RT info:eu-repo/semantics/masterThesis
T1 Development of a numerical model for star formation at low resolution
A1 Massaro Achá, Alex
AB The present Master’s thesis is concerned with the development and assessment of a prescription to model star formation in the low numerical resolution regime of cosmologicalhydrodynamical simulations.A study is made of previously introduced prescriptions in order to understand theirphysical motivations and to identify the features that cause them to produce different outcomes when changes to numerical resolution are made. It is found that these prescriptionsare based on a combination of theoretical and observational findings related to the multiphase nature of the interstellar medium, and the conditions under which a cloud becomesgravitationally unstable upon a phase transition from atomic to molecular composition.Additionally, empirical correlations in the form of star formation laws obligate these prescriptions to rely on local hydrodynamical properties of the cosmic gas in order to formstars in the simulations. This reliance unavoidably renders them resolution-dependent. Ingeneral, whenever a prescription to model unresolved physical processes in a cosmologicalhydrodynamical simulation makes use of local hydrodynamical properties, it is expectedthat its outcomes will be different for different numerical resolutions.On the basis of this difficulty, a new prescription has to be sought whenever a cosmological hydrodynamical simulation is intended to be run with an unprecedented numericalresolution, regardless of whether it is to the high or low end. For instance, simulationsthat aim to sample a larger volume of the Universe, in comparison with what its typicallydone, must adjust their numerical resolution to the low end in order to keep computational demands manageable. Hence, they require a prescription for star formation that iswell-behaved in this regime.Different procedures to arrive at such a prescription were taken into account, whichled to different alternatives being devised. Considering that this is a subject that has beenscarcely studied previously in the literature, attention is focused on the alternative thatcan provide the simplest recipe. Accordingly, a procedure is used that enables a connectionto be established between simulations of different numerical resolutions, through which anumber of insights can be gained about unresolved properties in low resolution simulations;in a statistical sense, evidently. This properties can then be used to form stars in saidsimulations.Having selected the simplest alternative, it was implemented in the public version of theArepo code for cosmological hydrodynamical simulations, and a series of simulations wererun in order to assess the degree to which this alternative is able to overcome the difficultiesof previously developed prescriptions. The results found certainly look promising; however,more in-depth studies are required to complement the assessment in regimes where thecurrent work is inadequate
YR 2020
FD 2020
LK http://riull.ull.es/xmlui/handle/915/19505
UL http://riull.ull.es/xmlui/handle/915/19505
LA en
NO Máster Universitario en Astrofísica
DS Repositorio institucional de la Universidad de La Laguna
RD 21-dic-2024