Special Colloquium
Prof. Laurent Loinard	SCHEDULED

National University of Mexico

Gaia and phase-referenced VLBI observations deliver similar levels of astrometric accuracy - of order 20 micro-arcseconds on trigonometric parallax measurements. The two types of measurements, however, are affected by different sources of error and have different limitations. Gaia, of course, provides results for more than a billion objects while VLBI astrometric observations exist only for a few hundred sources. On the other hand, VLBI observations are largely immune to dust extinction, enabling observations deep into the Galactic disk. Also, the angular resolution of VLBI observations is more than a hundred times better than Gaia's, enabling the resolution of tight binary systems that cannot be resolved with Gaia. In this talk, I will present a comparison between Gaia and VLBI emphasizing the complementarity between the two techniques. I will also briefly touch on expected VLBI astrometry improvements in the coming few decades.

	Main Colloquium
Prof. Zakaria Meliani	SCHEDULED

Observatoire de Paris

Relativistic jets in radio-loud active galactic nuclei (AGN) are fascinating astrophysical phenomena that emit non-thermal radiation across the electromagnetic spectrum and display diverse characteristics at different scales. With their frequent high flux variability, they are ideal objects to study high-energy physical processes. In this presentation, we conduct a comprehensive investigation of the intrinsic properties of relativistic jets and their impact on dynamics, interaction with the external medium, and resulting observed light curve.To explore the properties of relativistic jets, we employ a combination of relativistic magneto-hydrodynamic (MHD) simulations using the MPI-AMRVAC code and radiative transfer simulations with the post-processing code REPTIDE. We focus on the impact of various intrinsic properties of the jet, such as magnetization, rotation profile, and transverse structure and variability, on the formation, evolution, and behavior of standing knots and their interaction with moving knots. We also examine the observables associated with these features and their connection to observed variabilities at different wavelengths.

	Main Colloquium
Dr. Maria Rioja	CANCELED

ICRAR-UWA/CSIRO, OAN, Australia

TBD