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

The existence of intermediate-width emission line regions (IELRs) in activegalactic nuclei has been discussed for over two decades. A consensus, however,is yet to be arrived at due to the lack of convincing evidence for theirdetection. We present a detailed analysis of the broadband spectrophotometry ofthe partially obscured quasar OI 287. The ultraviolet intermediate-widthemission lines (IELs) are very prominent, in high contrast to the correspondingbroad emission lines (BELs) which are heavily suppressed by dust reddening.Assuming that the IELR is virialized, we estimated its distance to the centralblack hole of $\sim 2.9$ pc, similar to the dust sublimation radius of $\sim1.3$ pc. Photo-ionization calculations suggest that the IELR has a hydrogendensity of $\sim 10^{8.8}-10^{9.4} ~ \rm cm^{-3}$, within the range of valuesquoted for the dusty torus near the sublimation radius. Both its inferredlocation and physical conditions suggest that the IELR originates from theinner surface of the dusty torus. In the spectrum of this quasar, we identifiedonly one narrow absorption-line system associated with the dusty material. Withthe aid of photo-ionization model calculations, we found that the obscuringmaterial might originate from an outer region of the dusty torus. We speculatethat the dusty torus, which is exposed to the central ionizing source, mayproduce IELs through photo-ionization processes, while also obscure BELs as anatural "coronagraph". Such a "coronagraph" could be found in a large number ofpartially obscured quasars and be a useful tool to study IELRs.

Detection of the Intermediate-width Emission Line Region in Quasar OI 287 with the Broad Emission Line Region Obscured by the Dusty Torus