| Abstract: |
It is well established that supermassive black holes at the centers of galaxies coevolve with the bulges of their host galaxies; however, the physicalprocesses that drive this coevolution remain unclear. In particular, understanding the mechanisms that transport gas from galactic scales (~10 kpc) down to the circumnuclear region (≲100 pc) is a key open question.In this study, we perform simulations of isolated spiral galaxies using the N-body/SPH code ASURA (Saitoh et al. 2008, 2013), focusing on three models with different bulgeto-disk mass ratios (Mbulge/Mdisk = 0.02,0.1, 0.2), to investigate the underlying mass transport processes. Our results show that steady inflow of gas into the central ≲100 pc region, at a rate of approximately 1 solar mass per year, occurs in all models and is driven by gravitational torques from stellar spiral arms. In addition, we find that, in the model with Mbulge/Mdisk = 0.02, bar-driven gravitational torques can trigger the episodic accretion of dense gas clumps (~10^7 solar mass, nH > 700 /cc) into the central region on timescales of ~10 Myr. Such rapid clump accretion is absent in the more bulge-dominated models (Mbulge/Mdisk = 0.1, 0.2), where bar instability is suppressed in the central potential. This suggests that the episodic infall of dense gas clumps via bar structures is dependent on bulge mass, and may serve as an important mechanism for delivering high-density gas to the galactic center and triggering nuclear activity in isolated spiral galaxy.If time permits, we will also discuss how such bar-induced mass transport and mass inflow driven by galaxy mergers contribute to the coevolution of SMBHs and their host galaxies, based on the latest results from galaxy interaction simulations.
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