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Deep wide-field H$alpha$+[NII] imaging around the Virgo cluster giant elliptical galaxy M86 reveals a highly complex and disturbed ISM/ICM. The most striking feature is a set of H$alpha$ filaments which clearly connect M86 with the nearby disturbed spiral NGC 4438 (23$$=120 kpc projected away), providing strong evidence for a previously unrecognized collision between them. Spectroscopy of selected regions show a fairly smooth velocity gradient between M86 and NGC 4438, consistent with the collision scenario. Such a collision would impart significant energy into the ISM of M86, probably heating the gas and acting to prevent the gas from cooling to form stars. We propose that cool gas stripped from NGC 4438 during the collision and deposited in its wake is heated by shocks, ram pressure drag, or thermal conduction, producing most of the H$alpha$ filaments. Some H$alpha$ filaments are associated with the well-known ridge of bright X-ray emission to the NW of the nucleus, suggesting that the collision is responsible for peculiarities of M86 previously ascribed to other effects. M86 is radio-quiet, thus AGN heating is unlikely to play a significant role. The M86 system has implications for understanding the role of gravitational interactions in the heating of the ISM in ellipticals, and how collisions in clusters transform galaxies.
Ram pressure stripping of the multiphase ISM is studied in the perturbed Virgo cluster spiral galaxy NGC 4438. This galaxy underwent a tidal interaction ~100 Myr ago and is now strongly affected by ram pressure stripping. Deep VLA radio continuum obs
We present a new deep optical study of a luminosity limited sample of nearby elliptical galaxies, attempting to observe the effects of gravitational interactions on the ISM of these objects. This study is motivated by recent observations of M86, a ne
We present GALEX NUV (2310 A) and FUV (1530 A) images of the interacting galaxy NGC 4438 (Arp 120) in the center of the Virgo cluster. These images show an extended (20 kpc) tidal tail at the north-west edge of the galaxy previously undetected at oth
NGC 1097 is a nearby Seyfert 1 galaxy with a bright circumnuclear starburst ring, a strong large-scale bar and an active nucleus. We present a detailed study of the spatial variation of the far infrared (FIR) [CII]158um and [OI]63um lines and mid-inf
We examined offsets between HII regions and molecular clouds belonging to spiral arms of a late type spiral galaxy NGC 4254 (M99). We used a high resolution CO(1-0) image obtained by Nobeyama Millimeter Array (NMA) and an H-alpha image. We derived an