Seminarium Zakładu Astrofizyki

Neutron stars are very complicated to study due to the extreme conditions occurring there. Mean densities are comparable to the atomic density. The magnetic fields strength on the surface ranges from 104 up to 1011 Tesla. Gravity is strong enough that it acts as a gravitational lens and bends the radiation emitted by the neutron star that the areas normally invisible become visible. The interaction between matter and radiation is very complicated. We must consider scattering processes, absorption, emission and illumination.

Currently ongoing observing run O3 (1st April 2019 - 30th April 2020) of three interferometric detectors (LIGO Livingston and Hanford, Virgo) surveys the largest volume of the Universe till date, and has already delivered more than 40 significant signal candidates. Here I will discuss the current status of the detectors, talk about the interesting signal cases (in particular the recently published GW190425), as well as plans for the future.

In the standard cosmological model (ΛCDM) baryonic components of galaxies, in form of stars, gas and dust, are thought to be embedded inside the dark matter (DM) haloes. This dark matter component is dominant and as such drives the evolution of the large-scale structure of the Universe.

Unfortunately, as for now, we can't directly observe dark matter, and we have to relay on models/simulations describing dark matter halo shapes and distribution. These models are based upon assumptions and some of them are known to be oversimplified.

Understanding the physics behind galaxy transition to quiescence is one of the most important questions in the field of galaxy formation and evolution. In order to differentiate between different proposed mechanisms, we use an indirect method to estimate gas masses for 61,000 SDSS DR7 galaxies. To achieve this, we infer gas column densities from dust mass densities as traced by extinction, applying a metallicity correction to account for varying dust-to-metal ratios.