Secular evolution of Milky Way-type galaxies

TL;DR

This paper explores the internal secular processes in Milky Way-like galaxies, including bar dynamics, gas flows, and black hole activity, revealing how these mechanisms shape galaxy evolution over time.

Contribution

It provides a comprehensive analysis of the secular evolution mechanisms in disk galaxies, emphasizing the roles of bars, gas inflows, and nuclear activity in galaxy transformation.

Findings

Formation of secondary bars due to mass concentration

Development of box/peanut bulges via vertical resonances

Intermittent black hole accretion and AGN cycles

Abstract

The internal evolution of disk galaxies like the Milky Way are driven by non-axisymmetries (bars) and the implied angular momentum transfer of the matter; baryons are essentially driven inwards to build a more concentrated disk. This mass concentration may lead to the decoupling of a secondary bar, since the orbit precessing frequency is then much enhanced. Vertical resonances with the bar will form a box/peanut bulge in a Gyr time-scale. Gas flows due to gravity torques can lead to a young nuclear disk forming stars, revealed by a sigma-drop in velocity dispersion. These gas flows moderated by feedback produce intermittent accretion of the super-massive black hole, and cycles of AGN activity. The fountain effect due to nuclear star formation may lead to inclined, and even polar nuclear disks.