X-ray variability in a complete sample of soft X-ray selected AGN

被引：89

作者：

Grupe, D

Thomas, HC

Beuermann, K

机构：

[1] Max Planck Inst Extraterr Phys, D-85741 Garching, Germany

[2] Max Planck Inst Astrophys, D-85741 Garching, Germany

[3] Univ Sternwarte, D-37083 Gottingen, Germany

来源：

ASTRONOMY & ASTROPHYSICS | 2001年 / 367卷 / 02期

关键词：

accretion; accretion disks; galaxies : active; galaxies : nuclei of; galaxies : Seyfert; quasars : general;

D O I：

10.1051/0004-6361:20000429

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We present ROSAT All-Sky Survey and ROSAT pointed observations (PSPC and HRI) of a complete sample of 113 bright soft X-ray AGN selected from the ROSAT Bright Source Catalog. We compare these observations in order to search for extreme cases of flux and spectral X-ray variability - X-ray transient AGN. Three definite transients and one transient candidate are found. The other sources show amplitude variations typically by factors of 2-3 on timescales of years. We found that the variability strength on timescales of days is a function of the steepness of the X-ray spectrum: steeper X-ray objects show stronger variability than flat X-ray spectrum sources. We also present new HRI measurements of our extreme X-ray transients IC 3599 and WPVS007. We discuss possible models to explain the X-ray transience and the variabilities observed in the non-transient sources.

引用

页码：470 / 486

页数：17

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