Instability analysis of a cylindrical stellar object in Brans-Dicke gravity
Sharif M., Manzoor R.

Поступила в редакцию: 28 Сентября 2015

DOI: 10.7868/S0044451016050072

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This paper investigates instability ranges of a cylindrically symmetric collapsing cosmic filamentary structure in the Brans-Dicke theory of gravity. For this purpose, we use a perturbating approach to the modified field equations as well as dynamical equations and construct a collapse equation. The collapse equation with an adiabatic index (Γ ) is used to explore the instability ranges of both isotropic and anisotropic fluid in Newtonian and post-Newtonian approximations. It turns out that the instability ranges depend on the dynamical variables of collapsing filaments. We conclude that the system always remains unstable for 0<Γ <1, while Γ >1 provides instability only in a special case.