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

The physical origins of components in the unified model of quasars such asbroad line region (BLR), dust torus, and narrow line region are unresolved. Tolearn more about them, we focus on studying Changing-State Quasars (also knownas Changing-Look Quasars) as they offer the opportunity to observe structuralchanges associated with state transitions. This can give us insight into theorigins of each quasar structure. We aimed to understand the central corestructure of one of the most variable Changing-State Quasars, SDSSJ125809.31+351943.0, and how it changes before and after the state transition.We performed reverberation mapping with optical spectroscopy to investigate thestructure of the BLR and to measure the black hole mass. The results of thereverberation mapping show that the Eddington ratio crossed the value of 0.01before and after state transition for the black hole mass of$10^{9.46^{+0.15}_{-0.19}}\rm{M_\odot}$. In addition, we compared optical toX-ray spectral indices ($\alpha_{\rm{ox}}$) before and after the statetransition to investigate the structure difference of the accretion disk. Thesevariations in $\alpha_{\rm{ox}}$ and the Eddington ratio were found to behavesimilarly to the state transition seen in X-ray binary systems. We alsomeasured the time-lag between the mid-IR and the optical light curve toestimate the size of the dust torus. From all the acquired information aboutthe BLR and dust torus, we confirmed the existence of two distinctrotating/inflowing BLR components located near the dust torus, probablygenerated by different processes, which are the origins of the BLRs.

Probing the origin of the two-component structure of broad line region by reverberation mapping of an extremely variable quasar