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

Changing-look active galactic nuclei (AGNs) present an important laboratoryto understand the origin and physical properties of the broad-line region(BLR). We investigate follow-up optical spectroscopy spanning $\sim 500$ daysafter the outburst of the changing-look AGN 1ES\,1927+654. The emission linesdisplayed dramatic, systematic variations in intensity, velocity width,velocity shift, and symmetry. Analysis of optical spectra and multi-band imagesindicate that the host galaxy contains a pseudobulge and a total stellar massof $3.56_{-0.35}^{+0.38} \times 10^{9}\, M_\odot$. Enhanced continuum radiationfrom the outburst produced an accretion disk wind, which condensed into BLRclouds in the region above and below the temporary eccentric disk. Broad Balmerlines emerged $\sim 100$ days after the outburst, together with an unexpected,additional component of narrow-line emission. The newly formed BLR clouds thentraveled along a similar eccentric orbit ($e \approx 0.6$). The Balmerdecrement of the BLR increased by a factor of $\sim 4-5$ as a result of secularchanges in cloud density. The drop in density at late times allowed theproduction of \hei\ and \heii\ emission. The mass of the black hole cannot bederived from the broad emission lines because the BLR is not virialized.Instead, we use the stellar properties of the host galaxy to estimate$M_\mathrm{BH} = 1.38_{-0.66}^{+1.25} \times 10^{6}\, M_\odot$. The nucleusreached near or above its Eddington limit during the peak of the outburst. Wediscuss the nature of the changing-look AGN 1ES\,1927+654 in the context ofother tidal disruption events.

The Host Galaxy and Rapidly Evolving Broad-line Region in the Changing-look Active Galactic Nucleus 1ES 1927+654