Early-type galaxies in the near-infrared: 1.5–2.4

Context. Near-infrared (hereafter NIR) data may provide complementary information to the traditional optical population synthesis analysis of unresolved stellar populations because the spectral energy distribution of the galaxies in the 1–2.5 μm range is dominated by different types of stars than at optical wavelengths. Furthermore, NIR data are less affected by dust absorption and hence could constrain the stellar populations in dust-obscured galaxies. Aims. We attempt to develop observational constraints on the stellar populations of unresolved stellar systems in the NIR. Methods. To achieve this goal, we require benchmark NIR spectra of “simple” early-type galaxies, to test and calibrate the outputs of population synthesis models. We obtained low-resolution (R ~ 1000) long-slit spectra between 1.5 and 2.4 μm for 14 nearby early-type galaxies using SofI at the ESO 3.5-m New Technology Telescope and higher resolution (R ~ 3000) long-slit spectra, centered on Mg