http://arxiv.org/abs/1906.11161
We study the behavior of the dynamical and stellar mass inside the effective radius of early-type galaxies (ETGs) as a function of environment considering Newtonian dynamics, different surface–brightness profiles, different initial mass functions (IMF) and different redshift ranges. We use several samples of ETGs –ranging from 19,000 to 98,000 objects– from the ninth data release of the Sloan Digital Sky Survey. We assume that any difference between the dynamical and stellar mass is due to dark matter and/or a non-universal IMF. The main results, considering samples in the redshift range 0.0024 $\leq\;z\;\leq$ 0.35 are: (i) the amount of dark matter inside ETGs depends on the environment; (ii) ETGs in low density environments span a wider dark matter range than ETGs in dense environments; (iii) the amount of dark matter inside ETGs in the most dense environments will be less than approximately 55\%–75\% of the dynamical mass; (iv) the accurate value of this upper limit depends on the impact of the IMF on the stellar mass estimation; (v) in the case of an ETGs sample which is approximately complete for log$({\bf M_{Virial}}/{\bf M_{Sun}}) > 10.5$ and in the redshift range 0.04 $\leq\;z\;\leq$ 0.08 we find that the amount of dark matter in the most dense environments will be less than approximately 60\%–65\% of the dynamical mass.
A. Nigoche-Netro, G. Ramos-Larios, P. Lagos, et. al.
Thu, 27 Jun 19
29/62
Comments: 15 pages, 7 figures. Accepted by MNRAS