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We use X-ray monitoring data obtained over a broad range of time-scales to measure the broadband power spectral density functions (PSDs) of two Seyfert galaxies, the broad line Seyfert 1 NGC 3227 and the Seyfert 2 NGC 5506, which has recently been identified as an obscured Narrow Line Seyfert 1 (NLS 1). Using a Monte-Carlo fitting technique we demonstrate that both PSDs are reminiscent of the PSD of black hole X-ray binaries (BHXRBs) in the high/soft state, and specifically rule out a low/hard state PSD shape in NGC 3227. This result demonstrates that, at least where variability is concerned, broad line Seyferts with hard X-ray spectra (photon index~1.6) are not simply the analogues of the low/hard state in BHXRBs, and the dichotomy of NLS 1 and broad line Seyferts cannot be simply interpreted in terms of the two states. We show that the PSD normalisation in NGC 3227 is strongly energy dependent, with larger variability amplitudes at lower energies, unlike NGC 5506 which shows little energy-dependence of variability. We demonstrate that this difference is caused by spectral pivoting of the continuum in NGC 3227 at high energies, which is probably also related to the large amplitude of variability seen in the 2-10 keV band in this AGN. Using the new PSD data and new results in the literature, we replot the PSD break time-scale versus mass plot for all AGN with PSD breaks measured so far, and demonstrate that higher accretion-rate AGN appear to have relatively shorter break time-scales for their black hole mass than lower-accretion rate AGN.
We present a series of X-ray variability results from a long XMM-Newton + NuSTAR campaign on the bright, variable AGN NGC 3227. We present an analysis of the lightcurves, showing that the source displays typically softer-when-brighter behaviour, alth
We present a detailed analysis of broad band X-ray data of the Seyfert 2 galaxy NGC5506. 2-10 keV band are detected during a 1-day ASCA observation, while no significant change in the 2-10 keV continuum shape is found. The ASCA spectrum consists of a
NuSTAR observed the bright Compton-thin, narrow line Seyfert 1 galaxy, NGC 5506, for about 56 ks. In agreement with past observations, the spectrum is well fit by a power law with Gamma~1.9, a distant reflection component and narrow ionized iron line
We present results of a 100 ks XMM observation of the Seyfert 1.5 NGC 3227. Our best-fit broadband model to the pn spectrum consists of a moderately flat (photon index 1.57) hard X-ray power-law absorbed by cold gas with N_H = 3 * 10^21 cm^-2, plus a
We present a flux-resolved X-ray analysis of the dwarf Seyfert 1.8 galaxy NGC 4395, based on three archival $XMM-Newton$ and one archival $NuSTAR$ observations. The source is known to harbor a low mass black hole ($sim 10^4- {rm a~ few~}times 10^{5}~