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

NGC 5548 is one of the active galactic nuclei (AGN) selected for ourlong-term spectroscopic monitoring with the Lijiang 2.4~m telescope, aiming atinvestigating the origin and evolution of the broad-line regions (BLRs),accurately measuring the mass of the supermassive black holes (SMBHs), andunderstanding structure and evolution of the AGN. We have performed five-seasonobservations for NGC~5548 with the median sampling interval ranging from 1.25to 3 days. The light curves of the 5100~\AA\ continuum and broad emission linesare measured after subtracting contamination of the host galaxy starlight. Thetime lags of the broad He~{\sc ii}, He~{\sc i}, H$\gamma$, and H$\beta$ lineswith respect to the 5100~\AA\ continuum are obtained for each season and theirmean time lags over the five seasons are 0.69, 4.66, 4.60, 8.43 days,respectively. The H$\gamma$ and H$\beta$ velocity-resolved lag profiles in theseasons of 2015, 2018, 2019, and 2021 are constructed, from which an``M-shaped'' structure is found in 2015 but disappears after 2018. Ourfive-season reverberation mapping (RM) yields an averaged virial SMBH mass of$M_\bullet/10^7M_\odot=14.22$, with a small standard deviation of $1.89$. Bycombining the previous 18 RM campaigns and our five-season campaign forNGC~5548, we find that there exists a time lag of 3.5~years between the changesin the BLR size and optical luminosity. In addition, we also construct the BLRradius$-$luminosity relation and the virial relation for NGC~5548.

Supermassive Black Hole and Broad-line Region in NGC~5548: Results from Five-season Reverberation Mapping