Angular momentum evolution of galaxies in EAGLE

Abstract

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The role of mergers and halo spin in shaping galaxy morphology

“…Fall 1983;Romanowsky & Fall 2012;Obreschkow & Glazebrook 2014), as well as in hydrodynamic simulations of a ΛCDM cosmology (e.g. Genel et al 2015;Teklu et al 2015;Sokolowska et al 2016;Lagos et al 2017b). We caution, however, that most of the stellar angular momentum in Illustris galaxies with M * 10 11 M is found at very large radii, which means that the total stellar angular momentum does not directly measure the degree of rotational support in the central, most luminous regions of such galaxies.…”

Quantifying the impact of mergers on the angular momentum of simulated galaxies

“…We will refer to these measurements as 'mean radial j stars profiles'. Lagos et al (2017) showed that j stars (r 50 ), calculated with all particles within the half-stellar mass radius r 50 , converges in EAGLE at M stars 10 9.5 M , and thus, we limit our sample only to galaxies with stellar masses above that threshold. Schaller et al (2015a) showed that the stellar mass radial profiles of galaxies in EAGLE are well converged to scales of at least ≈1.5 pkpc.…”

“…These results suggest that galaxy mergers can have a devastating effect on the specific AM of galaxies, but with the exact effect strongly depending on the nature of the merger. Lagos et al (2017) found that the positions of galaxies in the j stars (r 50 )-M stars plane are strongly correlated with a galaxy's gas fraction, stellar age, stellar concentration, optical colour and V/σ , all of which are usually used to distinguish early-and late-type galaxies. In Fig.…”

“…Recently, using the EAGLE simulations, Zavala et al (2016) showed that the AM loss of a galaxy's stellar component follows closely that of the inner parts of its haloes, which would be naturally explained by the merging activity of haloes and galaxies at low redshifts. Using the same simulations, Lagos et al (2017) found that mergers were not the only ones responsible of small spins, but that galaxies could also have low j stars due to early quenching.…”

The evolution of the star formation rate function in the EAGLE simulations: a comparison with UV, IR and Hα observations from z ∼ 8 to z ∼ 0

“…It has been calibrated to reproduce observational data sets, such as the present-day stellar mass function of galaxies, the correlation between the BH and masses and the dependence of galaxy sizes on mass. Alongside with these key properties, the simulation was able to match many other observed properties of galaxies at various eras, like molecular hydrogen abundances (Lagos et al 2015), colours and luminosities at z ∼ 0.1 (Trayford et al 2015), supermassive black hole (SMBH) mass function (Rosas-Guevara et al 2016), angular momentum evolution (Lagos et al 2017), atomic hydrogen abundances (Crain et al 2017) and sizes (Furlong et al 2017). Therefore the EAGLE simulations can provide a powerful resource for understanding the SFRs of galaxies and their evolution across cosmic time.…”