Speaker: Dr. Panos Patsis (RCAAM, Academy of Athens)
Title: Why should we care about how fast spiral arms and bars of galaxies rotate? - Understanding the significance of determining their pattern speeds.
Abstract: Disk galaxies exhibit two primary morphological characteristics: bars and spiral arms. From the Dynamics standpoint, these features can be viewed as perturbations of an axisymmetric background potential. These components of galactic structure rotate at a specific angular frequency, known as the pattern speed, while the stars within the galactic disk orbit at varying velocities determined by their distance from the galactic center. I will illustrate why the pattern speed, along with the strength of the bar or spiral perturbation, is the most critical parameter governing the Dynamics and the resulting morphology of galaxies, by determining the locations of galactic resonances within the disks. The pattern speed determines the positions of the main star-forming regions in spiral galaxies and influences the inflow of gas toward the central regions. Additionally, it is influenced by the presence of Dark Matter, providing insights into its distribution around the galactic disks.
