Searching double-peaked emission-line profiles in the spectra of galaxies through the symmetry of the cross-correlation function

The presence of double-peaked/multi-component emission-line profiles in the spectra of galaxies is commonly identified by visual inspection. However, the identification of complex emission-line profiles by eye is unlikely for large data bases such as the Sloan Digital Sky Survey (SDSS) or the integral field spectroscopy surveys of galaxies (e.g. Calar Alto Legacy Integral Field Area Survey or The Mapping Nearby Galaxies at APO). We describe a quick method involving a cross-correlation technique for detecting the presence of complex (double-peaked or multiple components) profiles in the spectra of galaxies, deriving simultaneously a first estimation of the velocity dispersions and radial velocities of the dominant gaseous component. We illustrate the proposed procedure with the well-known complex [O III]lambda lambda 4959, 5007 profiles of the central region of NGC 1068.