ar X iv : a st ro - p h / 04 05 43 5 v 1 2 1 M ay 2 00 4 Warm molecular gas in galaxy - galaxy merger NGC 6090

We present observations of the CO 2-1 and 3-2 transitions toward the merging galaxies of NGC6090 with the Submillimeter Array (SMA). The high resolution CO data reveal three gas concentrations. The main component is peaking in the overlap region between the two galaxies, where the near-IR and radio continuum emission are weak. The CO 2-1 emission from the face-on galaxy NGC6090E is somewhat stronger than that from the edge-on galaxy NGC6090W. The CO 3-2 emission peaks in the overlap region, similar to the CO 2-1 emission. More than 50% of the CO 3-2 emission arises from the 2 (1.2 kpc) area of the overlap region. There appears to be CO 3-2 emission toward the nuclear region and the north-west arm of NGC6090E, while no CO 3-2 emission is detected toward NGC6090W. Unlike the CO gas, most of the radio continuum emission comes from NGC6090E. The strong CO emission, together with the weak radio continuum emission, suggests that star formation in the overlap region has not proceeded long enough to produce significant numbers of supernovae which would be detectable due to their radio continuum emission. Subject headings: galaxies: interactions —— galaxies: kinematics and dynamics —– galaxies: individual (NGC6090) Harvard Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138 Astronomy Department, Peking University, Beijing, 100871, China e-mail: [email protected] Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 106, Taiwan The Submillimeter Array (SMA) is a joint project between the Smithsonian Astrophysical Observatory and the Academia Sinica Institute of Astronomy and Astrophysics, and is funded by the Smithsonian Institution and the Academia Sinica.