Study provides new insights into broad-line region of active galactic nuclei

Researchers led by Dr. Lu Kaixing from Yunnan Observatories of the Chinese language Academy of Sciences have supplied new insights into the broad-line area (BLR) of the energetic galactic nuclei (AGN), and achieved exact measurements of the supermassive black hole mass in AGN NGC 5548.

The research was revealed in The Astrophysical Journal Complement Collection on Nov. 9.

In 2015, the analysis workforce performed a long-term spectroscopic monitoring venture for a specific pattern of extensively recognized AGNs utilizing the two.4-m telescope of Lijiang observatory. They aimed to analyze the origin and evolution of BLRs, precisely measure the mass of supermassive black holes, and perceive construction and evolution of the AGN.

NGC 5548 with double-peaked broad-line profiles underwent excessive variability previously twenty years, and as a candidate of sub-parsec SMBH binary candidate, was the highest-priority goal of the long-term spectroscopic monitoring marketing campaign.

Reverberation mapping (RM) is a technique to straight detect the scale and constructions of radiation area for the distant AGN in time domain. “Our analysis demonstrates that reverberation mapping is a dependable and efficient methodology to precisely measure the mass of supermassive black hole in AGN,” mentioned Dr. Lu.

At present, this analysis carried out five-season observations for NGC 5548 and obtained five-season measurements of supermassive black hole mass for this AGN, with a dispersion of 13%, which is significantly better than earlier dispersion of 41%.

Taking the 5 seasons of RM measurements into consideration, the seasons of RM measurements for NGC 5548 attain 23 in total, making it essentially the most intensively RM-monitored AGN.

Combining the newest five-season outcomes with historical data, the researchers discovered that the change of the BLR radius lags the various optical luminosity with a timescale of three.5 years, and the road dispersion (i.e., rotation velocity) of the BLR from 23 RM campaigns will not be globally correlated with the optical luminosity.

“Each findings aren’t per the traditional ‘respiration impact’ of the BLR, that’s the BLR radius (measurement) rising and the road width lowering with continuum luminosity,” mentioned Dr. Lu.

The analysis workforce will proceed to watch NGC 5548 to higher perceive the construction and evolution of the BLR.