X-Ray Variability of Active Galactic Nuclei

X-ray variability of active galactic nuclei is commonplace on scales from days to years. It also occurs, although rarely, on time scales as short as 200 seconds. Both these statements must be strongly qualified by the irregularity and insensitivity of the available observations. In the X-rays we expect that we are seeing deep within the active nucleus, near what is usually taken to be a massive black hole. The X-ray variability time scales may then give us the fundamental structural length scales. We would like to review data on active galaxies, present our new data on Einstein observations of BL Lac objects, and discuss all these in terms of a statistical quantification of the observations.

[1]  K. Wood,et al.  An 80 day X-ray light curve of 3C 371 , 1982 .

[2]  D. Hutter,et al.  The detection of X-ray emission from the BL Lacertae object Markarian 180 , 1981 .

[3]  R. Mushotzky,et al.  Rapid X-ray variability in the Seyfert galaxy NGC 6814. Ph.D. Thesis - Maryland Univ. , 1981 .

[4]  R. Warwick,et al.  The variability of X-ray emission from active galaxies. , 1981 .

[5]  K. Wood,et al.  Rapid X-ray variability of PKS 2155-304. , 1980 .

[6]  M. Johnston,et al.  Seyfert Type 1 galaxies observed with the HEAO 1 scanning modulation collimator , 1980 .

[7]  J. Thorstensen,et al.  H2155–304: a highly luminous BL Lac object , 1979, Nature.

[8]  A. C. Fabian,et al.  Theories of the nuclei of active galaxies , 1979, Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences.

[9]  E. Meurs,et al.  On the identification of the high-latitude X-ray source 2A 1219+305. , 1979 .

[10]  M. Johnston,et al.  3C 273: X-ray variability, spectrum, and position. , 1979 .

[11]  M. Johnston,et al.  X-ray emitting BL Lacertae objects located by the scanning modulation collimator experiment on HEAO 1 , 1979 .

[12]  R. Giacconi,et al.  Uhuru observations of X-ray emission from Seyfert galaxies. , 1978 .

[13]  M. Rees,et al.  A qualitative study of cosmic fireballs and γ-ray bursts , 1978 .

[14]  Martin P. Ward,et al.  Seyfert galaxies as X-ray sources , 1978 .

[15]  R. Mushotzky,et al.  X-ray observations of a flare in NGC 4151 from OSO 8 , 1978 .

[16]  K. Pounds,et al.  X-ray transient source at high galactic latitude and suggested extragalactic identification , 1976, Nature.