Seminarium Zakładu Astrofizyki

Images and photon rings of accretion disks surrounding compact objects

The planet-size network of millimeter antennas Event Horizon Telescope (EHT) has recently delivered images of the surroundings of the supermassive compact object M87* at the center of the galaxy Messier 87. Such images are crucial to better understand the physics at play in a strong gravitational field environment. They might also allow to probe the extreme relativistic effects on the radiation emitted close to the compact object.

Gravitational lensing of gravitational waves: perspectives for detection and lensing rates of inspiraling double compact objects in the future gravitational wave detectors.

With the first direct detection of gravitational wave (GW) signal registered by LIGO detectors a new branch of science - GW astronomy – has been opened up. Strong success of LIGO/Virgo interferometric detectors, resulting with numerous observations of GW signals (mainly BBH coalescences), encourages to consider the possibility of broadening deca- to kilo-Hertz range of GW spectrum to lower frequencies with planned new generation of ground-based (ET) and space-borne (LISA, DECIGO) GW detectors.

Direct detections of gravitational waves (GW) opened a new era of GW astronomy

Successful GW detection and observations of coalescing binary neutron star (NS-NS) system across a spectrum of electromagnetic waves (EM) elevated multimessenger astronomy to the next stage. Future generations of GW detectors on the ground and in the space will yield a significant statistics of such events reaching up to redshift z=5 and even deeper. Non-negligible ammount of such events has a chance of being strongly lensed. I will summarize and discuss new opportunities emerging from future detections of lensed GW signals.

Mixing and Nuclear Uncertainties in Low-Metallicity AGB Stars: The Impact on Stellar Structure and Nucleosynthesis

The slow neutron-capture process(s-process) is one of the two main processes forming elements heavier than iron in stars. Its efficiency critically depends on key (a,n) reactions, which represent the main sources of neutrons to trigger the neutron-capture chain producing all elements up to bismuth, and on the modeling of convective boundaries. I present the evolution and s-process nucleosynthesis of low-mass AGB stars at low metallicities using the MESA stellar evolution code.