Presentasjon av masteroppgave: Øyvind Brynhildsvoll Svendsen

Modelling uncertainty of the Rhenium-Osmium cosmic clock

Abstract

The nuclide  \( _{75} ^{187}Re\)  β‾ -decays to  \( _{76} ^{187}Os\)  with a half-life of approximately 41.6 Gyr. The long half-life and simple relation between  \( _{75} ^{187}Re\)  and  \( _{76} ^{187}Os\)  makes the ratio a good candidate for a cosmic clock. In order to "use the clock" we must determine the production of  \( _{75} ^{187}Re\)  and  \( _{76} ^{187}Os\)  through chemical enrichment of the Galaxy. This is a complicated task with a large number of assumptions and simplifications involved. The uncertainties related to some of the uncertainties are investigated.

A hydrodynamical simulation is approximated with a simple one-zone chemical evolution model. The physical parameters of the chemical evolution model is varied by generating random numbers with a Gaussian distribution to emulate the uncertainty of parameters.

I conclude that observational constraints on r-process nuclei does not affect the cosmochronology of the Re-Os system much. The Galactic history, like star formation and mass function over time, would have greater effect on the cosmochronology.

 

Veileder: Førsteamanuensis Sijing Shen, Institutt for teoretisk astrofysikk, UiO

Medveileder: Postdoktor Signe Riemer-Sørensen, Institutt for teroretisk astrofysikk, UiO

Intern sensor: Professor Øystein Elgarøy, Institutt for teoretisk astrofysikk, UiO

Ekstern sensor: Associate Professor, Christa Gall, Dark Cosmology Centre, University of Copenhagen.

Publisert 5. juni 2018 14:15 - Sist endret 5. juni 2018 14:15