Description: We present a new zoom-in hydrodynamical simulation, ‘Eris BH ’, which features the same initial conditions, resolution, and sub-grid physics as the close Milky Way-analogue ‘Eris’ (Guedes et al. 2011 ), but it also includes prescriptions for the formation, growth and feedback of supermassive black holes. This enables a detailed study of black hole evolution and the impact of active galactic nuclei (AGN) feedback in a late-type galaxy. At z = 0, the main galaxy of Eris BH hosts a central black hole of 2.6 x 10 6 M , which correlates to the bulge mass and the galaxy's central velocity dispersion similarly to what is observed in the Milky Way and in pseudobulges. During its evolution, the black hole grows mostly through mergers with black holes brought in by accreted satellite galaxies and very little by gas accretion (due to the modest amount of gas that reaches the central regions). AGN feedback is weak and it affects only the central $1\text{--}2 \,\rm {kpc}$ . Yet, it limits the growth of the bulge, which results in a rotation curve that, in the inner ~ 10 kpc, is flatter than that of Eris. We find that Eris BH is more prone to instabilities than Eris, due to its smaller bulge and larger disc. At z ~ 0.3, an initially small bar grows to be of a few disc scalelengths in size. The formation of the bar causes a small burst of star formation in the inner few hundred pc, provides new gas to the central black hole and causes the bulge to have a boxy/peanut morphology by z = 0.

Description: We study the statistics and cosmic evolution of massive black hole seeds formed during major mergers of gas-rich late-type galaxies. Generalizing the results of the hydrosimulations from Mayer et al., we envision a scenario in which a supermassive star can form at the centre of galaxies that just experienced a major merger owing to a multiscale powerful gas inflow, provided that such galaxies live in haloes with masses above 10 11 M , are gas rich and disc dominated, and do not already host a massive black hole. We assume that the ultimate collapse of the supermassive star leads to the rapid formation of a black hole of 10 5 M following a quasi-star stage. Using a model for galaxy formation applied to the outputs of the Millennium Simulation, we show that the conditions required for this massive black hole formation route to take place in the concordance cold dark matter model are actually common at high redshift and can be realized even at low redshift. Most major mergers above z  ~ 4 in haloes with mass 〉10 11 M can lead to the formation of a massive seed and, at z  ~ 2, the fraction of favourable mergers decreases to about half. Interestingly, we find that even in the local universe a fraction (~20 per cent) of major mergers in massive haloes still satisfies the conditions for our massive black hole formation route. Those late events take place in galaxies with a markedly low clustering amplitude, that have lived in isolation for most of their life and that are experiencing a major merger for the first time. We predict that massive black hole seeds from galaxy mergers can dominate the massive end of the mass function at high ( z  〉 4) and intermediate ( z  ~ 2) redshifts relative to lighter seeds formed at higher redshift, for example, by the collapse of Pop III stars. Finally, a fraction of these massive seeds could lie, soon after formation, above the M BH - M Bulge relation.

Description: We analyse the outputs of the cosmological ‘zoom-in’ hydrodynamical simulation ErisBH to study a strong stellar bar which naturally emerges in the late evolution of the simulated Milky Way-type galaxy. We focus on the analysis of the formation and evolution of the bar and on its effects on the galactic structure, the gas distribution and the star formation. A large central region in the ErisBH disc becomes bar unstable after z ~ 1.4, but a clear bar starts to grow significantly only after z ~= 0.4, possibly triggered by the interaction with a massive satellite. At z ~= 0.1, the bar stabilizes and reaches its maximum radial extent of l 2.2 kpc. As the bar grows, it becomes prone to buckling instability. The actual buckling event, observable at z ~= 0.1, results in the formation of a boxy-peanut bulge clearly discernible at z = 0. During its early growth, the bar exerts a strong torque on the gas and drives gas inflows that enhance the nuclear star formation on sub-kpc scales. Later on, as the bar reaches its maximum length and strength, the gas within its extent is nearly all consumed into stars, leaving behind a gas-depleted region in the central ~2 kpc. Observations would more likely identify a prominent, large-scale bar at the stage when the galactic central region has already been gas depleted, giving a hint at the fact that bar-driven quenching may play an important role in the evolution of disc-dominated galaxies.