Browsing by Author "Tekola, Abiy G"
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- ItemOpen AccessOn the evolution of star forming galaxies : the metallicity of dwarfs and the effect of environment on local luminous IR galaxies(2011) Tekola, Abiy G; Väisänen, PetriThis thesis, entitled "On evolution of star forming galaxies: the metallicity of dwarfs and the effect of environment on local luminous infrared galaxies" is divided into two main areas. First a detailed study of the environment and star formation relationship of local Luminous Infrared Galaxies (LIRGs), with infrared (IR) luminosity (LIR) between 1011L and 1011L, where L is solar luminosity was carried out. Secondly, a chemical abundance analysis was done on three Local Volume dwarf irregular galaxies. In the first part, various redshift surveys were used to quantify the environment around LIRGs. It was found that LIR 1011L is a remarkable luminosity point among IR galaxies.
- ItemOpen AccessSpherically symmetric dark energy structures in the context of Chaplygin gas model(2006) Tekola, Abiy G; Tupper, Gary B; Viollier, Raoul DThis paper investigates the existence of spherically symmetrical dark energy structures under the context of Chaplygin gas. A scaling solution of the form r -2/3 is found for the density and then we calculated the corresponding rotational curve and it turns out to be unrealistic implying that such objects don't exist. Finally we modified the equation of state of the Chaplygin gas to an equation of state of the form P = (j 2 P - A and compared p with observational data to see to what physical extent this equation works and it isdetermined that it works as far as a couple of hundred Mpc while the physical length of galaxies is in Kpc. implying the modified Chaplygin equation fits the observed rotational curves.