Exceptional AGN long-timescale X-ray variability: The case of PHL 1092

• Main Authors: Gallo L.C., Fabian A.C., Schneider D.P., Brandt W.N., Miniutti G., Boller Th.
• Format: Article
• Language: English
• Published: EDP Sciences 2012-12-01
• Series: EPJ Web of Conferences
• Online Access: http://dx.doi.org/10.1051/epjconf/20123906002

PHL 1092 is a z ∼ 0.4 high-luminosity counterpart of the class of Narrow–Line Seyfert 1 galaxies. In 2008, PHL 1092 was found to be in a remarkably low X-ray flux state during an XMM–Newton observation. Its 2 keV flux density had dropped by a factor of ∼ 260 with respect to a previous observation performed 4.5 yr earlier. The UV flux remained almost constant, resulting in a significant steepening of the optical-to-X-ray slope αox from − 1.57 to − 2.51, making PHL 1092 one of the most extreme X-ray weak quasars with no observed broad absorption lines (BALs) in the UV. We have monitored the source since 2008 with three further XMM–Newton observations, producing a simultaneous UV and X-ray database spanning almost 10 yr in total in the activity of the source. We present here results from our monitoring campaign.