# Secular evolution and pseudo-bulges

## TL;DR

This paper discusses how bars induce pseudo-bulge formation through secular evolution, examines gas inflow and nuclear activity in galaxies, and highlights recent high-resolution observations of black hole environments.

## Contribution

It provides insights into the mechanisms of pseudo-bulge formation, the role of gravity torques in gas inflow, and the application of ALMA observations for studying black hole surroundings.

## Key findings

- Bars can produce pseudo-bulges via vertical resonances.
- Only about one third of Seyfert galaxies show molecular inflow at certain scales.
- ALMA enables detailed study of black hole influence and circum-nuclear structures.

## Abstract

Through vertical resonances, bars can produce pseudo-bulges, within secular evolution. Bulges and pseudo-bulges have doubled their mass since z=1. The frequency of bulge-less galaxies at z=0 is difficult to explain, especially since clumpy galaxies at high z should create classical bulges in all galaxies. This issue is solved in modified gravity models. Bars and spirals in a galaxy disk, produce gravity torques that drive the gas to the center and fuel central star formation and nuclear activity. At 0.1-1kpc scale, observations of gravity torques show that only about one third of Seyfert galaxies experience molecular inflow and central fueling, while in most cases the gas is stalled in resonant rings. At 10-20pc scale, some galaxies have clearly revealed AGN fueling due to nuclear trailing spirals, influenced by the black hole potential. Thanks to ALMA, and angular resolution of up to 80mas it is possible to reach the central black hole (BH) zone of influence, discover molecular tori, circum-nuclear disks misaligned with the galaxy, and the BH mass can be derived more directly from the kinematics.