Andrzej Zdziarski (Copernicus Astronomical Center, Warsaw)
The most spectacular jets are observed from active galactic nuclei, in particular, from quasars. However, highly interesting jets are also launched by accretion flows in stellar binaries containing a normal star accreting onto a stellar-mass black hole. Such systems are analogs of quasars on a much smaller scale and are called microquasars. There are two distinctly different types of jets in microquasars. Jets of the first type are steady and are launched during accretion states characterized by hard X-ray emission. They are launched over weeks to months but are observed only up to maximum distances of about 1/1000 of a parsec. Those of the other type are launched on time scales of only a day during transitions of the accretion flow from the hard to soft spectral states but are observed as moving ejecta up to a parsec scale, i.e., up to ~1000 times larger distances. I will discuss possible causes of this difference, the jet emission mechanisms, collimation, the presence of electron-positron pairs, magnetic fields, bulk Lorentz factors, and the jet power.
Jarosław Duda (Jagiellonian University, Cracow)
I will discuss possibility of negative radiation pressure e.g. from astronomical objects and how we could observe it, also its different potential applications like medical and computational e.g. 2WQC (two-way quantum computers). Photon sources create positive radiation pressure p=
Surajit Kalita (Warsaw University Observatory)
Fast Radio Bursts (FRBs) are millisecond radio transients with high dispersion measures, making them powerful tracers of ionized matter across cosmological distances. In this talk, I present two complementary approaches, Bayesian analysis and machine learning, applied to a set of localized FRBs to rigorously test the consistency of the $\Lambda$CDM model at late cosmic epoch. Our results reveal a redshift-dependent variation in the inferred Hubble constant, a behavior that stands in contradiction to the core postulate standard cosmology. I will further show that this discrepancy can be resolved for alternate cosmological models. These findings suggest a fundamental inadequacy in the standard cosmological framework and necessitate a deeper revision of the theoretical underpinnings of cosmology to resolve the Hubble tension.
Mirosław Kicia (CAMK PAN, Warsaw)
Observatory software system is a critical component of modern astronomical facilities, ranking just below telescopes and instruments in importance. The level of automation achieved through software development directly influences the scientific productivity of an observatory by affecting the quality and usability of collected data. The presentation focuses on the software system developed for the Rolf Chini Cerro Murphy Observatory (OCM), located in the Chilean Atacama Desert. Originally established as a collaboration between the Catholic University of the North (UCN) and Ruhr University Bochum (RUB), the observatory later integrated into the Araucaria Project and the Nicolaus Copernicus Astronomical Center of the Polish Academy of Sciences (CAMK) institution. The modern phase of the observatory, beginning in 2020, involved substantial upgrades to telescopes, instruments, and infrastructure, where shortly will operates all of planned five telescopes, ranging from 0.6 m to 2.5 m in diameter. The observatory software was developed to integrate systems with new solutions, improve reliability, and bring control systems up to state-of-the-art standards. Increased automation and computerization, including the use of ML and AI methods, were implemented to address the objectives of the modern observatory systems, resulting flexible platform that supports both current and future scientific goals of the OCM, CAMK and Araucaria group.
Pratik Dabhade (National Center for Nuclear Research (NCBJ), Warsaw)
Extragalactic radio sources powered by active galactic nuclei (AGN) are extraordinary signposts of cosmic evolution. They trace the growth of supermassive black holes, shape their host galaxies through feedback, and illuminate the magnetised filaments of the large-scale cosmic web. In this seminar, I will present an overview of my research on these systems, spanning a wide range of scales and epochs - from giant and double-double radio galaxies in the nearby Universe to powerful high-redshift quasars and rare, unusual sources such as Odd Radio Circles. Through these studies, we gain insight into jet physics, episodic activity, and environmental influence. I will also discuss the role of modern radio continuum surveys - from LOFAR, MeerKAT, ASKAP, and the JVLA to the upcoming SKA, in transforming our understanding of the radio Universe. These surveys now offer unprecedented sensitivity and resolution across wide frequency ranges, enabling population studies of diverse extragalactic radio sources from star-forming galaxies and AGN to large-scale diffuse structures with a level of detail never achieved before. Finally, I will introduce the recently approved DHRUV survey, the first deep, wide-sky survey with the upgraded GMRT (uGMRT), designed to map the Euclid Deep Field North at unprecedented depth. This project aims to bridge the observational gap between LOFAR and GHz facilities, offering new opportunities to probe galaxy and AGN evolution, cosmic magnetism, feedback, and large-scale structure formation. Together, these efforts form a coherent framework for understanding how radio AGN connect small-scale jet physics to the grand structure of the Universe, setting the stage for the next generation of discoveries with the SKA.
