Our research

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Compact stars in our Universe are the neutron stars, white dwarfs, and black holes.

The black holes of several solar masses are formed after the collapse of a massive star at the end of its life, when the nuclear fuel is exhausted and the supernova explodes. The supermassive black holes are sitting in the centers of active galaxies and in quasars. They have probably grown via  the hierarchical sequence of mergers, from the seed black holes that formed just after the first stars were born. The primordial black holes which are the results of density fluctuations in the early universe, may also contribute to the compact object population.

The stellar mass black holes reside frequently in binary systems with main sequence stars, or with giants. They capture matter from their companions and accrete it with a rate of about one-millionth of a Solar mass per year. The rotating material forms a disk structure in the equatorial plane of such system. Due to the viscous shearing, the plasma in the disk is heated to high temperatures and the source is emitting X-ray radiation.

The stellar mass (or medium-mass) black holes are finally present in the engines of gamma ray bursts. These are transient events, which appear on the high-energy sky almost every day, and bring gamma ray photons from the most distant parts of the universe. The powerful explosions responsible for these sources are connected with the birth of new black holes and accretion of matter onto it with a rate of about one Solar mass per second. The accretion onto a fast spinning black hole and high magnetisation of the plasma is presumably a mechanism which drives the launching of ultra-fast jest ejected along the line of sight towards observer. The kinetic energy in these jets is transformed into the gamma-ray radiation.

In our research, the high-energy astrophysics group at CFT studies the black holes in the Universe in all scales of masses. We are modelling the processes of black hole accretion and plasma ejection through numerical simulations, and we confront the results of our modelling with the phenomena observed in the high energy sky.

Scroll-Down the pop-up menu from this site, to learn more about our results, see the figures and animations. Particular topics include:

  • Black hole accretion with small angular momentum
  • Black hole mass determination in HLX-1
  • Black hole mergers and gravitational waves
  • Chaotic motion around black holes
  • Formation of relativistic jets in Short Gamma Ray Bursts
  • Gamma ray bursts – neutrino cooled accretion flow
  • Magnetic field in the accreting torus around the spinning black hole in Kerr metric
  • Microquasar IGR J-17091-3624 – simulations of the unstable accretion disk
  • Nucleosynthesis of r-process elements in GRB engines
  • Revealing the deterministic chaos in X-ray lightcurves of accreting black holes
  • Shocks in the relativistic transonic accretion with low angular momentum
  • Spherical accretion onto black hole
  • Stability of Iron-opaque accretion disks


 


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