Theoretical Astrophysics Group
The Theoretical Astrophysics Group at the Niels Bohr International Academy strives for a comprehensive approach to astrophysics. Current research areas encompass star and planet formation, protoplanetary disks and black hole accretion disks, the intracluster medium in galaxy clusters, as well the physics of gravitational waves sources.
We have strong ties to the Computational Astrophysics Group in the Astrophysics and Planetary Science Group at the Niels Bohr Institute.
Accretion Disks are flattened, differentially rotating gaseous structures that can be found surrounding young stars, white dwarfs, neutron stars, and black holes.
Understanding the physical processes that determine the rate at which matter accretes and energy is radiated in these disks is vital for unraveling the formation, evolution, and fate of almost every type of object in the Universe. We work on several fundamental problems related to the the physical structure and observational properties of these disks. This undertaking entails theoretical and numerical efforts for understanding and modeling the interplay between the generation of magnetized turbulence, the global structure of the accretion disc, and the high-energy radiative processes taking place in the disc and its corona.
Chondrules are spherical grains of silicate material with diameters ~ 1 mm and constitute a ubiquitous class of materials found in primitive meteorites. Their spherical shape and internal textures suggest that they were produced by the rapid melting and slow cooling of silicate dust. Understanding the formation of chondrules has been a long standing problem in cosmo-chemistry with profound implications for the formation and early evolution of the solar system and extra-solar planetary systems. We are currently working on understanding physically viable mechanisms behind the inferred rapid local heating. This requires elucidating, and simulating, the nonlinear dynamics of a mixture of gas and dust, including the ionization, chemistry, and radiative transfer properties.
Galaxy Clusters can contain several hundred galaxies. Their masses, mostly comprised of dark matter, are in the range of 1014 to 1015 solar masses and they can extend up to 106 to 107 light years.
These are the largest gravitationally bound objects in the Universe. Unravelling the dynamical properties of the dilute magnetized plasma that permeates galaxy clusters is of paramount importance for cosmology and astrophysics. In particular, understanding the physical mechanisms that dictate the gas dynamics and keep the plasma hot (up to 106 to 107 K!) has been a major challenge in astrophysics for several decades. We are working on understanding a variety of instabilities that can be driven by temperature or composition gradients present in the intra-cluster medium.
News on Astrophysics
Danish participation in over a third of the new James Webb Space Telescope’s initial observations
New study shows doubt about the composition of 70 percent of our universe
Dr. Martin E. Pessah
Professor MSO, Deputy Director
Niels Bohr International Academy
Niels Bohr Institute
Blegdamsvej 17, 2100
Tel: + 45 35 32 53 12
Fax: + 45 35 32 50 16
|Benitez Llambay, Pablo||Assistant Professor|
|D'Orazio, Daniel J||Assistant Professor|
|Heinemann, Tobias Peter||Associate Professor|
|Pessah, Martin Elias||Professor with special responsibilities||+4535325312|
|Samsing, Johan Georg Mulvad||Assistant Professor||+4535320370|
External staff & students
|Oliver Gressel||Associate professor|