We observed 12 nearby H I-detected early-type galaxies (ETGs) of stellar mass ∼1010 M⊙ ≤ M* ≤ ∼1011 M⊙ with the Mitchell Integral-Field Spectrograph, reaching approximately three half-light radii in most cases. We extracted line-of-sight velocity distributions for the stellar and gaseous components. We find little evidence of transitions in the stellar kinematics of the galaxies in our sample beyond the central effective radius, with centrally fast-rotating galaxies remaining fast-rotating and centrally slow-rotating galaxies likewise remaining slow-rotating. This is consistent with these galaxies having not experienced late dry major mergers; however, several of our objects have ionized gas that is misaligned with respect to their stars, suggesting some kind of past interaction. We extract Lick index measurements of the commonly used H β, Fe5015, Mg b, Fe5270 and Fe5335 absorption features, and we find most galaxies to have flat H β gradients and negative Mg b gradients. We measure gradients of age, metallicity and abundance ratio for our galaxies using spectral fitting, and for the majority of our galaxies find negative age and metallicity gradients. We also find the stellar mass-to-light ratios to decrease with radius for most of the galaxies in our sample. Our results are consistent with a view in which intermediate-mass ETGs experience mostly quiet evolutionary histories, but in which many have experienced some kind of gaseous interaction in recent times.
Bibliographical noteCopyright 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. First published in Monthly Notices of the Royal Astronomical Society, 471(4), pp.4005–4026. The original publication is available at https://doi.org/10.1093/mnras/stx1835. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.
- ISM: kinematics and dynamics
- galaxies: elliptical and lenticular, cD
- galaxies: evolution
- galaxies: ISM
- galaxies: kinematics and dynamics
- galaxies: structure