We present new radially resolved spectroscopy of 8 early-type galaxies in the Abell 262 cluster. The measurements include stellar rotation, velocity dispersion, H 3 and H 4 coefficients of the lineof-sight velocity distribution along the major and minor axes and an intermediate axis as well as line-strength index profiles of Mg, Fe and Hβ. The ionized-gas velocity and velocity dispersion is measured for 6 sample galaxies along different axes. We derive dynamical mass-to-light ratios and dark matter densities from orbit-based dynamical models, complemented by the galaxies' ages, metallicities, and α-elements abundances from single stellar population models. The ionized-gas kinematics gives a valuable consistency check for the model assumptions about orientation and intrinsic shape of the galaxies. Four galaxies have a significant detection of dark matter and their halos are about 10 times denser than in spirals of the same stellar mass. Calibrating dark matter densities to cosmological simulations we find assembly redshifts z DM ≈ 1−3, as previously reported for Coma. The dynamical mass that follows the light is larger than expected for a Kroupa stellar initial mass function (IMF), especially in galaxies with high velocity dispersion σ eff inside the effective radius r eff . This could indicate a 'massive' IMF in massive galaxies. Alternatively, some of the dark matter in massive galaxies could follow the light very closely. In combination with our comparison sample of Coma early-type galaxies, we now have 5 of 24 galaxies where (1) mass follows light to 1 − 3 r eff , (2) the dynamical mass-to-light ratio of all the mass that follows the light is large (≈ 8 − 10 in the Kron-Cousins R band), (3) the dark matter fraction is negligible to 1 − 3 r eff . Unless the IMF in these galaxies is particularly 'massive' and 1

We present high quality long slit spectra along the major and minor axes out to 1.5 effective radius (R e ) of the massive galaxy NGC4636 taken by Hobby-Eberly Telescope (HET). Using Fourier Correlation Quotient (FCQ) method, we measured the stellar line-of-sight velocity distribution along the axes. Furthermore, six Lick/IDS indices (Hβ, Mgb, Fe 5015 , Fe 5270 , Fe 5335 , Fe 5406 ) are derived from the clean spectrum. By comparing the measured absorption line strengths with the predictions of Simple Stellar Populations (SSP) models, we derived ages, total metallicity and α abundance profiles of the galaxy. This galaxy presents old and [α/Fe] over abundant stellar populations. Indeed, using the SSP model, we obtained the broadband color profiles. The theoretical colors match well with the measured colors and present red sharp peaks at the galaxy center. The sharp peaks of the colors are mainly shaped by the high metallicity in the galaxy center. Interestingly, the galaxy has steep negative metallicity gradients, but trend flattens outwards. This result likly suggests that the center and outer regions of the galaxy formed through different formation process.

Abstract. We studied the stellar populations, distribution of dark matter, and dynamical structure of a sample of 25 early-type galaxies in the Coma and Abell 262 clusters. We derived dynamical mass-to-light ratios and dark matter densities from orbit-based dynamical models, complemented by the ages, metallicities, and α-element abundances of the galaxies from single stellar population models. Most of the galaxies have a significant detection of dark matter and their halos are about 10 times denser than in spirals of the same stellar mass. Calibrating dark matter densities to cosmological simulations we find assembly redshifts z D M ≈ 1 − 3. The dynamical mass that follows the light is larger than expected for a Kroupa stellar initial mass function, especially in galaxies with high velocity dispersion σ eff inside the effective radius r eff . We now have 5 of 25 galaxies where mass follows light to 1 − 3 r eff , the dynamical mass-to-light ratio of all the mass that follows the light is large (≈ 8 − 10 in the Kron-Cousins R band), the dark matter fraction is negligible to 1 − 3 r eff . This could indicate a 'massive' initial mass function in massive early-type galaxies. Alternatively, some of the dark matter in massive galaxies could follow the light very closely suggesting a significant degeneracy between luminous and dark matter.