|
|
|
题名
|
作者
|
年代
|
出处
|
被引量
|
| 1 | Bianchi Type-Ⅲ String Cosmological Models with Time Dependent Bulk Viscosity显示文摘 | BALI Raj PRADHAN Anirudh | 2007 | Chinese Physics Letters2007，24，2： | 1 |
| 2 | Some Magnetized Bulk Viscous String Cosmological Models in Cylindrically Symmetric Inhomogeneous Universe with Variable Λ-Term显示文摘某圆柱体的联盟者对称不同类粘滞液体绳有磁场并且宇宙论的术语 Λ
与时间变化的宇宙论的模型被调查。得到确定的解决方案,在模型的扩大(θ
) 与 shear 张肌 σ
11 成正比,这被假定 > j i 。为模型的宇宙论的常数的价值被发现小、积极,它被结果从最近的 supernovae Ia 观察支持。体积粘性的效果是在答案的特性上的完美的液体和因此展览必需品影响生产一个变化。模型的物理、几何的性质也在磁场的存在和缺席被讨论。 | Anirudh Pradhan | 2009 | Communications in Theoretical Physics2009，51，2： | 1 |
| 3 | Anisotropic Bianchi Type-I Magnetized String Cosmological Models with Decaying Vacuum Energy Density A(t)显示文摘The present study deals with a spatially homogeneous and anisotropic Bianchi-Ⅰ cosmological modelsrepresenting massive strings with magnetic field and decaying vacuum energy density A.The energy-momentum tensor,as formulated by Letelier(1983),has been used to construct massive string cosmological models for which we assume theexpansion scalar in the models is proportional to one of the components of shear tensor.The Einstein’s field equationshave been solved by applying a variation law for generalized Hubble’s parameter in Bianchi-Ⅰ space-time.The variationlaw for Hubble’s parameter generates two types of solutions for the average scale factor,one is of power-law type andother is of the exponential form.Using these two forms,Einstein’s field equations are solved separately that correspondto expanding singular and non-singular models of the universe respectively.We have made a comparative study ofaccelerating and decelerating models in the presence of string scenario.The study reveals that massive strings dominatein the decelerating universe whereas strings dominate in the accelerating universe.The strings eventually disappear fromthe universe for sufficiently large times,which is in agreement with current astronomical observations.The cosmologicalconstant A is found to be a positive decreasing function of time which is corroborated by results from recent supernovaela observations.The physical and geometric properties of the models have been also discussed in detail. | Anirudh Pradhan | 2011 | Communications in Theoretical Physics2011，55，5： | 0 |
| 4 | An Interacting Two-Fluid Scenario for Dark Energy in an FRW Universe显示文摘We study the evolution of the dark energy parameter within the scope of a spatially homogeneous and isotropic Friedmann-Robertson-Walker(FRW)model filled with barotropic fluid and dark energy.To obtain the deterministic solution we choose the scale factor a(t)=(√te^(t)),which yields a time-dependent deceleration parameter(DP).In doing so,we consider the case minimally coupled with dark energy to the perfect fluid as well as direct interaction with it. | Hassan Amirhashchi Anirudh Pradhan Bijan Saha | 2011 | Chinese Physics Letters2011，28，3： | 0 |
| 5 | Bianchi .Type-I Massive String Magnetized Barotropic Perfect Fluid Cosmological Model in General Relativity显示文摘Bianchi 类型 -- 我有通过这些技术的磁场 ofbarotropic 完成式液体分发的宇宙论的模型使用了由的巨大的绳更最近并且 Stachel 被调查。获得宇宙的确定的模型,宇宙充满 barotropic 完成式液体分发,这被假定。磁场由于与无限的电的电导率沿着 X 轴生产的电流。模型的行为当面并且和另外的物理方面的磁场的缺席进一步被讨论。 | BALI Raj PAREEK Umesh Kumar PRADHAN Anirudh | 2007 | Chinese Physics Letters2007，24，8： | 0 |
| 6 | Inhomogeneous Bulk Viscous Fluid Universe with Electromagnetic Field and Variable A-Term显示文摘Cylindrically symmetric inhomogeneoas cosmological model for bulk viscous fluid distribution with electro-magnetic field is obtained.The source of the magnetic field is due to an electric current produced along the z-axis.F_(12) isthe non-vanishing component of electromagnetic field tensor.To get the deterministic solution,it has been assumed thatthe expansion θ in the model is proportional to the shear σ.The values of cosmological constant for these models arefound to be small and positive at late time,which are consistent with the results from recent supernovae Ia observations.Physical and geometric aspects of the models are also discussed in presence and absence of magnetic field. | Anirudh Pradhan Vandana Rai Kanti Jotania | 2008 | Communications in Theoretical Physics2008，50，7： | 0 |
