For refcode 2012A&A...542A..83P: Retrieve 168 NED objects in this reference. Please click here for ADS abstract
NED Abstract
Copyright by European Southern Observatory (ESO).
Reproduced by permission
2012A&A...542A..83P
CAIXA: a catalogue of AGN in the XMMNewton archive. III. Excess variance
analysis<xref reftype="fn" rid="FN1 <xref reftype="fn" rid="FN2 *
Ponti, G.; Papadakis, I.; Bianchi, S.; Guainazzi, M.; Matt, G.; Uttley,
P.; Bonilla, N. F.
Abstract. Context. We report on the results of the first XMMNewton
systematic "excess variance" study of all the radio quiet, Xray
unobscured AGN. The entire sample consist of 161 sources observed by
XMMNewton for more than 10 ks in pointed observations, which is the
largest sample used so far to study AGN Xray variability on time scales
less than a day.
Aims: Recently it has been suggested that the same engine might be at
work in the core of every black hole (BH) accreting object. In this
hypothesis, the same variability should be observed in all AGN, once
rescaled by the M_BH_ (M_BH_) and accretion rate (m).
Methods: We systematically compute the excess variance for all AGN, on
different timescales (10, 20, 40 and 80 ks) and in different energy bands
(0.30.7, 0.72 and 210 keV).
Results: We observe a highly significant and tight (~0.7 dex) correlation
between sigma^2^_rms_ and M_BH_. The subsample of reverberation mapped AGN
shows an even smaller scatter (only a factor of 23) comparable to the one
induced by the M_BH_ uncertainties. This implies that Xray variability
can be used as an accurate tool to measure M_BH_ and this method is more
accurate than the ones based on single epoch optical spectra. This allows
us to measure M_BH_ for 65 AGN and estimate lower limits for the remaining
96 AGN. On the other hand, the sigma^2^_rms_ vs. accretion rate dependence
is weaker than expected based on the PSD break frequency scaling. This
strongly suggests that both the PSD high frequency break and the
normalisation depend on accretion rate in such a way that they almost
completely counterbalance each other (PSD_amp_ is proportional to
m^0.8^). A highly significant correlation between sigma^2^_rms_ and 210
keV spectral index is observed. The highly significant correlations
between sigma^2^_rms_ and both the L_Bol_ and the FWHM_Hbeta_ are
consistent with being just byproducts of the sigma^2^_rms_ vs. M_BH_
relation. The soft and medium sigma^2^_rms_ is very well correlated with
the hard sigma^2^_rms_, with no deviations from a linear one to one
correlation. This suggests that the additional soft components (i.e. soft
excess, warm absorber) add a minor contribution to the total variability.
Once the variability is rescaled for M_BH_ and m, no significant
difference between narrowline and broadline Seyfert 1 is observed.
Conclusions: The results are in agreement with a picture where, to first
approximation, all local AGN have the same variability properties once
rescaled for M_BH_ and m.
Appendix A is available in electronic form at http://www.aanda.orgFull
Tables 1 and 2 are only available at the CDS via anonymous ftp to
cdsarc.ustrasbg.fr (130.79.128.5) or via
http://cdsarc.ustrasbg.fr/vizbin/qcat?J/A+A/542/A83
Key words: accretion, accretion disks, black hole physics, methods: data
analysis, galaxies: active, galaxies: nuclei, Xrays: galaxies
Retrieve 168 NED objects in this reference. Please click here for ADS abstract
