Miljenko Čemeljić (CAMK, Warsaw)
In analogy with the Solar system planets, we predict the existence of aurora on planets around millisecond pulsars. From our magnetohydrodynamic (MHD) simulations of magnetospheric pulsar-planet interaction, we estimate the radio emission from such systems. We find that the radio emission from aurora on pulsar planets should be observable with the current instruments, and provide parameters for such a detection. It would be the first radio detection of an extrasolar planet and the first direct probe in the pulsar wind.
Hareesh Thuruthipilly (National Center for Nuclear Research, Warsaw)
Low surface brightness galaxies (LSBGs) which are defined as galaxies that are fainter than the night sky, play a crucial role in understanding galaxy evolution and cosmological models. Upcoming large-scale surveys like Rubin Observatory Legacy Survey of Space and Time (LSST) and Euclid are expected to observe billions of astronomical objects. In this context, using semi-automatic methods to identify LSBGs would be a highly challenging and time-consuming process and demand automated or machine learning-based methods to overcome this challenge. We study the use of transformer models in separating LSBGs from artefacts in the data from the Dark Energy Survey (DES) data release 1. Using the transformer models, we search for new LSBGs from the DES that the previous searches may have missed. We identified 4,083 new LSBGs in DES, adding an additional 17% to the LSBGs already known in DES. This also increased the number density of LSBGs in DES to 5.5 deg^{-2}. Properties of the newly found LSBGs are investigated, along with an analysis of the properties of the total LSBG sample in DES.
Marzena Śniegowska (Tel Aviv University and CAMK PAN)
Apart from regular, low-level stochastic variability, some AGNs occasionally show exceptionally large changes in luminosity, spectral shape, and/or X-ray absorption that occur on surprisingly short timescales (even several weeks). The most notable are the changes of the spectral type when the source classified as a Seyfert 1 becomes a Seyfert 2 galaxy or vice versa. Thus a name was coined as 'Changing-Look AGN' (CL AGN). The origin of this phenomenon is still unknown, but for most of the sources, there are strong arguments in favor of intrinsic changes. Understanding the nature of such rapid changes is a challenge to the models of black hole accretion flows since the timescales of the changes are much shorter than the standard disk viscous timescale, related to changes in angular momentum distribution. I will present recent results regarding the model of the time-dependent evolution of a black hole accretion disk unstable due to the dominant radiation pressure as the CL AGN phenomenon scenario. I will discuss also poorly understood flaring AGN with broad Bowen fluorescence emission features, driven by extreme UV radiation that appears within weeks but lasts for well over a year. Those events observationally differ from the tidal disruption events known to date, however, the physics behind them may be interlinked.
Stefanie Komossa (Max-Planck-Institute for Radio Astronomy, Bonn)
Highly variable and transient active galactic nuclei (AGN) provide us with important insights into the physics of accretion of matter onto their central supermassive black holes (SMBHs). This talk discusses some of the most extreme cases of variability so far observed among AGN, including the highest-amplitude X-ray--optical outbursts, deep-minima states, and exceptional optical emission-line changes, and their interpretation, based on observations taken at mutiple wavebands from the radio to the X-ray regime. A fraction of AGN harbor binary SMBHs at their centers. Upon final coalescence, these are the loudest sources of gravitational waves in the universe. After a brief introduction of the topic, I will then discuss the best-known case of a compact binary SMBH candidate, hosted by the blazar OJ 287. In the course of the project MOMO, we have carried out the densest, longest, multi-wavelength monitoring project of OJ 287 done so far from radio to high energies, and I will highlight key results and implications for binary SMBH scenarios.
