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Evolution of dwarf galaxies in the Fornax cluster

PhD ceremony:Mr A.P. (Aku) Venhola
When:March 29, 2019
Supervisors:prof. dr. R.F. (Reynier) Peletier, prof. dr. J.H.V. Salo
Co-supervisor:dr. E. Laurikainen
Where:Academy building RUG
Faculty:Science and Engineering
Evolution of dwarf galaxies in the Fornax cluster

In my thesis, I studied how the dense galaxy cluster environment affects the evolution of dwarf galaxies. For the analysis, I used the imaging data of the Fornax Deep Survey (FDS) that is a deep optical multi-band survey done in collaboration of Dutch and Italian groups using the VST telescope of the European Southern Observatory (ESO) located at Paranal, Chile. I used the deep images of the FDS to search for previously undetected faint dwarf galaxies in the Fornax cluster, and by analyzing their structure, morphology, and colors studied how the properties of the dwarf galaxies change from the outskirts of the cluster towards its center. We obtained new observational evidence suggesting that the star formation of the lowest mass galaxies (stellar mass < 10^8 solar mass) quickly stops in the cluster environment as the cold gas of the dwarf galaxies, that is the fuel of their star-formation, gets removed due to the interactions with the hot intra-cluster gas. More massive dwarfs than that are able to hold some of their cold gas bound, and thus continue forming stars longer in the cluster. Our analysis of the dwarf galaxies in the Fornax cluster is the most extensive work done in that galaxy environment, and it will work as a basis for follow-up studies. I also tested a new max-tree based algorithm to automatically identify faint galaxies from astronomical images and showed that it performs better than the current standard tool of the field.