The Influence of Baryonic Matter on Galaxy Formation - Filler *

Galaxy formation is a complex process driven by the interplay of dark matter and baryonic matter. While dark matter halos provide the gravitational scaffolding for galaxies, baryonic matter, through its ability to cool, condense, and form stars, plays a crucial role in shaping the observable properties of galaxies. 

This article reviews the fundamental mechanisms by which baryonic matter influences galaxy formation, including gas cooling, star formation, feedback processes, and their impact on galaxy morphology, stellar populations, and the distribution of dark matter. We discuss the current theoretical frameworks and observational evidence supporting these interactions, as well as the outstanding challenges in fully understanding the intricate co-evolution of baryonic and dark matter components.

The standard cosmological model, ΛCDM (Lambda Cold Dark Matter), posits that the universe is dominated by dark energy and cold dark matter, with baryonic matter (protons, neutrons, electrons) constituting only a small fraction of the total mass-energy density (≈5%). 

Despite its minority status, baryonic matter is responsible for all observable structures in the universe, including stars, planets, and galaxies. The formation and evolution of galaxies are thus intimately linked to the behavior of baryonic matter within the gravitational potential wells provided by dark matter halos.

Early models of galaxy formation primarily focused on the hierarchical assembly of dark matter halos. However, these models often struggled to reproduce the observed properties of galaxies, such as their sizes, luminosities, and morphologies, without incorporating the complex physics of baryons. 

The key difference between dark matter and baryonic matter lies in their non-gravitational interactions: baryonic matter can dissipate energy through radiative cooling, form stars, and be influenced by feedback processes from these stars and active galactic nuclei (AGN). These processes fundamentally alter the distribution of matter and energy within galaxies, leading to the diverse galactic population we observe today.