We report on a detailed study of the stellar populations and ionized gas properties in the merger LIRG NGC 2623 , analysing optical Integral Field Spectroscopy from the CALIFA survey and PMAS LArr , multiwavelength HST imaging , and OSIRIS narrow band H \alpha and [ NII ] \lambda 6584 imaging .
The spectra were processed with the starlight full spectral fitting code , and the results compared with those for two early-stage merger LIRGs ( IC 1623 W and NGC 6090 ) , together with CALIFA Sbc/Sc galaxies .
We find that NGC 2623 went through two periods of increased star formation ( SF ) , a first and widespread episode , traced by intermediate-age stellar populations ISP ( 140 Myr–1.4 Gyr ) , and a second one , traced by young stellar populations YSP ( < 140 Myr ) , which is concentrated in the central regions ( < 1.4 kpc ) .
Our results are in agreement with the epochs of the first peri-center passage ( \sim 200 Myr ago ) and coalescence ( < 100 Myr ago ) predicted by dynamical models , and with high resolution merger simulations in the literature , consistent with NGC 2623 representing an evolved version of the early-stage mergers .
Most ionized gas is concentrated within < 2.8 kpc , where LINER-like ionization and high velocity dispersion ( \sim 220 km/s ) are found , consistent with the previously reported outflow .
As revealed by the highest resolution OSIRIS and HST data , a collection of HII regions is also present in the plane of the galaxy , which explains the mixture of ionization mechanisms in this system .
It is unlikely that the outflow in NGC 2623 will escape from the galaxy , given the low SFR intensity ( \sim 0.5 M _ { \odot } yr ^ { -1 } kpc ^ { -2 } ) , the fact that the outflow rate is 3 times lower than the current SFR , and the escape velocity in the central areas higher than the outflow velocity .