Stellar structures in nearby galaxies: archaeological traces of past evolution processes

Stellar structures in nearby galaxies: archaeological traces of past evolution processes

Stellar structures are closely connected to galaxy formation and evolution, holding evidence of different evolutionary processes. Present-day disc galaxies are described as having evolved in a two-phase scenario: at first, mergers and interactions (i.e., external process) are the main drivers of galaxy evolution, shaping turbulent morphologies and building up dispersion-dominated central structures, i.e., classical bulges. At a later stage, galaxies experience fewer interactions and are less affected by them, which allows them to settle into a mature disc. Shortly after, bars are prone to form, occupying almost 70% of disc galaxies in the local Universe and driving the internal evolution of the galaxy since z~2-4. Concurrently, bars drive the formation of rotation-supported central structures, i.e., nuclear discs. In summary, classical bulges are connected to early evolution, mostly due to external factors, while bars and nuclear discs are manifestations of internal secular evolution that takes place later on.

In this talk, I will focus on two aspects of galaxy evolution in disc galaxies: (i) the first census of central structures from kinematic tracers and (ii) the first measurements of bar ages in nearby galaxies. I will present the results from BANG (Bulge Assembly of Nearby Galaxies), in which we classified kinematically the central structure of 70 galaxies observed with MUSE, constraining the relative importance between classical bulges and nuclear discs, and their dependence on the stellar mass of the host galaxy. Additionally, I will show the first methodology from which we derive the dynamical formation of nearby galaxies for the TIMER sample, connected to disc emergence, from a Local Universe perspective.

Sebastián López
Coordinador de Coloquios
DAS/UChile  – slopez@das.uchile.cl