Double-peaked Narrow Emission-line Galaxies in SDSS-IV MaNGA

Abstract

Narrow emission lines in a galaxy’s spectrum that show double peaks indicate the presence of distinct gas components with different velocities, and its physical origin remains uncertain. This study uses galaxies from the final MaNGA data release to detect double-peaked narrow emission-line spaxels (DPSs) by examining the double Gaussian profiles of the Hα-[N ii] doublets across all MaNGA spaxels. A total of 5420 DPSs associated with 304 double-peaked narrow emission-line galaxies (DPGs) are identified, with each DPG containing a minimum of five DPSs and being free from overlap with other galaxies. We find that DPSs can be categorized into three groups according to their central distance r/R e and the velocity difference Δv between their two components: the inner low-Δv, inner high-Δv, and outer DPSs. By incorporating the physical characteristics of the DPGs into their DPSs, we demonstrate for the first time the existence of statistical correlations between barred DPGs and inner low-Δv DPSs, AGN-hosting DPGs, and inner high-Δv DPSs, as well as tidal DPGs and outer DPSs.