| 7 | A Plane-Symmetric Inhomogeneous Cosmological Model of Perfect Fluid Distribution with Electromagnetic Field Ⅰ显示文摘有电磁的地的完美的液体分发的一个飞机对称的不同类的宇宙论的模型被获得。F12 是电磁的领域张肌的非消失的部件。得到一个确定的解决方案,我们假设免费的重力的域是 Petrov type-II 非退化。模型的一些物理、几何的性质也被讨论。 | Anirudh Pradhan Prashant KumarSingh Anil Kumar Yadav | 2010 | Communications in Theoretical Physics2010，，7： | 0 |
| 8 | Stability of LRS Bianchi type-I cosmological models in f(R,T)-gravity显示文摘This paper examines the stability of the transition from the early decelerating stage of the Universe to the recent accelerating stage for the perfect fluid cosmological locally rotationally symmetric(LRS) Bianchi-I model in f(R, T) theory. To determine the solution of field equations, the idea of a timevarying deceleration parameter(DP) which yields a scale factor, for which the Universe attains a phase transition scenario and is consistent with recent cosmological observations, is used. The time-dependent DP yields a scale factor a=exp■, where β and k are respectively arbitrary and integration constants. By using the recent cons_traints(H_0 _= 73.8, and q_0 =-0.54) from Type Ia Supernova(SN Ia) data in combination with Baryonic Acoustic Oscillations(BAO) and Cosmic Microwave Background(CMB) observations(Giostri et al.), we obtain the values of β = 0.0062 and k = 0.000016 for which we have derived a cosmological model from the early decelerated phase to the present accelerating phase. By applying_ other r_ecent constraints(H_0 = 73.8, q_0 =-0.73) from SNe Ia Union data(Cunha), we obtain the values of β = 0.0036 and k = 0.000084 for which we have derived a cosmological model in the accelerating phase only. We have compared both models with experimental data. The stability of the background solution has been examined also for the metric perturbations alongside the properties of future singularities in a Universe ruled by dark energy with phantom type fluid. We demonstrate the presence of a stable fixed point with a condition of state ω <-1 and numerically affirm this is really a late-time attractor in the ghost overwhelmed Universe. Some physical and geometric properties of the model are found and examined. | Umesh Kumar Sharma Rashid Zia Anirudh Pradhan Aroon Beesham | 2019 | Research in Astronomy and Astrophysics2019，19，4： | 0 |
| 9 | Massive String Cosmology in Bianchi Type Ⅲ Space-Time with Electromagnetic Field显示文摘Exact solution of Einstein's field equations is obtained for massive string cosmological model of Bianchi IIIspace-time using the technique given by Letelier (1983) in presence of perfect fluid and electromagnetic field.To get thedeterministic solution of the Geld equations the expansion θ in the model is considered as proportional to the eigen valueσ_2~2 of the shear tensor σ_i^j and also the fluid obeys the barotropic equation of state.It is observed that in early stage ofthe evolution of the universe string dominates over the particle whereas the universe is dominated by massive string atthe late time.It is also observed that the string phase of the universe disappears in our model because particle densitybecomes negative.Some physical and geometric properties of the model are also discussed. | Anirudh Pradhan Suman Lata H.Amirhashchi | 2010 | Communications in Theoretical Physics2010，，11： | 0 |
| 10 | Higher Dimensional Strange Quark Matter Coupled to the String Cloud with Electromagnetic Field Admitting One Parameter Group of Conformal Motion显示文摘我们与物质纳入了字符串云的奇怪的夸克在高度维的球状地对称的空间时间解决爱因斯坦的域方程,假定保角的运动的一个参数组。答案在 r = r0 在边界上与高度维的 Reissner-Nordstrommetric 匹配。答案的特征也在高度维的空间时间的框架被讨论。 | PRADHAN Anirudh KHADEKAR G.S. MISHRA Mukesh Kumar KUMBHARE Sarojt | 2007 | Chinese Physics Letters2007，24，10： | 0 |
