Wednesday Colloquium


"WD binaries in MOCCA - comparisons to close and wide observed binaries"

Lukas Hellström (CAMK, Warsaw)


"CAMK Annual Conference (till Feb. 2nd)"



"News from the M87* black hole"

Maciej Wielgus (Max Planck Institute for Radio Astronomy (Bonn, Germany))

In 2017 Event Horizon Telescope (EHT), a global array of radio telescopes, observed the giant supermassive black hole M87* in the center of the M87 galaxy. These observations resulted in the first image of a black hole resolved at the event horizon scale. We have now completed the analysis of the corresponding data, with results on total intensity (2019), linear polarization (2021), and circular polarization (2023). It is a good time to summarize and systematize what we have learned about black holes, accretion disks, and magnetic fields from the EHT observations. Moreover, I will discuss the most recent first EHT results from 2018 observations of M87*, allowing us to study the persistence and variability of the black hole shadow image.


"Quantum computers — tiny universes at our command"

Piotr Gawron (CAMK/Astronet, Warsaw)

Quantum computing is at the same time a fascinating model of computation that uses the fundamental principles of Nature; great engineering challenge; and a promise of calculating the impossible and acquiring unimaginable riches. During the talk we will try to present what quantum computing really means, what it is not, what are hopes related to and what are the challenges in implementation of quantum computing. We will show simultaneously how little is possible to achieve with quantum computers today and how unimaginably marvellous the quantum computers — those tiny universes at our command — are.


"Multiple Stellar Populations - Speculations on Cluster Migration and Gas Re-Accretion"

Mirosław Giersz (CAMK, Warsaw)

I will very briefly discuss the formation and evolution of multiple populations in globular clusters from the point of view of observation and theory. Then I will present the main scenarios of their formation and discuss their weaknesses. Finally, I will focus on describing the results of simulations carried out with the MOCCA Monte Carlo code and summarize the conclusion resulting from these simulations in the form of a speculative scenario.


"Propagation and lensing of gravitational waves in modified theories"

Sreekanth Harikumar (National Center for Nuclear Research, Warsaw)

The first direct detection of gravitational waves by LIGO collaboration has opened a new era of Gravitational Wave astronomy. The bending of light by massive objects is a prediction of General Relativity (GR) and this phenomenon known as gravitational lensing has now become an indispensable tool in astrophysics. Therefore, in this era of astronomy, the next most anticipated event is the detection of gravitational waves lensed by massive sources along the line of sight. The lensed gravitational waves has many applications such as detection of Intermediate Mass BlackHoles (IMBH), Primordial Black Holes, precision cosmology etc. Another emerging avenue is the test of GR, in this talk I will discuss the predictions of f(R) and Palatini f(R) in the context of lensing of gravitational waves.



Young astronomers meeting at CAMK (CAMK, Warsaw)


"TESS photometry of hot subdwarf stars"

Sumanta Kumar Sahoo (CAMK, Warsaw)

Hot subdwarf stars are extreme horizontal branch stars, consisting of a convective helium-burning core, helium shell, and a thin (in mass) hydrogen envelope. A few of these subdwarfs pulsate, which opens the window to study these stars using asteroseismology. The majority of such pulsating stars detected are B-type stars (sdBV). From the TESS mission, we have detected a few tens of rich gravity mode sdBVs by analyzing their short cadence (SC) light curves and identified their pulsation mode geometries. Apart from the SC data, we also extracted light curves from TESS full frame images for the targets not observed in SC mode and analyzed them to detect pulsations. I will be talking about these pulsating subdwarf stars and our study to understand their pulsation properties.



Jonas Pereira