Black holes and their horizons in semiclassical and modified theories of gravity

Abstract

For distant observers black holes are trapped spacetime domains bounded by apparent horizons. We review properties of the near-horizon geometry emphasizing the consequences of two common implicit assumptions of semiclassical physics. The first is a consequence of the cosmic censorship conjecture, namely that curvature scalars are finite at apparent horizons. The second is that horizons form in finite asymptotic time (i.e. according to distant observers), a property implicitly assumed in conventional descriptions of black hole formation and evaporation. Taking these as the only requirements within the semiclassical framework, we find that in spherical symmetry only two classes of dynamic solutions are admissible, both describing evaporating black holes and expanding white holes. We review their properties and present the implications. The null energy condition is violated in the vicinity of the outer horizon and satisfied in the vicinity of the inner apparent/anti-trapping horizon. Apparent and anti-trapping horizons are timelike surfaces of intermediately singular behavior, which manifests itself in negative energy density firewalls. These and other properties are also present in axially symmetric solutions. Different generalizations of surface gravity to dynamic spacetimes are discordant and do not match the semiclassical results. We conclude by discussing signatures of these models and implications for the identification of observed ultra-compact objects.

arXiv comment89 pages, 8 figures, 3 tables. Invited review published in International Journal of Modern Physics D (World Scientific). Fixed typo in the second term of Eq. (C.5). Comments welcome!

References in corpus (165)

