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

We investigate the spectral properties of an active black hole, member of a massive ( 10 7 –10 9  M ⊙  ) sub‐parsec black hole binary. We work under the hypothesis that the binary, surrounded by a circumbinary disc, has cleared a gap, and that accretion occurs on to the secondary black hole fed by material closer to the inner edge of the disc. Broad line emission clouds orbit around the active black hole and suffer erosion due to tidal truncation at the Roche Lobe surface, following gap opening and orbital decay. We consider three of the most prominent broad emission lines observed in the spectra of active galactic nuclei (AGNs), i.e. C  iv , Mg  ii  and  Hβ , and compute the flux ratios between the lines of Mg  ii  and C  iv  () and those of Mg  ii  and  Hβ  (). We find that close black hole binaries have  up to 1 order of magnitude smaller than single black holes. By contrast  may be significantly reduced only at the shortest separations. Peculiarly low values of line flux ratios together with large velocity offsets between the broad and narrow emission lines and/or periodic variability in the continuum (on time‐scales  ≳  years) would identify genuine sub‐pc binary candidates.

Search for sub‐parsec massive binary black holes through line diagnosis