Chameleon Gravıty
Chameleon Gravıty
Dosyalar
Tarih
06.01.2013
Yazarlar
Boran, Sibel
Süreli Yayın başlığı
Süreli Yayın ISSN
Cilt Başlığı
Yayınevi
Fen Bilimleri Enstitüsü
Institute of Science and Technology
Institute of Science and Technology
Özet
Bu çalışmada, bilinen ivmelenerek genişleyen bugünkü evren modeline teorik olarak alternatif bir açıklama kazandırmak için, skaler–tensor teorilerden yardımla, vakum enerjisi kaynaklı quintessence skaler alan modelleri kullanılmıştır. Bu tür kosmolojik skaler alanlar yoğun bir ortamda bulunduğunda, eşdeğerlik ilkesinin yerel testlerinde henüz tespit edilmemiştir. Bu bağlamda, bu çalışmanın temelini oluşturan bukalemun kütle çekimi yerel madde yoğunluğuna bağlı olarak skaler alanın kütle kazanmasını anlatan yeni bir senaryo olarak literatürde ortaya çıkmıştır. Maddeye konformal olarak bağlanan bukalemun skaler alanının farklı yoğun ortamlardaki davranışları ve kosmolojik evrimi incelenmiştir. Tüm bunları yapabilmek için varyasyonel yöntemlerden faydalanılarak, skaler-tensor teori kaynaklı bukalemun skaler alan lagranjiyeninden hareket denklemleri eldesine gidilmiştir ve buradan potensiyele bağlı olarak elde edilen skaler alanın kütlesi hakkında yorumda bulunulmuştur. Son olarak, doğada bukalemun alanının varlığının somut kanıtı olarak yakın gelecekte gerçekleşecek olan uydu deneyleri hakkında bazı açıklamalar yapılmıştır.
In this study, the based vacuum energy scalar fields are used to provide theoretical alternative meaning to the known accelerated expanding present universe model with the help of scalar-tensor theory. These cosmological scalar fields have not yet been detected in local tests of the equivalence principle because we happen to live in a dense environment. In this context, being the subject of this thesis the chameleon gravity has come out as a novel scenario in the literature where a scalar field acquires a mass which depends on the local matter density. In the different density environments the behaviours of the conformally coupling chameleon scalar fields to matter and their cosmological evolution are examined. In order to able to do all of these, coming from scaler-tensor theory the equations of motion for the chameleon scalar field lagrangian are obtained by using the variational method and the discussion is made about the obtained scalar field mass as depending on potential. As final, some explanations have been made about the satellite experiments which will be in the near future to detect as concrete evidence of the existence of the chameleon scalar fields in the Nature.
In this study, the based vacuum energy scalar fields are used to provide theoretical alternative meaning to the known accelerated expanding present universe model with the help of scalar-tensor theory. These cosmological scalar fields have not yet been detected in local tests of the equivalence principle because we happen to live in a dense environment. In this context, being the subject of this thesis the chameleon gravity has come out as a novel scenario in the literature where a scalar field acquires a mass which depends on the local matter density. In the different density environments the behaviours of the conformally coupling chameleon scalar fields to matter and their cosmological evolution are examined. In order to able to do all of these, coming from scaler-tensor theory the equations of motion for the chameleon scalar field lagrangian are obtained by using the variational method and the discussion is made about the obtained scalar field mass as depending on potential. As final, some explanations have been made about the satellite experiments which will be in the near future to detect as concrete evidence of the existence of the chameleon scalar fields in the Nature.
Açıklama
Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2012
Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2012
Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2012
Anahtar kelimeler
Skaler-Tensor teori,
kozmolojik ivmelenme,
quintessence,
bukalemun skaler alan.,
Scalar-Tensor Theory,
cosmological acceleration,
quintessence,
chameleon scalar field.