Researchers study the active galactic core during its eruption phase

dr Li Shasha and Dr. Feng Haicheng of the Yunnan Observatories of the Chinese Academy of Sciences and her collaborators found evidence of the kinematic evolution of the broadline region of active galactic nuclei.

Their results were published in The Astrophysical Journal on 08/31

Using the 2.4-m telescope at the Lijiang Observatory, researchers conducted a seven-month photometric and spectroscopic monitoring program between 2020 and 2021 to study the geometry and kinematics of the broadline region and measure the mass of the supermassive black hole in changing environments . See active galactic core NGC 4151.

Broad emission lines, prominent features in active galactic cores, are commonly believed to emanate from the broadline region. The gas in the broadline region is very close to the supermassive black hole, so it is important to study the properties of the supermassive black hole and the active galactic core center. However, the details of the kinematics and geometry of the broadline region are not yet well understood.

Reverberation mapping is an effective method to study the broadline region and the supermassive black hole. “We can study the kinematic evolution of a broadline region through multiple reverberation mapping observations,” said Dr. Li

After monitoring NGC 4151 for seven months, researchers obtained the time lags of Hα, Hβ, Hγ, He I, and He II, indicating a layered structure in the broadline region. By combining the velocity width and time lag of each emission line, they also deduced that the mass of the supermassive black hole is about 40 million times the mass of the Sun, consistent with results from other methods.

In addition, the velocity-resolved measurement during the observations revealed a broad region of coexistence of viruses and influxes. Researchers analyzed the historical light curve and compared the observations to previous results. They found that the kinematics of the broadline region have been changing for almost 30 years.

These results on an extremely variable active galactic core suggest that the evolutionary kinematics of a broadline region should be related to the accretion rate of supermassive black holes.