بررسی رمبش گرانشی غیر-تکین در نظریه راستال تعمیم یافته

ضیائی, امیر هادی

doi:10.22055/jrmbs.2020.15931

بررسی رمبش گرانشی غیر-تکین در نظریه راستال تعمیم یافته

نوع مقاله : مقاله پژوهشی کامل

نویسنده

امیر هادی ضیائی

گروه پژوهشی نجوم و اخترفیزیک نظری و تجربی، مرکز تحقیقات نجوم و اخترفیزیک، دانشگاه مراغه، مراغه، ایران

10.22055/jrmbs.2020.15931

چکیده

در این مقاله، به بررسی فرایند رمبش گرانشی یک سیال غبار-گونه همگن در نظریه گرانشی راستال تعمیم یافته می پردازیم. در این نظریه پارمتر جفت شدگی راستال متغیر است و از آنجاییکه این پارامتر نماینده میزان برهمکنش دوطرفه بین ماده و هندسه است، لذا انتظار می رود که یک چنین برهمکنش متغیری در دینامیک رمبش و محصول نهایی آن تاثیرگذار باشد. با الهام گرفتن از این ایده، به دنبال حلهای رمبش غیر-تکین برای فضازمان داخلی یک غبار در حال رمبش می گردیم. مشاهده می کنیم که انتخاب مناسبی از تابعیت پارامتر جفت شدگی، این امکان را فراهم می سازد بطوریکه تکینگی فضازمانی حاضر در مدل رمبش غبار همگن با یک جهش غیر تکین که در آن چگالی انرژی و انحنای فضازمان متناهی است جایگزین می گردد. همچنین مشاهده می شود که اثرات این جفت شدگی متغیر روی دینامیک افق ظاهری تاثیر دارد به گونه ای که برخلاف حالت تکین که در آن افق ظاهری تکینگی فضازمانی را می پوشاند، در حالت غیر-تکین تشکیل افق ظاهری به تاخیر افتاده و یا اینکه تشکیل نمی گردد و بنابراین امکان مشاهده توده درحال جهش توسط ناظر های خارجی وجود دارد.

کلیدواژه‌ها

موضوعات

گرانش و کیهانشناسی

عنوان مقاله [English]

Non-Singular gravitational collapse in generalized Rastall theory

نویسنده [English]

Amir Hadi Ziaie

Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), University of Maragheh, P.O. Box 55136-553, Maragheh, Iran

چکیده [English]

In the present work we study the process of gravitational collapse of a homogeneous dust in the framework of generalized Rastall gravity. In this theory, the Rastall coupling parameter is a variable and since this parameter represents the measure of mutual interaction between matter and geometry it is expected that such an interaction affects the collapse dynamics and its end product. Motivated by this idea, we search for non-singular solutions for the interior spacetime of the collapsing dust fluid. We observe that this scenario is feasible for a suitable choice of the functionality of the coupling parameter such that the singularity present in homogeneous dust collapse is replaced by a non-singular bounce where the energy density and spacetime curvature are finite. We also observe that such a variable coupling affects the dynamics of apparent horizon so that, in comparison to the singular case where the apparent horizon covers the spacetime singularity, the apparent horizon can be delayed or failed to form providing thus the possibility of detecting the bouncing object by external observers.

کلیدواژه‌ها [English]

Gravitational collapse
Spacetime singularity
Singularity avoidance
Modified gravity

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