The origin of double-peak emission-line galaxies: Rotating discs, bars, or galaxy mergers?

Emission lines with a double-peak (DP) shape, detected in the centre of galaxies, have been extensively used past to identify peculiar kinematics such as dual active galactic nuclei (AGNs), outflows, or mergers. With more general approach considering large DP galaxy sample selected from Sloan Digital Sky Survey (SDSS), connection minor merger galaxies ongoing star formation was suggested. To gain better understanding different mechanisms creating signature, this paper, we explore synthetic SDSS spectroscopic observations computed disc models and simulations. We show how signature is connected central part rotation curve which mostly shaped by stellar bulge. We, furthermore, find that bars can create strong emission-line signatures when viewed along their major axis. Major mergers form rotating late post-coalescence stages (1 Gyr after final coalescence), creates signature. Minor tend feature no correlation inclination within 350 Myr coalescence. Comparisons these scenarii disfavour mergers, since they predominantly elliptical only few S0 morphologies. Furthermore, at stage, enhanced most likely faded. Bars on other hand, be compared quite well observations. Both coincide increased found observations, particular do not any dependency observation direction. However, resolving spatially are needed distinguish between discussed possibilities. More insight into origin will gained broader comparison cosmological The provide important tools study mass growth future high redshift surveys.