Conserved Charges in Extended Theories of Gravity
Total Page:16
File Type:pdf, Size:1020Kb
Conserved Charges in Extended Theories of Gravity Hamed Adami∗ Department of Science, University of Kurdistan, Sanandaj, Iran Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), P.O. Box 55134-441, Maragha, Iran Mohammad Reza Setare† Department of Science, Campus of Bijar, University of Kurdistan, Bijar, Iran Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), P.O. Box 55134-441, Maragha, Iran Tahsin Çağrı Şişman‡ Department of Astronautical Engineering, University of Turkish Aeronautical Association, 06790 Ankara, Turkey Bayram Tekin§ Department of Physics, Middle East Technical University, 06800 Ankara, Turkey (Dated: September 13, 2019) We give a detailed review of construction of conserved quantities in extended theories of gravity for asymptotically maximally symmetric spacetimes and carry out explicit compu- tations for various solutions. Our construction is based on the Killing charge method, and a proper discussion of the conserved charges of extended gravity theories with this method requires studying the corresponding charges in Einstein’s theory with or without a cosmo- logical constant. Hence we study the ADM charges (in the asymptotically flat case but in generic viable coordinates), the AD charges (in generic Einstein spaces, including the anti-de Sitter spacetimes) and the ADT charges in anti-de Sitter spacetimes. We also discuss the conformal properties and the behavior of these charges under large gauge transformations as well as the linearization instability issue which explains the vanishing charge problem for some particular extended theories. We devote a long discussion to the quasi-local and off- shell generalization of conserved charges in the 2+1 dimensional Chern-Simons like theories and suggest their possible relevance to the entropy of black holes. Contents arXiv:1710.07252v3 [hep-th] 12 Sep 2019 I. Reading Guide and Conventions 4 I GLOBAL CONSERVED CHARGES II. Introduction 4 III. ADT Energy 6 A. AD and ADM Conserved Charges 9 B. Large diffeomorphisms (gauge transformations) 12 C. Schwarzschild-(A)dS Black Holes in n-dimensions 14 2 D. Kerr-AdS Black Holes in n-dimensions 14 E. Computation of the charges for the solitons 16 1. The AdS Soliton 16 2. Eguchi-Hanson Solitons 17 F. Energy of the Taub-NUT-Reissner-Nordstr¨om metric 17 IV. Charges of Quadratic Curvature Gravity 18 µν V. Charges of f Rρσ Gravity 21 A. Example 1: Charges of Born-Infeld Extension of New Massive Gravity (BINMG) 25 VI. Conserved Charges of Topologically Massive Gravity 26 1. Logarithmic solution of TMG at the chiral point 31 2. Null warped AdS3 32 3. Spacelike stretched black holes 32 VII. Charges in Scalar-Tensor Gravities 33 VIII. Conserved Charges in the First Order Formulation 33 IX. Vanishing Conserved Charges and Linearization Instability 35 II CONSERVED CHARGES FOR EXTENDED 3D GRAVITIES: QUASI-LOCAL APPROACH X. Introduction 38 XI. Chern-Simons-like theories of gravity 39 A. First order formalism of gravity theories 39 B. Lorentz-Lie derivative and total variation 42 C. Gravity in three dimensions 43 D. Chern-Simons-like theories of gravity as the general 45 XII. Some examples of Chern-Simons-like theories of gravity 46 A. Example.1: Einstein’s gravity with a negative cosmological constant 46 1. Banados-Teitelboim-Zanelli black hole 47 B. Example.2: Minimal Massive Gravity 47 C. Example.3: New Massive Gravity 48 1. Rotating Oliva-Tempo-Troncoso black hole as a solution of new massive gravity 49 D. Example.4: Generalized Massive Gravity 50 E. Example.5: Generalized Minimal Massive Gravity 50 1. Solutions of Einstein gravity with negative cosmological constant 51 2. Warped black holes 52 XIII. Extended off-shell ADT current 53 XIV. Off-shell extension of the covariant phase space method 56 XV. Quasi-local conserved charge 57 XVI. Black hole entropy in Chern-Simons-like theories of gravity 58 XVII. Asymptotically AdS3 spacetimes 61 A. Brown-Henneaux boundary conditions 61 B. General massive gravity 63 3 XVIII. Asymptotically spacelike warped anti-de Sitter spacetimes in General Minimal Massive Gravity 65 A. Asymptotically spacelike warped AdS3 spacetimes 65 B. Conserved charges of asymptotically spacelike warped AdS3 spacetimes in General Minimal Massive Gravity 67 C. The algebra of conserved charges 68 D. Mass, angular momentum and entropy of warped black hole solution of general minimal massive Gravity 70 XIX. Conserved charges of the Rotating Oliva-Tempo-Troncoso black hole 72 XX. Explicit examples of the black hole entropy 73 A. Banados-Teitelboim-Zanelli black hole entropy 73 1. Minimal Massive Gravity 74 2. General Massive Gravity 74 3. General Minimal Massive Gravity 74 B. Warped black hole entropy from the gravity side 75 C. Entropy of the rotating Oliva-Tempo-Troncoso black hole 75 XXI. Near horizon symmetries of the non-extremal black hole solutions of the General Minimal Massive Gravity 76 A. Near horizon symmetries of non-extremal