出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：The X-ray transient AGN WPVS 007 was an X-ray bright source during the ROSAT All-Sky Survey, but then basically disappeared from the X-ray sky for almost two decades. FUSE observations in 2003 revealed the nature of this disappearance: strong absorption. FUSE spectra showed deep absorption line troughs in the UV spectrum of WPVS 007. These findings make this AGN a direct link between NLS1s and Broad Absorption Line QSOs which are both thought to be high L/Ledd AGN. In recent years Swift was able to detect WPVS 007 in X-rays at relatively bright states several times, suggesting that the absorber may have started to disappear or become more leaky. In some ways similar is the NLS1 Mkn 335 which has been observed in X-rays in a bright state over decades, but was found by Swift in an extremely low state in May 2007. Our XMM observation of Mkn 335 from June 2009 is well fit by the presence of a strong ionized partial covering absorber.
