ARK 564: A ''VERY HIGH STATE

Recent RXTE and XMM observations have revealed characteristic time scales inthe power spectra of AGN. The AGN PSDs appear to be similar to the power spectraof Galactic Xray binaries, except from Ark 564. There are two breakfrequencies in the power spectrum of this source, but none of them appears toscale linearly with central black hole mass when compared with the appropriatebreak frequencies found in the PSDs of Galactic sources at low/hard orhigh/soft state. Here we propose a long (95 ksec) XMM observation of Ark 564in order to detrmine accurately its high frequency PSD and investigate whetherthis source is unique among AGN with known PSDs, or its variability propertiesare similar to the properties of Galactic Xray sources at the very high state. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]