2011ApJ...728L..47A

This Letter presents a principal component analysis of rotation curves from a sample of low surface brightness galaxies. The physical meaning of the principal components is investigated and related to the intrinsic properties of the galaxies. The rotation curves are re-scaled using the optical disk scale length, and the resulting principal component decomposition demonstrates that the whole sample is properly approximated using two components. The ratio of the second to the first component is closely related to the inner mass profile, is correlated to the gas fraction in the galaxy, and is uncorrelated to other parameters. As a consequence, the gas fraction appears as a fundamental variable with respect to the galaxies' rotation curves, and its correlation with the inner mass profile is especially important. The effects of noise, re-scaling biases, and systematics are investigated in detail, and the correlation between the principal components' ratio and the gas fraction is demonstrated to be stable. Since the gas fraction is related to the degree of galaxy evolution, it is very likely that the shape of the inner mass profile is a consequence of galaxy evolution. More evolved galaxies have shallower central profiles and statistically less gas, as a consequence of more star formation and supernovae. The differences in evolution, gas fractions, and the inner mass profile of the galaxies could be due to the influence of different environments.