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Session 21 - Luminous Infrared Galaxies.
Display session, Wednesday, January 07
Intense bursts of star formation are observed to occur as a result of a collision or a merger in many gas-rich galaxies. This star formation can take place in the nuclear region and in far-flung tidal features, such as tidal tails, as well as in the disk of the galaxy in dense structures produced by the collision. Thus the induced star formation takes place in a variety of global environments. Large flows of gas and stars result from these collisions and the details of the star formation histories are correlated with the extreme density increases and strong shocks that result in the gas. The optically identified collisionally produced 'ring-galaxies' are very good systems for study of the induced star formation because in these it occurs in an expanding ring or arc of high density gas. This relatively simple morphology allows for direct comparison between models and observed quantities. Here we display the results of a comparison between our numerical (3D, N-body/SPH) simulations of collisionally produced ri ng galaxy systems and multiwavelength data for the ring galaxy system Arp 118. Our best-fit simulation is of an off-center collision between an elliptical and a gas-rich disk galaxy in which the mass ratio is 1:4. Using this we obtain valuable information on the timescales for different phases of the star formation as well as the global dynamics of the collision. The results may be applicable to the interpretation of the bright star-forming arcs and rings observed in high-redshift clusters of galaxies.
Program listing for Wednesday