The peculiar galaxy Mkn 298 revisited with integral field spectroscopy

Spectroscopic and imaging data of the peculiar galaxy Mkn 298 are presented. Narrow-band Hα and broad-band R images are used to study the star formation rate in the galaxy and its morphology, which is typical of a merging system. Long-slit and integral field spectra are used to assess the kinematics of gas and stars, and the nature of the ionizing source at dif- ferent distances from the nucleus. In particular, the nucleus of Mkn 298 is characterized by peculiar line ratios: (N )λ6583/Hα is typical of H -like regions, while (O )λ6300/Hα could indicate the presence of an active galactic nucleus. We show that models where a shock component is added to photoionization from a starburst allow us to reproduce the observed line ratios. Mkn 298 is thus most likely a star-forming galaxy, rather than a galaxy hosting an active nucleus.