| 11 | Charged quark stars in f(R,T)gravity显示文摘Recent advances in nuclear theory and new astrophysical observations have led to the need for specific theoretical models applicable to dense-matter physics phenomena.Quantum chromodynamics(QCD)predicts the existence of non-nucleonic degrees of freedom at high densities in neutron-star matter,such as quark matter.Within a confining quark matter model,which consists of homogeneous,neutral 3-flavor interacting quark matter with O(m_(s)^(4))corrections,we examine the structure of compact stars composed of a charged perfect fluid in the context of f(R,T)gravity.The system of differential equations describing the structure of charged compact stars has been derived and numerically solved for a gravity model with f(R,T)=R+2βT.For simplicity,we assumed that the charge density is proportional to the energy density,namely,ρ_(ch)=αρ.It is demonstrated that the matter-geometry coupling constant β and charge parameter α affect the total gravitational mass and the radius of the star. | Juan M.Z.Pretel Takol Tangphati Ayan Banerjee Anirudh Pradhan | 2022 | Chinese Physics C2022，46，11： | 0 |
| 12 | Interacting two-fluid viscous dark energy models in a non-flat universe显示文摘We study the evolution of the dark energy parameter within the scope of a spatially non-flat and isotropic Friedmann-Robertson-Walker model filled with barotropic fluid and bulk viscous stresses.We have obtained cosmological solutions that do not have a Big Rip singularity,and concluded that in both non-interacting and interacting cases the non-flat open Universe crosses the phantom region.We find that during the evolution of the Universe,the equation of state for dark energy ωD changes from ωDeff>-1 to ωDeff<-1,which is consistent with recent observations. | Hassan Amirhashchi Anirudh Pradhan Hishamuddin Zainuddin | 2013 | Research in Astronomy and Astrophysics2013，13，2： | 0 |
| 13 | Accelerating dark energy models with anisotropic fluid in Bianchi type Ⅵ_0 space-time显示文摘Motivated by the increasing evidence for the need of a geometry that resembles Bianchi morphology to explain the observed anisotropy in the WMAP data,we have discussed some features of Bianchi type Ⅵ0 universes in the presence of a fluid that has an anisotropic equation of state(EoS) parameter in general relativity.We present two accelerating dark energy(DE) models with an anisotropic fluid in Bianchi type Ⅵ0 space-time.To ensure a deterministic solution,we choose the scale factor a(t)=2~tnet,which yields a time-dependent deceleration parameter,representing a class of models which generate a transition of the universe from the early decelerating phase to the recent accelerating phase.Under suitable conditions,the anisotropic models approach an isotropic scenario.The EoS for DE ω is found to be time-dependent and its existing range for derived models is in good agreement with data from recent observations of type Ia supernovae(SNe Ia)(Knop et al.2003),SNe Ia data combined with cosmic microwave background(CMB) anisotropy and galaxy clustering statistics(Tegmark et al.2004a),as well as the latest combination of cosmological datasets coming from CMB anisotropies,luminosity distances of high redshift SNe Ia and galaxy clustering.For different values of n,we can generate a class of physically viable DE models.The cosmological constant Λ is found to be a positive decreasing function of time and it approaches a small positive value at late time(i.e.the present epoch),which is corroborated by results from recent SN Ia observations.We also observe that our solutions are stable.The physical and geometric aspects of both models are also discussed in detail. | Anirudh Pradhan | 2013 | Research in Astronomy and Astrophysics2013，13，2： | 0 |
| 14 | Thick Domain Walls in Lyra Geometry with Bulk Viscosity显示文摘在这篇论文,我们在体积的存在在天琴座几何学为飞机对称的厚领域墙评估一般答案粘滞液体。为精力密度和域墙的压力的表达式在制服和时间变化排水量域 β
的两个盒子中被导出。模型的一些物理后果也被给。最后,测试粒子的测地学的方程和加速被讨论。 | Anirudh Pradhan | 2009 | Communications in Theoretical Physics2009，51，2： | 0 |
您所在的机构暂未开通此部分的功能，请联系管理员