SIMBAD references

1999MNRAS.305..775P - Mon. Not. R. Astron. Soc., 305, 775-794 (1999/June-1)

Soft X-ray spectral variations of the narrow-line Seyfert 1 galaxy Markarian 766.


Abstract (from CDS):

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.

Abstract Copyright: 1999, Royal Astronomical Society

Journal keyword(s): galaxies: active - galaxies: individual: mrk 766 - galaxies: Seyfert - X-rays: galaxies

Simbad objects: 12

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