Seminarium Zakładu Astrofizyki

Exploring the free-floating planet population with gravitational microlensing

Thousands of extrasolar planets have been discovered up to date. Although many of the known exoplanets do not resemble those in our solar system, they have one thing in common - they all orbit a star. However, theories of planet formation and evolution predict the existence of free-floating planets, gravitationally unattached to any star.

Status of the Concordance Model of Cosmology


I review the status of the concordance (standard) LCDM model of cosmology in light of current observations discussing about the apparent tensions in estimation of the key cosmological parameters. I will also briefly discuss the future of the field at the era of the next generation of astronomical/cosmological surveys.




            Serdecznie zapraszam,

               Agnieszka Majczyna

Magnetic reconnection in application to relativistic jets of active galaxies

Certain active galaxies produce powerful jets with relativistic velocities, which emit highly anisotropic non-thermal radiation. In case that a jet is directed towards an observer, the observed luminosity of its radiation exceeds significantly the luminosity of the host galaxy; such objects are called blazars. Observations of blazars indicate very efficient mechanisms of energy dissipation and non-thermal particle acceleration. The inner sections of jets are most likely relativistically magnetised, i.e., the magnetic energy density exceeds the rest-mass energy density of the matter.

The early death of cosmic giants

The majority of the stars in the local Universe belong to massive, red, spheroidal, old galaxies that died several billion years ago, ceasing their active formation of new stars. In our current view, these galaxies experienced an intense burst of growth immediately followed by a sudden death early in the Universe, so that we routinely observe a numerous population of such dead cosmic giants already in place 10 Gyr ago at z~2, comfortably reproduced by the most recent galaxy formation models and simulations.

A new graph-theory based FOF group finder and its application to the updated 2MRS

We present the galaxy group catalog for the newly completed 2MASS Redshift Survey up to a magnitude limit of K < 11.75. Consisting of ~ 45 000 redshifts, including 1 041 previously unpublished
redshifts mostly distributed along the Zone of Avoidance. The galaxy group catalog is generated by using a novel, graph theory based, modified version of the friends-of-friends algorithm. The results and

Co-evolution of galaxies and the multi-scale cosmic web at high redshift: from predictions to observations

The multi-scale cosmic web is the environment in which galaxies form and evolve. Gas flows along walls and filaments, penetrates within dark matter haloes and brings to the galaxies both angular momentum and fuel for star formation. Recent observational studies at low and intermediate redshifts have shown evidence that the cosmic web environment (e.g. proximity to cosmic filaments, or number of filaments connected to the galaxies sitting at the “nodes”) modulates galaxy mass assembly and morphology beyond the mere effect of halo mass and local density.