Field spheroid-dominated galaxies in a Λ-CDM Universe

Abstract

Context. Understanding the formation and evolution of early-type, spheroid-dominated galaxies is an open question within the context of the hierarchical clustering scenario, particularly in low-density environments. Aims. Our goal is to study the main structural, dynamical, and stellar population properties and assembly histories of field spheroiddominated galaxies formed in a Λ−CDM scenario to assess to what extent they are consistent with observations. Methods. We selected spheroid-dominated systems from a Λ-CDM simulation that includes star formation, chemical evolution, and supernova feedback. The sample is made up of 18 field systems with M Star 6 × 10 10 M that are dominated by the spheroid component. For this sample we estimated the fundamental relations of ellipticals and compared them with current observations. Results. The simulated spheroid galaxies have sizes that are in good agreement with observations. The bulges follow a Sersic law with Sersic indexes that correlate with the bulge-to-total mass ratios. The structural-dynamical properties of the simulated galaxies are consistent with observed Faber-Jackson, fundamental plane, and Tully-Fisher relations. However, the simulated galaxies are bluer and with higher star formation rates than the observed isolated early-type galaxies. The archaeological mass growth histories show a slightly delayed formation and more prominent inside-out growth mode than observational inferences based on the fossil record method.Conclusions. The main structural and dynamical properties of the simulated spheroid-dominated galaxies are consistent with observations. This is remarkable since our simulation has not been calibrated to match them. However, the simulated galaxies are blue and star-forming, and with later stellar mass growth histories compared to observational inferences. This is mainly due to the persistence of extended discs in the simulations. The need for more efficient quenching mechanisms able to avoid further disc growth and star formation is required in order to reproduce current observational trends.

SDSS-IV MaNGA: Global and local stellar population properties of elliptical galaxies

“…In a general way, the results reported here for CLEs are consistent with the prediction from hydrodynamic simulations of the formation of spheroid-dominated galaxies (e.g., Naab et al 2009;Oser et al 2010;Navarro-González et al 2013;Rodriguez-Gomez et al 2016;Rosito et al 2018Rosito et al , 2019a. These simulations show that massive spheroid-dominated galaxies follow, in general, a two-phase formation scenario, which consists of an initial gas-rich (dissipational) collapse onto dark matter halos, where the bulk of the stellar mass is formed, and a late dry accretion of satellites and eventual (dry) major merger events.…”

Using angular momentum maps to detect kinematically distinct galactic components

“…We note that the D/T θ <30 • value where the demarcation (red) lines meet the median (black) lines lies lower than the 0.5 value used by some other methods (e.g. Rosito et al 2018;Tissera et al 2019;Rosito et al 2019) to separate disc-dominated from bulgedominated galaxies; and it is closer to that of, for example, Lagos, Cora & Padilla ( 2008…”

OUP accepted manuscript

“…FRs consistent with quenched star formations, as indicated by their position below the line separating active and passive galaxies according to Omand et al (2014). However, some bulge-dominated systems can still be found among starforming galaxies (Rosito et al 2018b). Also passive galaxies can have disc morphologies, but these tend to be relegated to lower mass systems.…”