Page, MJ; Carrera, FJ; Mittaz, JPD; Mason, KO; (1999) Soft X-ray spectral variations of the narrow line Seyfert l galaxy Markarian 766. Monthly Notices of the Royal Astronomical Society , 305 (4) 775 - 794. 10.1046/j.1365-8711.1999.02489.x.
|PDF - Requires a PDF viewer such as GSview, Xpdf or Adobe Acrobat Reader|
The X-ray variability of the narrow-line Seyfert 1 galaxy Markarian 766 is studied using nine ROSAT PSPC data sets. The spectrum is well described by a power law combined with a blackbody (kT ∼ 70 eV) soft excess. Examination of flux ratio changes and variability amplitude in three X-ray bands shows that the power-law component varies continuously on time-scales of ∼ 5000 s and is steeper when it is brighter. In contrast, variability of the soft excess is not detected. Spectral modelling of 31 spectra from different observations and at a range of count rates is also consistent with a picture in which the power law is steeper when it is brighter, and in which the soft-excess component does not vary. The power-law variability can be explained if the power law is produced by variable thermal or non-thermal Comptonization of soft photons. This behaviour is similar to that of Galactic black hole candidates in the low state. The X-ray and multiwavelength properties of Markarian 766 are shown to be very similar to those of other narrow-line Seyfert 1s. This may mean that the rapid X-ray variability seen in other narrow-line Seyfert 1s may also not originate in their strong soft-excess components.
|Title:||Soft X-ray spectral variations of the narrow line Seyfert l galaxy Markarian 766|
|Open access status:||An open access version is available from UCL Discovery|
|Additional information:||© 1999 RAS Definitive versions of articles pre-2013 are available at http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1365-2966, now published by http://mnras.oxfordjournals.org|
|Keywords:||galaxies, galaxy, X-ray|
|UCL classification:||UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Space and Climate Physics|
View download statistics for this item
Activity - last month
Activity - last 12 months
Archive Staff Only: edit this record