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 Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Recent studies of active galactic nuclei (AGNs) found a statistically inverse linear scaling between the X-ray normalized excess variance sigma(2)(rms) (variability amplitude) and the black hole (BH) mass spanning over M-BH = 10(6)-10(9) M-circle dot. Suggested as having a small scatter, this scaling relation may provide a novel method to estimate the BH mass of AGNs. However, a question arises as to whether this relation can be extended to the low-mass regime below similar to 10(6) M-circle dot. If confirmed, it would provide an efficient tool to search for AGNs with low-mass BHs using X-ray variability. This paper presents a study of the X-ray excess variances for a sample of AGNs with BH masses in the range of 10(5)-10(6)M(circle dot) observed with XMM-Newton and ROSAT, including data both from the archives and from newly preformed observations. It is found that the relation is no longer a simple extrapolation of the linear scaling; instead, the relation starts to flatten at similar to 10(6) M-circle dot toward lower masses. Our result is consistent with the recent finding of Ludlam et al. Such a flattening of the M-BH-sigma(2)(rms) relation is actually expected from the shape of the power spectrum density of AGNs, for which the break frequency is inversely scaled with the mass of BHs.

ON THE BLACK HOLE MASS—X-RAY EXCESS VARIANCE SCALING RELATION FOR ACTIVE GALACTIC NUCLEI IN THE LOW-MASS REGIME