Global ETD Search

1	The Effect of Cosmic Web Filaments on Quenching in Galaxy Clusters Kotecha, Sachin January 2020 (has links) Environment plays an important role in the evolution of galaxies. In particular, denser environments, such as galaxy clusters and large-scale field filaments of the cosmic web have been found to reduce star formation in galaxies. The intersection of these environments provides an interesting regime of study. We investigate how cosmic filaments impact the quenching of galaxies within one virial radius of 324 simulated clusters. We use hydrodynamic runs from The Three Hundred Project along with the cosmic web extractor DisPerSE to track filaments and the structure finder VELOCIraptor to identify halos hosting galaxies. Limited by the resolution of the simulation, we examine star formation indirectly by way of galaxy colour and cold gas fraction. We find that cluster galaxies residing closer to filaments tend to be star-forming, bluer, and contain more cold gas than their counterparts further away from filaments. This is in stark contrast with galaxies residing outside of clusters, where galaxies close to filaments show clear signs of density related pre-processing. Careful examination of flows around and into cluster galaxies strongly suggests that the colder, dynamically coherent hydrodynamic streams along intra-cluster filaments partially shield galaxies close to them from strangulation by the hot, dense intra-cluster medium. These streams, in addition to the reduced density contrast of intra-cluster filaments with the intra-cluster medium, also limit the ram pressure stripping experienced by cluster galaxies. We further examine stripping in the context of gas disturbances in phase space to create a classification for wet and dry galaxies. / Thesis / Master of Science (MSc) galaxy quenching astrophysics cosmology cosmic web filament
2	Void Evolution and Cosmic Star Formation Wasserman, Joel January 2023 (has links) The rate at which stars have formed throughout the history of theuniverse is not constant, it started out slow, increased until around redshift ∼ 2 when it reversed and became slower again. The reason for this behaviour is still being investigated with various models and simulations usually based upon dark matter halos. The aim of this study is to instead investigate whether there is a correlation between the cosmic star formation rate and the evolution of cosmic voids. This is achieved by comparing the total mass flow from voids with the amount of matter forming stars. A simple model of void mass flow is created and compared with observational data of star formation. The model is shown to exhibit the same behaviour as the star formation rate indicating that there is indeed a correlation between void evolution and star formation. This suggests it to be fruitful to create a more involved, alternative model of star formation based upon void evolution as opposed to the common halo evolution / Hur snabbt stjärnor bildas har genom universums historia förändrats över tid, det började långsamt och ökade sedan fram till rödförskutning ∼ 2 då trenden vände och saktade ner igen. Förklaringen till detta beteende utforskas fortfarande genom diverse modeller och simularingar som vanligtvis bygger på mörk materia halos. Syftet med detta arbete är att istället undersöka ifall det finns en korrelation mellan tomrumsutveckling och den kosmiska stjärnbildningen. Detta åstadkoms genom att jämföra det totala massflödet från tomrum med den massa som bildar stjärnorna. En simpel model för tomrumsutveckling skapas och jämförs med observationell data för stjärnbildningshastighet. Denna modell visar samma beteende som stjärnbildningen och tyder på att det finns en korrelation mellan denna och tommrumsutveckling. Som slutsats pekar denna studie på att det kan vara fruktbart att utveckla en mer anancerad modell för den kosmiska stjärnbildningen som bygger på tomrumsutveckling istället för mörk materia halos. Void Void Evolution Cosmic Void Star Formation Rate Star Formation History Cosmic Star Formation Cosmology Spherical Evolution Model SvdW Vdn Excursion Set Theory Excursion Set Formalism Astrophysics Astronomy Cosmic Web Matter Transfer Tomrum Tomrumsutveckling Kosmiska Tomrum Stjärnbildningshastighet Stjärnbildningshistorik Kosmisk stjärnbildning Kosmologi Sfärisk Evolutionsmodell SvdW Vdn Exkursionsset teori Exkursionsset Formalism Astrofysik Astronomi Kosmiska Spindelnätet Masstransport Astronomy, Astrophysics and Cosmology Astronomi, astrofysik och kosmologi

Search results

The Effect of Cosmic Web Filaments on Quenching in Galaxy Clusters

Void Evolution and Cosmic Star Formation