Query : 2004A&A...415..959B

2004A&A...415..959B - Astronomy and Astrophysics, volume 415, 959-969 (2004/3-1)

X-ray variability of the Narrow Line Seyfert 1 Galaxy PKS 0558-504.


Abstract (from CDS):

We present results from several XMM-Newton observations of the radio-loud Narrow-line Seyfert 1 galaxy (NLS1) PKS 0558-504. We find evidence for strong and persistent X-ray variability, both on short and long time-scales. On short time scales of >2 hours the source varies smoothly by 15-20%; long-term variations by a factor >2 could not be resolved in the relatively short exposures: we find the source mostly in a ``low'' state, in 2 out of the 11 observations in a ``high state''. X-ray flares seem to be recurrent with a time scale of ∼24ks which, if interpreted as the Keplerian time scale in the disc, would place the emission region just outside the last stable orbit. The X-ray spectrum of PKS 0558-504 can be well fitted by two Comptonization components, one at moderate temperatures of kT∼4.5keV and optical depths of τ∼2, the other at high temperatures (kT>50keV) and low optical depths (τ≲1.0). These parameters are, however, subject to large errors due to the inherent degeneracy of the Comptonization models. Flux variations of the source are caused by changes of the colder component only, the hot component with parameters very similar to those of BLS1 galaxies, stays constant. All results fit nicely the picture that NLS1 galaxies are lower mass objects, accreting close to the Eddington rate emitting X-rays from a very active magnetically powered accretion disc corona.

Abstract Copyright:

Journal keyword(s): galaxies: active - galaxies: ISM - galaxies: nuclei - X-rays: galaxies

Simbad objects: 4

goto Full paper

goto View the references in ADS

Number of rows : 4
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
1 LB 1727 Sy1 04 26 00.7188165240 -57 12 01.769902992 13.68 14.58 14.37 14.8   ~ 271 0
2 QSO B0558-5026 BLL 05 59 47.3916612936 -50 26 52.025952120   15.18 14.97     ~ 283 1
3 Ton 951 Sy1 08 47 42.4485615096 +34 45 04.482515304   14.83 14.50     ~ 463 0
4 Mrk 896 Sy1 20 46 20.8414665240 -02 48 45.360840096   15.27 14.61     ~ 125 0

To bookmark this query, right click on this link: simbad:objects in 2004A&A...415..959B and select 'bookmark this link' or equivalent in the popup menu


© Université de Strasbourg/CNRS

    • Contact