The orbital kinematics of kpc-scale dual-core systems with double-peaked narrow emission lines

ABSTRACT In this work, based on Sloan Digital Sky Survey (SDSS) photometry and spectroscopy, a method is proposed to test the hypothesis that the orbital kinematics of kpc-scale dual-core systems can lead to double-peaked narrow emission lines (DPNELs), through analysing a sample of seven kpc-scale dual-core systems by comparing the upper limits of their orbital velocities (calculated using total stellar mass and projected distance) with the velocity separation of DPNELs (peak separation). To determine accurate total stellar masses, GALFIT is applied to consider the effects of overlapping components on the photometric images to obtain accurate magnitudes. Then, based on the correlation between absolute Petrosian magnitudes and total stellar masses, the individual masses of the galaxies are determined. Therefore, the maximum orbital velocities can be calculated by combining the projected distance. Meanwhile, the peak separation can be measured accurately after subtracting the penalized pixel-fitting (pPXF) determined host galaxy contributions. Finally, four objects exhibit peak separations almost consistent with their respective maximum orbital velocities under the assumption of a circular orbit, while the remaining three objects display peak separations larger than the maximum orbital velocities. A larger sample will be used later to test further whether DPNELs can arise from kpc-scale dual-core systems.