We analyse the output of the hi-res cosmological “ zoom-in ” hydrodynamical simulation Eris BH to study self-consistently the formation of a strong stellar bar in a Milky Way-type galaxy and its effect on the galactic structure as well as on the central gas distribution and star formation .
The simulation includes radiative cooling , star formation , SN feedback and a central massive black hole wich is undergoing gas accretion and is heating the surroundings via thermal AGN feedback .
A large central region in the Eris BH disk becomes bar-unstable after z \sim 1.4 , but a clear bar-like structure starts to grow significantly only after z \simeq 0.4 , possibly triggered by the interaction with a massive satellite .
At z \simeq 0.1 the bar stabilizes and reaches its maximum radial extent of l \approx 2.2 kpc .
As the bar grows , it becomes prone to buckling instability , which we quantify based on the anisotropy of the stellar velocity dispersion .
The actual buckling event is observable at z \simeq 0.1 , resulting in the formation of a boxy-peanut bulge clearly discernible in the edge-on view of the galaxy at z = 0 .
The bar in Eris BH does not dissolve during the formation of the bulge but it is long-lived and is strongly non-axisymmetric down to the resolution limit of \sim 100 pc at z = 0 .
During its early growth , the bar exerts a strong torque on the gas within its extent 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 infalling gas is nearly all consumed into stars and , to a lesser extent , accreted onto the central black hole , leaving behind a gas-depleted region within the central \sim 2 kpc .
Observations would more likely identify a prominent , large-scale bar at the stage when the galactic central region has already been quenched .
Bar-driven quenching may play an important role in disk-dominated galaxies at all redshift .
AGN feedback is instrumental in this scenario not because it directly leads to quenching , but because it promotes a strong bar by maintaining a flat rotation curve , suppressing the density of baryons within the central kpc in the early stages of the formation of the galaxy .