02.10.2024
"New Physics, or a tricky model bias and degeneracy?"
Wojciech Hellwing (Center for the Theoretical Physics, PAN, Warsaw)Show abstract
Modern cosmology thanks to evergrowing precision and volume of astronomical data has become high precision science. Yet this amazing growth has come at a price. The precise observations has revealed a number of strange anomalies between the model and the data. These are commonly called "LCDM tensions" and include H0 tension, S8 tension, early galaxies problem and so on. In my talk, using some examples from my own research, I will show how such anomalies can partially and potentially be obscured by strange systematic and hidden degeneracies based on physics that wasn't even considered before the era of precision cosmology. I will also point towards possible remedies that can help us break this degeneracies and give us better understanding of the data and the cosmos.
09.10.2024
"Cosmic measures: period-luminosity relations of pulsating stars in the Sloan bands"
Weronika Narloch (CAMK, Warsaw)Show abstract
Since its discovery by Henrietta Swan Leavitt, the period-luminosity relation (also known as the Leavitt Law) for pulsating stars has been a useful tool for measuring
cosmic distances. Over time, it has become a crucial rung of the so-called extragalactic distance ladder, important for measuring the famous Hubble constant, which
can be interpreted as the rate of expansion of the universe. For this reason, period-luminosity relationships have become the object of interest for the Araucaria group.
In this talk, I would like to present our recent efforts to calibrate these relations for different types of pulsating stars in our Galaxy, in the Sloan bands.
16.10.2024
"Exploring the Central Regions of Active Galactic Nuclei"
Amit Kumar Mandal (Center for Theoretical Physics, Polish Academy of Science, Warsaw)Show abstract
This talk will focus on understanding the innermost structure of Active Galactic Nuclei (AGNs), which cannot be resolved by any existing imaging techniques, through multi-wavelength observations. The flux variability of AGN serves as a powerful tool to map the extent of both the dusty torus and the broad line region (BLR) surrounding the central supermassive black hole (SMBH). Reverberation mapping (RM) is a key technique that enables estimates of SMBH mass (M_BH) across a range of redshifts. RM relies on measuring the time delay between variations in the continuum emission and the corresponding response from the line-emitting gas and the reprocessed torus emission. In this talk, I will focus on constraining the torus size-luminosity relation in AGNs by utilizing optical data from ground-based surveys such as ASAS-SN, CRTS, PTF, and ZTF, along with infrared data from the Wide-field Infrared Survey Explorer (WISE) in the W1 and W2 bands. Additionally, I will briefly discuss accretion disk continuum reverberation mapping, which helps to determine the size of the continuum-emitting region in the accretion disk and its correlation with key AGN parameters, including luminosity and accretion rate.
23.10.2024
"An Overview of Rubin Observatory and LSST"
Knut Olsen (NOIRLab, Arizona)Show abstract
I will present an overview of the Vera C. Rubin Observatory project and its planned
Legacy Survey of Space and Time (LSST), scheduled to start in 2025. The overview will include
LSST’s science goals, the status of the construction project, the plans for operations
(including the role of the Rubin In-Kind program), and the planned observing strategy.
