Lower mass normalization of the stellar initial mass function for dense massive early-type galaxies at z ~ 1.4

Understand

This paper aims at understanding if the normalization of the stellar initial mass function (IMF) of massive early-type galaxies (ETGs) varies with cosmic time and/or with mean stellar mass density Sigma (M*/2\pi Re^2).

• For this purpose we collected a sample of 18 dense (Sigma>2500 M_sun/pc^2) ETGs at 1.2<z<1.6 with available velocity dispersion sigma_e.
• We have constrained their mass-normalization by comparing their true stellar masses (M_true) derived through virial theorem, hence IMF independent, with those inferred through the fit of the photometry assuming a reference IMF (M_ref).
• Adopting the virial estimator as proxy of the true stellar mass, we have assumed for these ETGs zero dark matter (DM).