Seminarium Ogólne 2025
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Seminarium odbywa się w Piwnicach w sali wykładowej budynku Radioastronomii. Początek o godzinie 11.15.
Udział w seminarium w trybie zdalnym za pośrednictwem BigBlueButton (BBB).
13 stycznia 2025
“Progenitors of LGRBs: Are single stars enough?”
mgr Rafia Sarwar (Instytut Astronomii, Uniwersytet Mikołaja Kopernika)
Streszczenie:
Stars more massive than 8 M☉ are ignited by nuclear-burning processes of chemical elements in their interiors until the formation of the carbon-oxygen core that marks the end of their life cycle. The final fate of evolved massive stars is classically linked to energetic and luminous transient sources: long-duration gamma-ray bursts (LGRBs). I present the revised and expanded single-star models using MESA and new observational comparisons in this work. My study demonstrates the impact of rotation during the evolution of these stars, leading to chemically homogeneous evolution followed by various types of supernova explosions. I also compare these theoretical models with the observed number of LGRBs to date with known redshifts. The comparison reveals that the updated massive-star physics can explain the observed distribution more fairly than previous studies, primarily due to the way mass loss from stellar winds is treated during evolution.
20 stycznia 2025
“Red novae and their remnants: how stars merge and what is the outcome”
dr hab. Tomasz Kamiński, prof. CAMK (Centrum Astronomiczne im. M. Kopernika PAN, Toruń)
Streszczenie:
Red novae are transient events powered by stellar collisions of normal (non-compact) stars. I am going to summarize recent advancements in red nova observations and in modelling of stellar mergers. For instance, I am going to briefly discuss how observations of circumstellar matter help us to identify the mechanisms that lead to a collision and fast coalescence. I am going to mention future prospects of observing red novae with LSST-Rubin and what consequences they may have. Finally, I am going to present my future project to observe the radioactive nuclide of 26Al in merger remnants and in other objects.
27 stycznia 2025
“Playing hide and seek with galaxies”
dr hab. Katarzyna Małek, prof. NCBJ (Zakład Astrofizyki, Narodowe Centrum Badań Jądrowych, Warszawa)
Streszczenie:
What is the nature of low surface brightness (LSB) galaxies? How many types of LSB galaxies exist, and how do they relate to the global mass distribution in our Universe? Furthermore, how can these galaxies be identified in existing surveys, as we now prepare for the Vera C. Rubin Legacy Survey of Space and Time, which will detect a significant number of LSB galaxies, but only in optical bands? I will present a selection of new results from our research group, including insights into their potential dust content and clustering properties, which highlight the complexity of this topic and pave the way for new discoveries.
3 lutego 2025
“Exploring blazar flares with threshold autoregressive models and spectral energy distribution modeling”
mgr Klaudia Kowalczyk (Instytut Astronomii, Uniwersytet Mikołaja Kopernika)
Streszczenie:
Blazars are a unique class of active galactic nuclei (AGNs) hosting relativistic jets pointing almost directly at the observer. They are known to be highly variable sources in all energy bands, from radio waves to very high-energy gamma rays, where they exhibit powerful flares. Their variability is assumed to originate in the jet. By modeling blazars’ spectral energy distribution (SED), we can study the innermost non-visible parts of blazars. I will present a novel method of differentiating quiescent states from flares in blazar gamma-ray light curves using the self-exciting threshold autoregressive (SETAR) model. I will also show the preliminary results of modeling blazar SEDs and linking the obtained physical parameters to different states of blazars.