نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشکده ریاضی، کالج کامروپ، چاماتا، آسام، هند
2 دانشکده ریاضی، دانشگاه مانیپور، ایمفال، مانیپور، هند
چکیده
در این مقاله با در نظر گرفتن گرانروی توده به عنوان (i) کمیت ثابت و (ii) توابع زمان کیهانی، معادلات میدان در مدل 5 بعدی بیانچی نوع I در چارچوب نظریۀ نسبیت عام، با استفاده از مفروضات فیزیکی معینی که در توافق با یافته‌های مشاهداتی حاضر هستند، به دست آمده و حل شده است. در هر دو مورد، این مدل، یک جهان در حال انبساط و شتاب‌دار نمایی را نشان می‌دهد که با حجم صفر شروع و با حجم بی‌نهایت متوقف می‌شود. مدل یک تکینگی اولیه دارد و در نهایت به فاز دی سیتر (q = −1) نزدیک می‌شود و همچنین شرایط انرژی "چگالی انرژی ≥0 و چگالی ذرات ≥0" را برآورده می‌کند. این مدل یک جهان غالبا مادی را نشان می‌دهد که با داده های رصدی فعلی موافق است. مدل حاضر ناهمسانگرد است و در سراسر تکامل خود برای n≠1 برشی است.
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
String Cosmological Model in 5-Dimensional Space-Time: Interacting with iscous Fluid
نویسندگان [English]
- Jiten Baro 1
- Kangujam Priyokumar Singh 2
1 Kamrup College, Chamata, Nalbari, India
2 2. Department of Mathematics, Manipur University, Imphal-795003, Manipur, India
چکیده [English]
Considering bulk viscosity as (i) constant quantity and (ii) functions of cosmic time, the field equations in 5-dimensional Bianchi type-I model in the context of general theory of relativity, has been obtained and solved in this paper by the use of certain physical assumptions, which are agreeing with the present observational findings. In both cases, the model represents an exponentially expanding and accelerating Universe that starts with volume 0 and stops with infinite volume. The model has an initial singularity and will eventually approach the de-Sitter phase ( ). It also satisfies the energy conditions and . This model represents a matter-dominated Universe that agrees with current observational data. The model is anisotropic one and shearing throughout its evolution for .
Considering bulk viscosity as (i) constant quantity and (ii) functions of cosmic time, the field equations in 5-dimensional Bianchi type-I model in the context of general theory of relativity, has been obtained and solved in this paper by the use of certain physical assumptions, which are agreeing with the present observational findings. In both cases, the model represents an exponentially expanding and accelerating Universe that starts with volume 0 and stops with infinite volume. The model has an initial singularity and will eventually approach the de-Sitter phase ( ). It also satisfies the energy conditions and . This model represents a matter-dominated Universe that agrees with current observational data. The model is anisotropic one and shearing throughout its evolution for .
کلیدواژه‌ها [English]
- 5 dimensions
- cloud strings
- viscous fluid
- bianchi type-I space-time
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