ROSAT monitoring of persistent giant and rapid variability in the narrow-line Seyfert 1 galaxy IRAS 13224-3809

Autor:	W. N. Brandt, Th. Boiler, H. H. Fink, A. C. Fabian
Rok vydání:	1997
Předmět:	Physics Astrophysics (astro-ph) FOS: Physical sciences High resolution Astronomy Astronomy and Astrophysics Astrophysics Galaxy Amplitude Accretion disc Space and Planetary Science ROSAT Relativistic quantum chemistry
Zdroj:	Monthly Notices of the Royal Astronomical Society. 289:393-405
ISSN:	1365-2966 0035-8711
DOI:	10.1093/mnras/289.2.393
Popis:	We report evidence for persistent giant and rapid X-ray variability in the radio-quiet, ultrasoft, strong Fe II, narrow-line Seyfert 1 galaxy IRAS 13224-3809. Within a 30 day ROSAT High Resolution Imager (HRI) monitoring observation at least five giant amplitude count rate variations are visible, with the maximum observed amplitude of variability being about a factor of 60. We detect a rise by a factor of about 57 in just two days. IRAS 13224-3809 appears to be the most X-ray variable Seyfert known, and its variability is probably nonlinear. We carefully check the identification of the highly variable X-ray source with the distant galaxy, and it appears to be secure. We examine possible explanations for the giant variability. Unusually strong relativistic effects and partial covering by occulting structures on an accretion disc can provide plausible explanations of the X-ray data, and we explore these two scenarios. Relativistic boosting effects may be relevant to understanding the strong X-ray variability of some steep spectrum Seyferts more generally. Comment: 14 pages, submitted to MNRAS
Databáze:	OpenAIRE
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