1.65-μm (H-band) surface photometry of galaxies - VIII. The near-IRκspace atz=0

Abstract

We present the distribution of a statistical sample of nearby galaxies in the κ-space (κ1∝log M, κ2∝log Ie3M/L, κ3∝log M/L). Our study is based on near-IR (H-band: λ=1.65 μm) observations, for the first time comprising early- and late-type systems. Our data confirm that the mean effective dynamical mass-to-light ratio M/L of the E+S0+S0a galaxies increases with increasing effective dynamical mass M, as expected from the existence of the Fundamental Plane relation. Conversely, spiral and Im/BCD galaxies show a broad distribution in M/L with no detected trend of M/L with M, the former galaxies having M/L values about twice larger than the latter, on average. For all the late-type galaxies, the M/L increases with decreasing effective surface intensity Ie, consistent with the existence of the Tully–Fisher relation. These results are discussed on the basis of the assumptions behind the construction of the κ-space and their limitations. Our study is complementary to a previous investigation in the optical (B-band: λ=0.44 μm) and allows us to study wavelength dependences of the galaxy distribution in the κ-space. As a first result, we find that the galaxy distribution in the κ1–κ2 plane reproduces the transition from bulgeless to bulge-dominated systems in galaxies of increasing dynamical mass. Conversely, it appears that the M/L of late-types is higher (lower) than that of early-types with the same M in the near-IR (optical). The origins of this behaviour are discussed in terms of dust attenuation and star formation history.