Bibcode
González-Martín, O.; Vaughan, Simon
Referencia bibliográfica
Half a Century of X-ray Astronomy, Proceedings of the conference held 17-21 September, 2012 in Mykonos Island, Greece. Online at http://www.astro.noa.gr/xcosmo/, id.23
Fecha de publicación:
1
2013
Número de citas
0
Número de citas referidas
0
Descripción
Active galactic nuclei (AGN), powered by accretion onto supermassive
black holes (SMBHs), are thought to be scaled up versions of Galactic
black hole X-ray binaries (BH-XRBs). In the past few years evidence of
such correspondence include similarities in the broadband shape of the
X-ray variability power spectra, with characteristic bend times-cales
scaling with mass. We have characterized the X-ray temporal properties
of a sample of AGN to study the connection among different classes of
AGN and their connection with BH-XRBs. We have performed a uniform
analysis of the power spectrum densities (PSDs) of 104 nearby (z<0.4)
AGN using 209 XMM-Newton/pn observations (Gonzalez-Martin & Vaughan
2012, A&A accepted). Among the entire sample, ~70% show significant
variability in at least one of the three bands tested. A high percentage
of low-luminosity AGN do not show any significant variability (~90% of
LINERs). The PSD of the majority of the variable AGN was well described
by a simple power-law with a mean index of ~2. In 15 sources we found
that the bending power law model was preferred with a mean slope of 2.8
and a mean bend frequency of nu(break) = 2x 10E-04 Hz. Only KUG 1031+398
(RE J1034+396) shows evidence for quasi-periodic oscillations. The
"fundamental plane" relating variability timescale, black hole mass, and
luminosity is studied using the new X-ray timing results presented here
together with a compilation of the previously detected timescales from
the literature. Both quantitative (i.e. scaling with BH mass) and
qualitative (overall PSD shapes) found in this sample of AGN are in
agreement with the expectations for the SMBHs and BH-XRBs being the same
phenomenon scaled-up with the size of the BH. The steep PSD slopes above
the high frequency bend bear a closer resemblance to those of the
"soft/thermal dominated" BH- XRB states than other states.