1,2. Many Seyfert galaxies are variable³ but our knowledge of the form of variability has not advanced substantially since early well-resolved observations⁴ and attemp…

Fractal X-ray time variability and spectral invariance of the Seyfert galaxy NGC5506

McHardy, Ian; Czerny, Bozena

Rapid X-ray variability has long been sought after in active galactic nuclei (AGN) as an indicator of such parameters as the mass-to-energy conversion efficiency and black hole mass. Although some interesting variability information has been gained from early observations (for example see ref. 1 for a review) the faintness of AGN, combined with th…

Observations of active galaxies

Mushotzky, Richard

New information obtained by the EXOSAT satellite on the nature of the X-ray variability in AGNs is discussed. From the EXOSAT data, it is seen that many more AGNs vary on short timescales; in some cases, the character of the time variability is quantitatively and qualitatively different than expected from the flare model of the variability. Data o…