Angular momentum evolution for galaxies in a Λ-CDM scenario

PEDROSA, S.E.; TISSERA, P. B.

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Paris; Año: 2015 vol. 584

0004-6361

Context. Galaxy formation in the current cosmological paradigm is a very complex process in which inflows, outflows,interactions and mergers are common events. These processes can redistribute the angular momentum content ofbaryons. Recent observational results suggest that disc formed conserving angular momentum while elliptical galaxies,albeit losing angular momentum, determine a correlation between the specific angular momentum of the galaxy and thestellar mass. These observations provide stringent constraints for galaxy formation models in a hierarchical clusteringscenario.Aims. We aim to analyse the specific angular momentum content of the disc and bulge components as a function ofvirial mass, stellar mass and redshift. We also estimate the size of the simulated galaxies and confront them withobservations.Methods. We use cosmological hydrodynamical simulations that include an effective, physically-motivated Supernovafeedback which is able to regulate the star formation in haloes of different masses. We analyse the morphology andformation history of a sample of galaxies in a cosmological simulation by performing a bulge-disc decomposition of theanalysed systems and their progenitors. We estimate the angular momentum content of the stellar and gaseous discs,stellar bulges and total baryons.Results. In agreement with recent observational findings, our simulated galaxies have disc and spheroid componentswhose specific angular momentum contents determine correlations with the stellar and dark matter masses with thesame slope, although the spheroidal components are off-set by a fixed fraction. The average angular momentum efficiencyfor the simulated discs is η ∼ 1 while bulges is η ∼ 0.10 − 0.20. For the simulated sample, the correlations found forthe specific angular momentum content as a function of virial mass or stellar mass are found not to evolve significantlywith redshift (up to z ∼ 2). Both dynamical components seem to move along the correlations as they evolve. The totalspecific angular momentum of galaxies occupy different positions filling the gap between pure rotational-dominated anddispersion-dominated systems. The scaling relations derived from the simulated galaxies determine a similar relationwith the virial radius, in agreement with recent observations.