Seminarium Ogólne

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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).

4 maja 2026

“Cosmic Dipole Anomaly”

prof. Roya Mohayaee
Institut d’Astrophysique de Paris, Sorbonne University, Paryż, Francja

Streszczenie:
I will review the cosmic dipole anomaly, which refers to the discrepancy between the predictions of the FLRW model and observational data. I will explain how this anomaly emerges in analyses of quasars and radio datasets, where it currently exceeds the 5\sigma significance level. I will also review that this result has withstood rigorous systematic tests and persists across multiple datasets, methodologies and analyses.

11 maja 2026

“Probing the baryon cycle of primordial galaxies in the ALMA and JWST era”

dr Prasad Sawant
Instytut Astronomii, Uniwersytet Mikołaja Kopernika

Streszczenie:
The ALMA Large Program ALPINE provides a unique multiwavelength perspective on star-forming galaxies at redshift z ~ 5, offering fundamental insights into their gas and dust content, morphological and kinematic properties, and the physical mechanisms governing their baryonic cycle. In this work, we employ chemical evolution models to investigate the co-evolution of gas and dust within this population of primordial galaxies.

We systematically explore the parameter space of dust production and destruction mechanisms, including Type II supernovae (SNII), asymptotic giant branch (AGB) stars, and grain growth within the interstellar medium (ISM) to reproduce the observed gas and dust properties across the ALPINE sample. Our models successfully account for the gas and dust content of the majority of these galaxies, pointing to SNII as the dominant dust production channel, with galactic outflows and moderate infall of gas playing a key role in regulating the overall dust budget.

A subset of galaxies, however, exhibit an anomalously rapid dust build-up on timescales of order ~ 20 – 100 Myr, which cannot be readily explained within a standard framework. We demonstrate that invoking a top-heavy initial mass function (IMF) which preferentially enhances the formation of massive stars and accelerates dust enrichment partially reconciles this tension, suggesting that variations in the stellar IMF may be a non-negligible factor in the early dust assembly of high-redshift galaxies.

Finally, I will discuss future directions enabled by the latest James Webb Space Telescope (JWST) observations and their synergies with radio continuum surveys through stacking analyses, for constructing a comprehensive picture of baryonic cycle across cosmic time.