Please use this identifier to cite or link to this item: https://hdl.handle.net/11147/5711
Title: Studies on modified Newtonian dynamics and dark matter
Other Titles: Modifiye Newton dinamiği ve karanlık madde üzerine çalışmalar
Authors: Demir, Durmuş Ali
Karahan, Canan Nurhan
Keywords: Newtonian dynamics
Dark matter
Modified Newtonian Dynamics
Tensor-Vector-Scalar theory
Issue Date: Dec-2016
Publisher: Izmir Institute of Technology
Source: Karahan, C. N. (2016). Studies on Modified Newtonian Dynamics and Dark Matter. Unpublished doctoral dissertation, İzmir Institute of Technology, İzmir, Turkey
Abstract: The flat rotation curves of the galaxies are considered to be anomalous observations according to Newtonian dynamics. There are two dierent approaches to explain this challenge - Dark Matter (DM) and Modified Newtonian Dynamics (MOND). Both of them possess some failures as well as many successes. Beyond these failures, they have much more fundamental diculties such as the lack of any direct or indirect detection of proposed dark matter candidates and the lack of a full-fledged relativistic version of MOND theory. In this thesis, focus will be on these fundamental problems. First, the relativistic MOND theory will be studied. The first successful relativistic version is Tensor-Vector-Scalar (TeVeS) theory based on bimetric gravity. However, the addition of vector and scalar fields into the theory by hand is not much dierent than the addition of dark matter. In this study, TeVeS theory will be constructed in a more natural way. To do this, at first standard Einstein-Hilbert action will be extended by using non-Riemannian structures (torsion, non-metricity, etc.) from metric-ane formalism. It will then be shown that obtained extended theory of gravity could turn into a Tensor- Vector-Scalar theory via decomposition of ane connection as Levi-Civita connection and rank(1,2) tensorial structure composed of lower rank fundamental and composite fields such as vector and scalar fields. Subsequently, it will be continued with a study on the relativistic MOND theory, without requiring an action principle. In this study, energy momentum tensor part will be modified rather than the geometrical part of the Einstein field equations. This could be considered as the first dynamical approach to relativistic MOND in the literature. It will be shown that the modified field equations obtained via this dynamical approach can be reduced to true MONDian force in the non-relativistic limit in some astrophysical domains. This study can be also considered as an extension of Milgrom’s modified inertia approach to relativistic domain. Finally, a new phenomenological model- Higgsed Stueckelberg scenario - involving a hidden vector field with an accompanying scalar field ensuring the gauge invariance will be proposed. It will be shown that the contributions from the hidden fields could stabilize the Higgs boson mass at one-loop, where the set up can accommodate naturally a viable DM candidate.
Galaksilerin düz dönme eğrileri Newton dinamiğine göre beklenenden farklı bir gözlemdir. Bu aykırı gözlemi açıklamak için iki farklı yaklaşım bulunmaktadır: karanlık madde ve Modifiye Newton Dinamiği (MOND). İki yaklaşım da birçok başarılarının yanısıra bazı başarısızlıklara sahiptir. Bu başarısızlıkların ötesinde önerilen karanlık madde adaylarının doğrudan veya dolaylı olarak algılamanın olmaması ve MOND teorisinin tam teşekküllü bir relativistik versiyonunun yokluğu gibi daha temel sorunları vardır. Bu tezde, karanlık madde ve MOND teorisinin bu temel problemleri üzerine odaklanılmıştır. İlk olarak MOND teorisinin relativistik genellemesi çalışılmıştır. MOND teorisinin ilk öne sürülen başarılı relativistik versiyonu bimetrik gravitasyonuna dayanan Tensör-Vektör-Skaler (TeVeS) teorisidir. Fakat vektör ve skaler alanların teoriye el ile eklenmesi, karanlık madde eklemekten çok farklı değildir. Bu çalışmada, TeVeS teorisi daha doğal bir yol ile elde edilmiştir. Metrik-afin formalizasyonundan gelen Riemann uzayında bulunmayan yapılar vasıtasıyla Einstein-Hilbert eylemi genişletilmiştir. Bu genişletilmiş gravitasyon teorisinin afin bağlantısının Levi-Civita bağlantısı ve (vektör ve skaler gibi daha düşük ranklı temel ve bileşik alanlardan oluşan) rank(1,2) tensor yapısı şeklinde ayrıştırılması yoluyla bir tensör-vektör-skaler teorisine dönüştüğü gösterilmiştir.
Description: Full text release delayed at author's request until 2018.01.27
Thesis (Doctoral)--Izmir Institute of Technology, Physics, Izmir, 2016
Includes bibliographical references (leaves: 71-88)
Text in English; Abstract: Turkish and English
xi, 96 leaves
URI: http://hdl.handle.net/11147/5711
Appears in Collections:Phd Degree / Doktora

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