f(R,Φ,X) Teori'de İvmeli Genişleyen Kozmolojiler

Abstract

Bu çalışmada, evrenin başlangıç ve günümüz genişlemesi, f(R,Φ,X) gravite çerçevesinde gözden geçirilmiştir. İdeal akışkanlı Friedmann-Lemaître-Robertson-Walker uzay-zamanı için alan denklemleri ve çözümleri f(R,Φ,X)=f_0 R+f_1 X^q-V(Φ) modeli dikkate alınarak elde edilmiştir. Statik olmayan uzay-zaman geometrileri için f(R,Φ,X) gravite ve f(R,Φ,X)=f_0 R+f_1 X^q-V(Φ) modelinin geçerliliği basınç ve enerji yoğunluğu gibi elde edilen madde dinamikleri kullanılarak tartışılmıştır. Elde edilen sonuçlardan erken ve geç dönem genişlemeleri için f fonksiyonunun sabit değer aldığı görülmüştür. Bu durum f(R,Φ,X) fonksiyonunun Ricci skalerine birinci dereceden bağlı bir fonksiyon olduğunu göstermektedir. f(R,Φ,X)=f_0 R+f_1 X^q-V(Φ) modeli ile birlikte düşünüldüğünde Φ→0 ve X→0 limitinde elde edilen çözümlerin f(R) gravitenin Λ-CDM modeline indirgeneceği anlaşılmaktadır. Öyleki elde edilen çözümlerin beklenen durum ile uyuşum içinde olması teorinin tutarlı bir gravitasyon teorisi olduğunu desteklemektedir.

Keywords

• f(R Φ X) Gravite
• İdeal akışkan
• Friedmann- Lemaître-Robertson-Walker Uzay-Zamanı

Accelerately Expanding Cosmologies in f(R,Φ,X) Theory

Abstract

In this study, beginning and today expansion of universe are viewed in f(R,Φ,X) gravity. Field equations and their solutions of Friedmann-Lemaître-Robertson-Walker cosmologies with perfect fluid are obtained by considering f(R,Φ,X)=f_0 R+f_1 X^q-V(Φ) model. Validity of both f(R,Φ,X) gravity and f(R,Φ,X)=f_0 R+f_1 X^q-V(Φ) model for non-static space-time geometries is discussed by making use of the obtained matter dynamics results such as pressure and energy density. It is seen that in all obtained solutions by taking into account early and late period expansion, f function is a constant. This indicates that f(R,Φ,X) function is a first-order dependent function of Ricci scalar. When f(R,Φ,X)=f_0 R+f_1 X^q-V(Φ) model is considered together, it is understood that the obtained solutions could be reduced to Λ-CDM model for f(R) gravity in limits of Φ→0 and X→0. The fact that the obtained results agree with expected situations supports. So, f(R,Φ,X) theory is a consistent theory of gravity.

Keywords

• f(R Φ X) Gravity
• Perfect Fluid
• Friedmann- Lemaître-Robertson-Walker Space-Time

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