Researchers led by Qian Yang from Peking University found 21 active galactic nuclei (AGN) of a rare type - AGN with a variable view. This doubles the total number of similar objects found.
AGN is a compact area in the galactic center that is lighter than the surrounding light of a galaxy. They are extremely energetic due to the presence of a black hole or an active stellar birth. Usually AGN is divided into two groups, based on the characteristic of emission lines.
AGN-1 show wide and narrow emission lines, and AGN-2 - only narrow. But a review shows that some AGNs go between different spectral types. The list contained less than 20 such objects, referred to as AGN with a variable view (CL).
Light curves (left) and spectra (right) of the new CL AGN J0831 + 3646 However, the new review showed 21 new objects at once. The detection was made possible by analyzing sets of complex spectroscopic and photometric data from the Sloan Digital Sky Survey (SDSS) and the observation of the Chinese Large-scale Multipurpose Fiber Optic Telescope (LAMOST).
Five of the 21 new CL AGNs found repeated spectra (SDSS). Ten were noted on the basis of repeated spectra from SDSS and LAMOST, and the rest were selected based on photometric variability in the data of optical and average IR imaging.
Approximately 8 new objects passed between classes 1 and 2, 11 between 1 and 1.9, and the rest between 1 and 1.8. Now researchers plan to study in more detail the found CL AGN in order to track the probable mechanism of transition.
