Effects of Galaxy Interaction on the TullyFisher Relation CO vs HI Linewidths.pdf

AA manuscript no. (will be inserted by hand later) ASTRONOMY AND Your thesaurus codes are: ASTROPHYSICS 03 (12.04.3; 11.04.1; 11.09.2; 11.07.1; 11.09.4; 13.19.1) 5.2.2008 Effects of Galaxy Interaction on the Tully-Fisher Relation: CO vs HI Linewidths Y. Tutui and Y. Sofue Institute of Astronomy, University of Tokyo, Mitaka, Tokyo 181, Japan; E-mail: tutui@mtk.ioa.s.u-tokyo.ac.jp 7 received July 1, 1996 / accepted June 9, 1997 9 9 1 Abstract. We investigate effects of galaxy-galaxy inter- 45-m telescope (HPBW = 15”), and CO linewidths have n action on the Tully-Fisher relation. The HI linewidth in been obtained for galaxies at redshift cz ∼ 29,000 km s−1 u interacting galaxies is significantly broader than the CO (Sofue et al. 1996), at which the CO beamsize is still small J linewidth, and the HI to CO linewidth ratio is propor- enough to distinguish galaxies. 8 tional to the strength of interaction. This provides dif- HI gas extends far from the center of galaxies beyond 2 ferent distances to galaxies measured by the Tully-Fisher the optical radius, while it is deficient in the central re- relation with the CO and HI linewidths. Distances derived gion (Bosma 1981). On the other hand, the molecular 2 v from the HI linewidths are 62% larger than those derived gas is known to be more concentrated in a better cor- 0 from the CO linewidths for strongly interacting galaxies, relati