Asia Pacific Physics Week 2023 (APPW2023)

Thursday, Nov. 9, 2023  

3:20 PM - 4:00 PM  Plenary Talk  Bobomurat Ahmedov (Ulugh Beg Astronomical Institute) 

Modern problems of relativistic astrophysics

Bobomurat Ahmedov

a Ulugh Beg Astronomical Institute, Astronomy St. 33, Tashkent 100052, Uzbekistan

b Institute of Theoretical Physics, National University of Uzbekistan, Tashkent

Institute of Fundamental and Applied Research, National Research University TIIAME, Kori Niyoziy 39, Tashkent 100000, Uzbekistan

  The branch of astrophysics that examines the behavior of matter and radiation under strong gravitational fields, as predicted by Einstein's theory of general relativity, is known as relativistic astrophysics. Several research groups and institutions in Uzbekistan, such as the Ulugh Beg Astronomical Institute of the Academy of Sciences of Uzbekistan and the National Research University, are dedicated to studying relativistic astrophysics. These institutions explore topics like black holes, neutron stars, gravitational waves, and cosmology. Their research has contributed significantly to the study of theoretical models for compact stars, gamma-ray bursts, and gravitational waves from merging black holes. Research in relativistic astrophysics in Uzbekistan has the potential to further our understanding of the universe's fundamental laws and is a significant contribution to the global scientific community [1,2].

  Recent astronomical observations, both from ground and space telescopes, have greatly expanded our understanding of celestial objects, including black holes. Although black holes are difficult to observe due to their intense gravitational pull, recent observations have provided evidence of their impact on nearby objects. For instance, black holes emit powerful gamma-ray bursts that can affect their surroundings and even trigger the formation of new stars. The intense gravitational pull of black holes can also cause nearby gas and dust to collapse, leading to the formation of new stars. Modern astronomical observations have enabled scientists to study black holes in detail, providing valuable insights into the nature of these objects and their role in the evolution of the universe.

  Studying the motion of photons around rotating black holes and analyzing their silhouettes is one of the essential tasks of modern astrophysics. International projects such as the Black Hole Cam (BHC) and the Event Horizon Telescope (EHT) have used radio astronomical observations to study the motion of photons around black holes in detail. The EHT has been instrumental in providing evidence of the existence of black holes and retrieving information about events on the central object in our galaxy. In April 2019, the EHT collaboration released the first image of the "shadow" of the supermassive black hole candidate in the galaxy M87, which confirmed many predictions made by previous studies. This groundbreaking discovery marked a significant milestone in the study of black holes and demonstrated the effectiveness of radio astronomical observations in providing proof of the existence of black holes and retrieving information about events on the central object in our galaxy.

  The field of relativistic astrophysics and cosmology has become a relevant, engaging, and important area of research globally. In Uzbekistan, research focuses on applying the principles of general relativity and alternative theories of gravity to address contemporary issues in the field of relativistic astrophysics, including electromagnetic and scalar fields, gravitational waves, and the use of satellites for ionospheric studies and positioning systems. This research aims to develop new astrophysical applications and make significant contributions to the study of relativistic astrophysics.

  I will discuss the end state of the evolution of massive stars, and various observational properties of black holes and magnetized neutron stars.  The energetics of rotating black holes and neutron stars is also in the scope of my talk.

  The numerous (more than 20) successful PhD and DSc defences in recent years in theoretical astrophysics demonstrate the rapid growth and promising future of relativistic astrophysics in Uzbekistan.

[1] Ahmedov B., Relativistic Astrophysics in Uzbekistan, Proceedings of the International Astronomical Union (2019) V. 13, Symposium S349: Under One Sky: The IAU Centenary Symposium, pp. 276–282.

[2] Ahmedov B., Development and perspectives of relativistic astrophysics in Uzbekistan. Arab. J. Math.  11 , pages 141–153 (2022).