• f(R) Theories Of Gravity
• The Confrontation between General Relativity and Experiment
• f(R) theories
• Extended Theories of Gravity
• Introduction to Modified Gravity and Gravitational Alternative for Dark Energy
• Thermodynamics of Spacetime: The Einstein Equation of State
• First M87 Event Horizon Telescope Results. IV. Imaging the Central Supermassive Black Hole
• Black Holes: Complementarity or Firewalls?
• Formation and evaporation of non-singular black holes
• The Stretched Horizon and Black Hole Complementarity
• The information paradox: A pedagogical introduction
• Testing the nature of dark compact objects: a status report
• Thermodynamical Aspects of Gravity: New insights
• Isolated and dynamical horizons and their applications
• Soft Hair on Black Holes
• The Thermodynamics of Black Holes
• Quantum Gravity in Everyday Life: General Relativity as an Effective Field Theory
• TOPICAL REVIEW: General relativistic boson stars
• Black holes, gravitational waves and fundamental physics: a roadmap
• General Laws of Black-Hole Dynamics
• The entropy of Hawking radiation
• Quantum Spacetime Phenomenology
• Quantum Information and Relativity Theory
• Unified first law of black-hole dynamics and relativistic thermodynamics
• Primordial Black Holes
• Gravity and the Thermodynamics of Horizons
• AdS/CFT duality and the black hole information paradox
• Stationary Black Holes: Uniqueness and Beyond
• Rotating regular black holes
• Jerusalem Lectures on Black Holes and Quantum Information
• Better Late than Never: Information Retrieval from Black Holes
• Hawking Radiation and Black Hole Thermodynamics
• The observational evidence for horizons: from echoes to precision gravitational-wave physics
• Notes on non-singular models of black holes
• Black-bounce to traversable wormhole
• Tests for the existence of horizons through gravitational wave echoes
• A Primer for Black Hole Quantum Physics
• Black hole evaporation: A paradigm
• Black Hole Remnants and the Information Loss Paradox
• General parametrization of axisymmetric black holes in metric theories of gravity
• Black hole boundaries
• Information Loss
• Spacetime Structure of an Evaporating Black Hole in Quantum Gravity
• The 1965 Penrose singularity theorem
• Recent developments in gravitational collapse and spacetime singularities
• Tunnelling Methods and Hawking's radiation: achievements and prospects
• No hair for spherical black holes: charged and nonminimally coupled scalar field with self--interaction
• Hawking radiation, the Stefan-Boltzmann law, and unitarization
• Energy conditions in general relativity and quantum field theory
• The Black Hole information problem: past, present, and future
• Primordial Black Holes Confront LIGO/Virgo data: Current situation
• Information loss problem and a `black hole' model with a closed apparent horizon
• On the viability of regular black holes
• Geodesically complete black holes
• Einstein's equations as a thermodynamic identity: The cases of stationary axisymmetric horizons and evolving spherically symmetric horizons
• Observation of Incipient Black Holes and the Information Loss Problem
• Production and decay of evolving horizons
• Not quite a black hole
• Classifying and avoiding singularities in the alternative gravity dark energy models
• Classical collapse to black holes and quantum bounces: A review
• A model for non-singular black hole collapse and evaporation
• Minimal conditions for the existence of a Hawking-like flux
• Kodama time: Geometrically preferred foliations of spherically symmetric spacetimes
• Harvesting Entanglement from the Black Hole Vacuum
• Probing Fundamental Physics with Gravitational Waves: The Next Generation
• Black holes have no short hair
• Dynamical surface gravity
• Gravitational vacuum polarization I: Energy conditions in the Hartle--Hawking vacuum
• Gravitational vacuum polarization IV: Energy conditions in the Unruh vacuum
• A Self-consistent Model of the Black Hole Evaporation
• Inner horizon instability and the unstable cores of regular black holes
• Physical observability of horizons
• Quantum radiation from an evaporating non-singular black hole
• Vaidya spacetimes, black-bounces, and traversable wormholes
• Hawking radiation, Unruh radiation and the equivalence principle
• Exercices de style: a homotopy theory for set theory, I
• Upper bound on the radii of black-hole photonspheres
• The Many Definitions of a Black Hole
• Regular black holes with stable cores
• PBH formation from spherically symmetric hydrodynamical perturbations: a review
• Opening the Pandora's box at the core of black holes
• The region with trapped surfaces in spherical symmetry, its core, and their boundaries
• Versatile method for renormalized stress-energy computation in black-hole spacetimes
• Black Hole evaporation: A Perspective from Loop Quantum Gravity
• Stellar equilibrium in semiclassical gravity
• Harvesting correlations in Schwarzschild and collapsing shell spacetimes
• Static detectors and circular-geodesic detectors on the Schwarzschild black hole
• Light Rays, Singularities, and All That
• The physics of the relativistic counter-streaming instability that drives mass inflation inside black holes
• Foliation dependence of black hole apparent horizons in spherical symmetry
• Low Energy Theorems of Quantum Gravity from Effective Field Theory
• Renormalized stress-energy tensor of an evaporating spinning black hole
• Surface gravities for non-Killing horizons
• On Reflectivity of Quantum Black Hole Horizons
• Astronomical tests for quantum black hole structure
• Trapped surfaces
• Unruh-DeWitt detector response along static and circular geodesic trajectories for Schwarzschild-AdS black holes
• Quasi-particle creation by analogue black holes
• Fuzzy Dark Matter and the 21cm Power Spectrum
• Pure states don't wear black
• Spacetime Singularities
• Quantum fluxes at the inner horizon of a spherical charged black hole
• Hawking radiation as perceived by different observers
• Some aspects of field equations in generalised theories of gravity
• Radiation from collapsing shells, semiclassical backreaction and black hole formation
• Renormalized stress-energy tensor for stationary black holes
• Mass Inflation in the Loop Black Hole
• Higher-order theories of gravity: diagnosis, extraction and reformulation via non-metric extra degrees of freedom
• Phenomenological Description of the Interior of the Schwarzschild Black Hole
• Role of evaporation in gravitational collapse
• Modified gravity without dark matter
• Geometric Horizons
• Resisting collapse: How matter inside a black hole can withstand gravity
• Identification of black hole horizons using scalar curvature invariants
• Quantum inequality in spacetimes with small curvature
• Pre-Hawking radiation cannot prevent the formation of apparent horizon
• Black hole quantum atmosphere for freely falling observers
• Quantum fields during black hole formation: How good an approximation is the Unruh state?
• Obstruction of black hole singularity by quantum field theory effects
• Stability and gravitational collapse of neutron stars with realistic equations of state
• Black hole evaporation and semiclassical thin shell collapse
• Energy-momentum tensor and metric near the Schwarzschild sphere
• What Happens to Apparent Horizons in a Binary Black Hole Merger?
• Not quite black holes at LIGO
• Closed trapping horizons without singularity
• Temperature and entropy-area relation of quantum matter near spherically symmetric outer trapping horizons
• Hawking-Ellis classification of stress-energy: test-fields versus back-reaction
• Ingoing Eddington-Finkelstein Metric of an Evaporating Black Hole
• Anatomy of a thermal black hole mimicker
• Singularities, black holes, and cosmic censorship: A tribute to Roger Penrose
• Quasi-local black hole horizons
• Hawking versus Unruh effects, or the difficulty of slowly crossing a black hole horizon
• Self-consistent description of a spherically-symmetric gravitational collapse
• Black holes as frozen stars
• Dynamics and entanglement in spherically symmetric quantum gravity
• Equations for general shells
• Fermionic greybody factors in dilaton black holes
• Algorithms for the explicit computation of Penrose diagrams
• Geometric surfaces: An invariant characterization of spherically symmetric black hole horizons and wormhole throats
• The Vaidya metric: expected and unexpected traits of evaporating black holes
• Pandora's box lid: geometry near the apparent horizon
• Universal properties of the near-horizon geometry
• Kerr-Vaidya black holes
• A tensorial description of particle perception in black-hole physics
• Stability of self-dual black holes
• Semiclassical black holes and horizon singularities
• The ACTIONFINDER: An unsupervised deep learning algorithm for calculating actions and the acceleration field from a set of orbit segments
• Transition to light-like trajectories in thin shell dynamics
• Model for Quantum Effects in Stellar Collapse
• Planckian Physics Comes Into Play At Planckian Distance From Horizon
• Vacuum solutions around spherically symmetric and static objects in the Starobinsky model
• Cutoffs, Stretched Horizons and Black Hole Radiators
• Physical black holes in fourth-order gravity
• Understanding black hole evaporation using explicitly computed Penrose diagrams
• Vaidya Spacetime in the Diagonal Coordinates
• Unruh-DeWitt Detector Differentiation of Black Holes and Exotic Compact Objects
• On perturbative constraints for vacuum f(R) gravity
• Spherically symmetric black holes in metric gravity
• Evaporating black holes: constraints on anomalous emission mechanisms
• The trapped region
• Averaged Energy Conditions in 4D Evaporating Black Hole Backgrounds
• Probing dynamical spacetimes with gravitational waves
• Quantum ergosphere and brick wall entropy
• Unitarity and the information problem in an explicit model of black hole evaporation
• On the assumptions leading to the information loss paradox