AGN-driven quenching of star formation: morphological and dynamical implications for early-type galaxies

Abstract

In order to understand the physical mechanisms at work during the formation\nof massive early-type galaxies, we performed six zoomed hydrodynamical\ncosmological simulations of halos in the mass range 4.3 10^12 < M_vir < 8.0\n10^13 M_sun at z=0, using the Adaptive Mesh Refinement code RAMSES. These\nsimulations explore the role of Active Galactic Nuclei (AGN), through jets\npowered by the accretion onto supermassive black holes on the formation of\nmassive elliptical galaxies. In the absence of AGN feedback, large amounts of\nstars accumulate in the central galaxies to form overly massive, blue, compact\nand rotation-dominated galaxies. Powerful AGN jets transform the central\ngalaxies into red extended and dispersion-dominated galaxies. This\nmorphological transformation of disc galaxies into elliptical galaxies is\ndriven by the efficient quenching of the in situ star formation due to AGN\nfeedback, which transform these galaxies into systems built up by accretion.\nFor galaxies mainly formed by accretion, the proportion of stars deposited\nfarther away from the centre increases, and galaxies have larger sizes. The\naccretion is also directly responsible for randomising the stellar orbits,\nincreasing the amount of dispersion over rotation of stars as a function of\ntime. Finally, we find that our galaxies simulated with AGN feedback better\nmatch the observed scaling laws, such as the size-mass, velocity\ndispersion-mass, fundamental plane relations, and slope of the total density\nprofiles at z~0, from dynamical and strong lensing constraints.\n