Abstract
The aim of the present study is to contribute to the understanding of physical processes involved in the nuclear region of active galactic nuclei.
NGC 4438 is a peculiar spiral galaxy in the center of the Virgo Cluster [∼16 Mpc], which exhibits the most environmental damage in that cluster. NGC4438 shows evidence of interaction with the intracluster medium (ICM) and with NGC4435.
On the other hand, the nuclear region (classified as a LINER) has an unusual and complex morphology in radio continuum. Images that were taken with HST revealed asymmetric structures (`bubbles') interacting with the ISM. The nucleus lies at the root of these expanding bubbles. The bubbles have a LINER-type spectra, and may be responsible for the LINER qualification in low resolution imaging.
But, which excitation mechanism explains the 10^{53} erg of energy that feeds these bubbles? Does these mechanism correspond to an AGN or to a Starburst? We present ISAAC's observations in the near-infrared (NIR) (JHK & NB filters), that will allow us, along with the spectroscopy, to examine the presence of PAHs in the nucleus, and will help in elucidating the AGN/Starburst dichotomy in LINERS.
