2023MNRAS.520.6190Z

In this paper, an interesting method is proposed to test dual-core systems for double-peaked narrow emission lines through a precious dual-core system with double-peaked narrow Balmer lines in the main galaxy but with single-peaked narrow Balmer lines in the companion galaxy. Under a dual-core system, considering narrow Balmer (Hα and Hβ) emissions (f_e,α and f_e,β) from a companion galaxy that are covered by the SDSS fiber for the main galaxy and narrow Balmer emissions (f_c,α and f_c,β) from the companion galaxy covered by the SDSS fiber for the companion galaxy, the same flux ratios f_e,α/f_c,α = f_e,β/f_c,β can be expected, owing to the totally similar physical conditions of each narrow Balmer emission region. Next, the precious dual-core system in SDSS J2219-0938 is discussed. After subtracting the PPXF code determined stellar lights, double-peaked narrow Balmer emission lines are confirmed in the main galaxy with a confidence level higher than 5σ, but single-peaked narrow Balmer emission lines are confirmed in the companion galaxy. Through measured fluxes of the emission components, f_e,α/f_c,α is about 0.82, which is different from f_e,β/f_c,β ∼ 0.52, which disfavours a dual-core system for the double-peaked narrow Balmer emission lines in SDSS J2219-0938.