black holes 77 B. Near horizon conserved charges and their algebra for General Minimal Massive Gravity 78 XXII. Extended near horizon geometry 80 A. Application to the general minimal massive gravity 81 B. Soft hair and the soft hairy black hole entropy 83 XXIII. Horizon Fluffs In Generalized Minimal Massive Gravity 84 A. "Asymptotic" and "near horizon" conserved charges and their algebras 85 1. Asymptotic conserved charges 85 2. Near horizon conserved charges 86 B. Relation between the asymptotic and near horizon algebras 86 XXIV. Asymptotically flat spacetimes in General Minimal Massive Gravity 87 A. Asymptotically 2+1 Dimensional Flat Spacetimes 87 B. Conserved charges of asymptotically flat spacetimes in general minimal massive gravity 89 C. Thermodynamics 91 XXV. Conserved Charges of Minimal Massive Gravity Coupled to Scalar Field 93 A. Minimal massive gravity coupled to a scalar field 93 B. Field equations 94 C. Quasi-local conserved charges 96 D. General formula for entropy of black holes in minimal massive gravity coupled to a scalar field 98 E. Application for the BTZ black hole with ϕ = ϕ0 99 F. Virasoro algebra and the central extension 100 XXVI. Conclusions 102 XXVII. Acknowledgments 102 A. EQCA and Linearization of the Field Equations 102 B. Procedure of obtaining equations (331)-(336) 108 C. Technical proof of equation (338) 109 4 References 109 I. READING GUIDE AND CONVENTIONS This review is naturally divided into two parts: In Part I, we discuss global conserved charges for generic modified or extended gravity theories. Global here refers to the fact that the integrals defining the charges are on a spacelike surface on the boundary of the space. In Part II, we discuss quasi-local and off-shell conserved charges; particularly, for 2+1 dimensional gravity theories with Chern-Simons like actions. In what follows, the meaning of these concepts will be elaborated. Here, let us briefly denote our conventions of the signature of the metric and the Riemann curvature: We use the mostly plus signature with g = diag(−, +, ..., +) and take the Riemann tensor to be defined as ρ ρ σ [∇µ, ∇ν] V = Rµν σV , (1) and the Ricci tensor is defined as ρ Rµν = R µρν, (2) while the scalar curvature is µ R = R µ. (3) Part I GLOBAL CONSERVED CHARGES II. INTRODUCTION The first “casualty of gravity” is Noether’s theorem [1], well at least for the case of rigid spacetime symmetries and their corresponding conserved charges. The “Equivalence Principle” in any form is both a blessing and a curse: it makes gravity locally trivial (essentially a coordinate effect in the extreme limit of going to a point-like lab) but then it also, for the same reason, makes it hard to find local observables in gravity. In fact all the observables must be global. To heuristically understand this, as an example, consider the energy momentum density of the gravitational field: Being a bosonic (spin-2) field, its kinetic energy density is expected to be of the form K ∼ ∂g∂g which makes no covariant sense as it can be set to zero in a locally inertial frame (or in Riemann normal coordinates). This state of affairs of course affects both the classical gravity and the would-be quantum gravity. The first thing one wants to know and compute in any theory are the “observables” and it turns out generically, a spacetime has no observables and it would not make sense to construct classical and quantum theories for those spacetimes. For example, in a ∗Electronic address: [email protected] †Electronic address: [email protected] ‡Electronic address: [email protected] §Electronic address: [email protected] 5 spacetime such as the de Sitter spacetime which does not have a global timelike Killing vector or an asymptotic spatial infinity, defining a global conserved positive energy is not possible [2]. In the absence of a tensorial quantity that can represent local gravitational energy-mass, mo- mentum etc, one necessarily resorts to new ideas; two of which are quasilocal expressions that try to capture gravitational quantities contained in a finite region of space or the global expressions that are assigned to the totality of spacetime. Both of these involve integrations over some regions of space, and they are not tensorial. But, that does not mean that they are physically irrelevant. On the contrary, they are designed to answer physical questions such as what is the mass of a black hole or how much energy is radiated if two black holes merge as in the recent observations by the LIGO detectors, of course with the assumption that these systems can be isolated from the rest of the Universe? Especially, global expressions that we shall discuss, the Arnowitt-Deser- Misner (ADM) [3] and the Abbott-Deser (AD) conserved charges [4], and their generalizations to higher derivative models the Abbott-Deser-Tekin (ADT) conserved charges [5, 6] are well-defined for asymptotically flat and anti-de Sitter spaces, given the proper decay conditions on the metric and the extrinsic curvature of the Cauchy surface.