Seminarium Zakładu Astrofizyki

Role of gas fraction and star formation efficiency in galaxy quenching

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.

3D view on Cosmic Baryon cycle

Galaxies are constantly fed by the diffuse material from the intergalactic medium through the Circum-Galactic Medium (CGM).We can probe these vast gaseous halos around galaxies by studying absorbers detected in the spectra of bright background quasars. To understand the dynamics of the system we combine the physical properties from the absorption features with the broader view of the absorber’s host and its environment by emission diagnostics, using IFU spectroscopy.

2019 Nobel prize in Physics: Cosmology

Half of this year Nobel prize in physics was awarded to Prof. Jim Peebles (IAS Princeton) "for contributions to our understanding of the evolution of the universe and Earth's place in the cosmos". The particular emphasis for the Prof. Peebles' half of the prize was: "or theoretical discoveries in physical cosmology". In my talk I shall describe and discuss seminal contributions to the field made by Jim Peebles over the years of his career.

Beyond broad lines - understanding spectra of quasars

The most prominent spectral features of quasars, as observed in optics and UV, are broad emission lines. Over development of knowledge importance of those features has increased. Recently, spectral
variability became useful in the field of cosmology. We still need deeper understanding of physics behind emitting spectra to improve quality of the measurements. I am going to present concepts used in the interpretation of the optical/UV observations and models/simulations aimed at reproducing spectra. I will briefly put proposed scenarios in the context of evolution.

Chemical compositions as indicators of evolution in binary systems. Results from studies of symbiotic giants

Symbiotic stars are a group of evolved, long-period binary systems composed of a cool giant donor and a hot, compact object - usually a white dwarf. The complex nature of interactions between the components of these systems makes them ideal for studying evolution in binary systems, especially at the final stages. Chemical composition, next to initial mass is among the major parameters determining stellar evolution. Until recently, knowledge of abundances in symbiotic red giants was limited to only a few cases.

Open charm measurement with a new silicon vertex detector for the NA61/SHINE experiment at the CERN SPS

The study of open charm meson production is an efficient tool for detailed investigations of the properties of hot and dense matter formed in nucleus-nucleus collisions. In particular, charm mesons are of vivid interest in the context of the phase-transition between confined hadronic matter and the quark-gluon plasma. Recently, the NA61/SHINE experiment was supplemented with a Small-Acceptance Vertex Detector (SAVD), motivated by the importance and the possibility of a first direct measurements of open charm mesons in heavy ion collisions at SPS energies.