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M. Das, P.J. Teuben, S.N. Vogel, A. Harris (University of Maryland), M.W. Regan (Space Telescope Science Institute), K. Sheth (California Institute of Technology), T.T. Helfer (University of California at Berkeley), M.D. Thornley (Bucknell University)
Gas inflow in barred galaxies results in mass accumulation in their centers, which can affect the shape of orbits supporting the bar structure. Simulations of bars predict that the bar ellipticity decreases with the mass buildup of the center and can eventually lead to bar dissolution. We have used CO maps from the BIMA Survey of Nearby Galaxies (SONG) (Regan et al 2001) to investigate whether there is observational evidence for this effect. Near-IR images obtained by the SONG team were used to determine the bar axes and ellipticity; the intensity profile was used to determine the bulge diameter. The CO (1-0) emission line observations from SONG were used to derive the rotation curves of these galaxies using a tilted ring model to fit the velocity maps. These rotation curves were used to determine the ratio of the dynamical mass within the bulge to that in the bar as a measure of the central mass concentration. We find an apparent correlation between bar ellipticity and central mass concentration. This is the first observational evidence that bar ellipticity may decrease with nuclear mass; it may indicate that the central mass buildup in bars results ultimately in the dissolution of the bar itself. This work is partially supported by NSF AST 9981289.
The author(s) of this abstract have provided an email address for comments about the abstract: mousumi@astro.umd.edu