A long XMM-Newton observation of an extreme narrow-line Seyfert 1: PG 1244+026
Abstract
We explore the origin of the strong soft X-ray excess in narrow-line Seyfert 1 galaxies using spectral-timing information from a 120 ks XMM-Newton observation of PG 1244+026. Spectral fitting alone cannot distinguish between a true additional soft X-ray continuum component and strongly relativistically smeared reflection, but both models also require a separate soft blackbody component. This is most likely intrinsic emission from the disc extending into the lowest energy X-ray bandpass. The rms spectra on short time-scales (200-5000 s) contain both (non-disc) soft excess and power-law emission. However, the spectrum of the variability on these time-scales correlated with the 4-10 keV light curve contains only the power law. Together these show that there is fast variability of the soft excess which is independent of the 4-10 keV variability. This is inconsistent with a single reflection component making the soft X-ray excess as this necessarily produces correlated variability in the 4-10 keV bandpass. Instead, the rms and covariance spectra are consistent with an additional cool Comptonization component which does not contribute to the spectrum above 2 keV.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- December 2013
- DOI:
- 10.1093/mnras/stt1801
- arXiv:
- arXiv:1309.5875
- Bibcode:
- 2013MNRAS.436.3173J
- Keywords:
-
- accretion;
- accretion discs;
- galaxies: active;
- galaxies: nuclei;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 15 pages, 12 figures, 5 tables, accepted by MNRAS