English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We report on the results of the first XMM systematic "excess variance" studyof all the radio quiet, X-ray un-obscured AGN. The entire sample consist of 161sources observed by XMM for more than 10 ks in pointed observations which isthe largest sample used so far to study AGN X-ray variability on time scalesless than a day. We compute the excess variance for all AGN, on differenttime-scales (10, 20, 40 and 80 ks) and in different energy bands (0.3-0.7,0.7-2 and 2-10 keV). We observe a highly significant and tight (~0.7 dex)correlation between excess variance and MBH. The subsample of reverberationmapped AGN shows an even smaller scatter (~0.45 dex) comparable to the oneinduced by the MBH uncertainties. This implies that X-ray variability can beused as an accurate tool to measure MBH and this method is more accurate thanthe ones based on single epoch optical spectra. The excess variance vs.accretion rate dependence is weaker than expected based on the PSD breakfrequency scaling, suggesting that both the PSD high frequency break and thenormalisation depend on accretion rate in such a way that they almostcompletely counterbalance each other. A highly significant correlation betweenexcess variance and 2-10 keV spectral index is observed. Both the variabilityvs. LBol and FWHM_Hbeta correlations are consistent with being just by-productsof the correlation with MBH. The soft and medium variability is very wellcorrelated with the hard variability, suggesting that the additional softcomponents (i.e. soft excess, warm absorber) add a minor contribution to thetotal variability. Once the variability is rescaled for MBH and mdot, nosignificant difference between narrow-line and broad-line Seyfert 1 isobserved. The results are in agreement with a picture where, to firstapproximation, all local AGN have the same variability properties once rescaledfor MBH and accretion rate.

CAIXA: a catalogue of AGN in the XMM-Newton archive III. Excess Variance Analysis