کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
8193762 | 1528887 | 2010 | 4 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
An expanding locally anisotropic (ELA) metric describing matter in an expanding universe
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
فیزیک و نجوم
فیزیک هسته ای و انرژی بالا
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![عکس صفحه اول مقاله: An expanding locally anisotropic (ELA) metric describing matter in an expanding universe An expanding locally anisotropic (ELA) metric describing matter in an expanding universe](/preview/png/8193762.png)
چکیده انگلیسی
It is suggested an expanding locally anisotropic metric (ELA) ansatz describing matter in a flat expanding universe which interpolates between the Schwarzschild (SC) metric near point-like central bodies of mass M and the Robertson-Walker (RW) metric for large radial coordinate:ds2=Zc2dt2â1Z(dr1âHr1cZα2+12cdt)2âr12dΩ, where Z=1âUSC with USC=2GM/(c2r1), G is the Newton constant, c is the speed of light, H=H(t)=aË/a is the time-dependent Hubble rate, dΩ=dθ2+sin2θdÏ2 is the solid angle element, a is the universe scale factor and we are employing the coordinates r1=ar, being r the radial coordinate for which the RW metric is diagonal. For constant exponent α=α0=0 it is retrieved the isotropic McVittie (McV) metric and for α=α0=1 it is retrieved the locally anisotropic Cosmological-Schwarzschild (SCS) metric, both already discussed in the literature. However it is shown that only for constant exponent α=α0>1 exists an event horizon at the SC radius r1=2GM/c2 and only for α=α0⩾3 space-time is singularity free for this value of the radius. These bounds exclude the previous existing metrics, for which the SC radius is a naked extended singularity. In addition it is shown that for α=α0>5 space-time is approximately Ricci flat in a neighborhood of the event horizon such that the SC metric is a good approximation in this neighborhood. It is further shown that to strictly maintain the SC mass-pole at the origin r1=0 without the presence of more severe singularities it is required a radial coordinate-dependent correction to the exponent α(r1)=α0+α12GM/(c2r1) with a negative coefficient α1<0. The energy-momentum density, pressures and equation of state are discussed.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Physics Letters B - Volume 684, Issues 2â3, 8 February 2010, Pages 73-76
Journal: Physics Letters B - Volume 684, Issues 2â3, 8 February 2010, Pages 73-76
نویسندگان
P. Castelo Ferreira,