We study the isotropization process of Bianchi-I space-times in Horndeski theory with G_(3)(X,ϕ)≠0 and G_(5)=const/X.A global unidirectional electromagnetic field interacts with a scalar field according to the law f^...We study the isotropization process of Bianchi-I space-times in Horndeski theory with G_(3)(X,ϕ)≠0 and G_(5)=const/X.A global unidirectional electromagnetic field interacts with a scalar field according to the law f^(2)(φ)F_(μv)F^(μv).In Horndeski theory,the anisotropy can develop in different ways.The proposed reconstruction method allows us to build models with acceptable anisotropy behavior.To analyze space-time anisotropy,we use the relations a_(i)/a(i=1,2,3),where are metric functions,and a≡(a_(1)a_(2)a_(3))^(1/3).展开更多
Horndeski theory constitutes the most general model of scalar-tensor theories.It has attracted much attention in recent years in relation with black holes,celestial dynamics,stability analysis,etc.It is important to n...Horndeski theory constitutes the most general model of scalar-tensor theories.It has attracted much attention in recent years in relation with black holes,celestial dynamics,stability analysis,etc.It is important to note that,for certain subclasses of Horndeski models,one can obtain analytic solutions for the background fields.This facilitates the investigation of the corresponding stability problems in detail.In particular,we aim to determine the constraints to the model or theory under which the stability conditions can be satisfied.In this study,we focused on a subclass of Horndeski theory and a set of analytic background solutions.In addition,the odd-parity gravitational perturbation and 2nd-order Lagrangian were investigated.Through careful analysis,the instability was identified within the neighborhood of the event horizon.This allows exclusion of a specific geometry for the model.Such an instability is implanted in the structure of the corresponding Lagrangian and is not erased by simply adding numerical constraints on the coupling parameters.As a starting point of our research,the current study provides insights for further exploration of the Horndeski theory.展开更多
文摘We study the isotropization process of Bianchi-I space-times in Horndeski theory with G_(3)(X,ϕ)≠0 and G_(5)=const/X.A global unidirectional electromagnetic field interacts with a scalar field according to the law f^(2)(φ)F_(μv)F^(μv).In Horndeski theory,the anisotropy can develop in different ways.The proposed reconstruction method allows us to build models with acceptable anisotropy behavior.To analyze space-time anisotropy,we use the relations a_(i)/a(i=1,2,3),where are metric functions,and a≡(a_(1)a_(2)a_(3))^(1/3).
基金Supported in part by the National Key Research and Development Program of China(2020YFC2201503)the National Natural Science Foundation of China(12205254,12275238,11675143)+2 种基金the Natural Science Foundation of Zhejiang Province,China(LR21A050001,LY20A050002)the Fundamental Research Funds for the Provincial Universities of Zhejiang Province,China(RF-A2019015)the Science Foundation of China University of Petroleum,Beijing,China(2462024BJRC005)。
文摘Horndeski theory constitutes the most general model of scalar-tensor theories.It has attracted much attention in recent years in relation with black holes,celestial dynamics,stability analysis,etc.It is important to note that,for certain subclasses of Horndeski models,one can obtain analytic solutions for the background fields.This facilitates the investigation of the corresponding stability problems in detail.In particular,we aim to determine the constraints to the model or theory under which the stability conditions can be satisfied.In this study,we focused on a subclass of Horndeski theory and a set of analytic background solutions.In addition,the odd-parity gravitational perturbation and 2nd-order Lagrangian were investigated.Through careful analysis,the instability was identified within the neighborhood of the event horizon.This allows exclusion of a specific geometry for the model.Such an instability is implanted in the structure of the corresponding Lagrangian and is not erased by simply adding numerical constraints on the coupling parameters.As a starting point of our research,the current study provides insights for further exploration of the Horndeski theory.
