scholarly journals Light-ray operators, detectors and gravitational event shapes

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Riccardo Gonzo ◽  
Andrzej Pokraka
Keyword(s):  
Classical Limit ◽  
Compact Objects ◽  
Einstein Equations ◽  
Direct Connection ◽  
Leading Order ◽  
Null Infinity ◽  
Quantum Operator ◽  
Wave Event ◽  
Event Shapes ◽  
Celestial Sphere

Abstract Light-ray operators naturally arise from integrating Einstein equations at null infinity along the light-cone time. We associate light-ray operators to physical detectors on the celestial sphere and we provide explicit expressions in perturbation theory for their hard modes using the steepest descent technique. We then study their algebra in generic 4-dimensional QFTs of massless particles with integer spin, comparing with complexified Cordova-Shao algebra. For the case of gravity, the Bondi news squared term provides an extension of the ANEC operator at infinity to a shear-inclusive ANEC, which as a quantum operator gives the energy of all quanta of radiation in a particular direction on the sky. We finally provide a direct connection of the action of the shear-inclusive ANEC with detector event shapes and we study infrared-safe gravitational wave event shapes produced in the scattering of massive compact objects, computing the energy flux at infinity in the classical limit at leading order in the soft expansion.

scholarly journals Asymptotic symmetries and celestial CFT

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Laura Donnay ◽  
Sabrina Pasterski ◽  
Andrea Puhm
Keyword(s):  
Principal Series ◽  
Finite Energy ◽  
Continuous Series ◽  
Asymptotic Symmetry ◽  
Null Infinity ◽  
Conformal Dimension ◽  
Contour Integrals ◽  
Celestial Sphere ◽  
Goldstone Modes ◽  
Asymptotic Symmetries

Abstract We provide a unified treatment of conformally soft Goldstone modes which arise when spin-one or spin-two conformal primary wavefunctions become pure gauge for certain integer values of the conformal dimension ∆. This effort lands us at the crossroads of two ongoing debates about what the appropriate conformal basis for celestial CFT is and what the asymptotic symmetry group of Einstein gravity at null infinity should be. Finite energy wavefunctions are captured by the principal continuous series ∆ ∈ 1 + iℝ and form a complete basis. We show that conformal primaries with analytically continued conformal dimension can be understood as certain contour integrals on the principal series. This clarifies how conformally soft Goldstone modes fit in but do not augment this basis. Conformally soft gravitons of dimension two and zero which are related by a shadow transform are shown to generate superrotations and non-meromorphic diffeomorphisms of the celestial sphere which we refer to as shadow superrotations. This dovetails the Virasoro and Diff(S2) asymptotic symmetry proposals and puts on equal footing the discussion of their associated soft charges, which correspond to the stress tensor and its shadow in the two-dimensional celestial CFT.

scholarly journals Plausible families of compact objects with a nonlocal equation of state

2013 ◽  
Vol 91 (4) ◽  
pp. 328-336 ◽  
Author(s):  
H. Hernández ◽  
L.A. Núñez
Keyword(s):  
Equation Of State ◽  
Total Mass ◽  
Radial Pressure ◽  
Compact Objects ◽  
Einstein Equations ◽  
Matter Distribution ◽  
Nonlocal Equation ◽  
The Family ◽  
Model Independent ◽  
Physical Variables

We present the plausibility of some models emerging from an algorithm devised to generate a one-parameter family of interior solutions for the Einstein equations. We explore how their physical variables change as the family parameter varies. The models studied correspond to anisotropic spherical matter configurations having a nonlocal equation of state. This particular type of equation of state, with no causality problems, provides at a given point the radial pressure not only as a function of the density but as a functional of the enclosed matter distribution. We have found that there are several model-independent tendencies as the parameter increases: the equation of state tends to be stiffer and the total mass becomes half of its external radius. Profiting from the concept of cracking of materials in general relativity, we obtain that these models become more potentially stable as the family parameter increases.

The two-body problem and radiative losses

2018 ◽  
Author(s):  
Nathalie Deruelle ◽  
Jean-Philippe Uzan
Keyword(s):  
Mechanical Energy ◽  
Equations Of Motion ◽  
Reaction Force ◽  
Radiation Reaction ◽  
Compact Objects ◽  
Einstein Equations ◽  
Two Body Problem ◽  
System P ◽  
Radiative Losses ◽  
Radiation Reaction Force

This chapter begins by finding the field created by compact objects in the post-linear approximation of general relativity. The second quadrupole formula is then completely proven. Next, the chapter finds the equations of motion of the bodies in the field which they create to second order in the perturbations, assuming that their velocities are small. It shows that, to correctly describe the radiation reaction at 2.5 PN order, it will prove necessary to iterate Einstein equations a third time. This leads the discussion to the equations of motion, which generalize to order 1/c5 the EIH equations of order 1/c⁲. Finally, the chapter studies the effect of the radiation reaction force on the sources, and shows that there is an energy balance at 2.5 PN order between the energy radiated to infinity and the mechanical energy lost by the system.

scholarly journals Regularity condition on the anisotropy induced by gravitational decoupling in the framework of MGD

2020 ◽  
Vol 80 (2) ◽  
Author(s):  
G. Abellán ◽  
V. A. Torres-Sánchez ◽  
E. Fuenmayor ◽  
E. Contreras
Keyword(s):  
Standard Method ◽  
Regularity Condition ◽  
Physical Characteristics ◽  
Compact Objects ◽  
Anisotropy Factor ◽  
Einstein Equations ◽  
Anisotropic Fluid ◽  
Acceptable Solution ◽  
Geometric Deformation ◽  
Deformation Approach

Abstract We use gravitational decoupling to establish a connection between the minimal geometric deformation approach and the standard method for obtaining anisotropic fluid solutions. Motivated by the relations that appear in the framework of minimal geometric deformation, we give an anisotropy factor that allows us to solve the quasi–Einstein equations associated to the decoupling sector. We illustrate this by building an anisotropic extension of the well known Tolman IV solution, providing in this way an exact and physically acceptable solution that represents the behavior of compact objects. We show that, in this way, it is not necessary to use the usual mimic constraint conditions. Our solution is free from physical and geometrical singularities, as expected. We have presented the main physical characteristics of our solution both analytically and graphically and verified the viability of the solution obtained by studying the usual criteria of physical acceptability.

scholarly journals Strong-field gravitational-wave emission in Schwarzschild and Kerr geometries: some general considerations

2018 ◽  
Vol 168 ◽  
pp. 02006 ◽  
Author(s):  
J.F. Rodríguez ◽  
J.A. Rueda ◽  
R. Ruffini
Keyword(s):  
Black Hole ◽  
Test Particle ◽  
Strong Field ◽  
Reaction Force ◽  
Dynamical Evolution ◽  
Radiation Reaction ◽  
Compact Objects ◽  
Einstein Equations ◽  
Smooth Transition ◽  
Wave Emission

We have used the perturbations of the exact solutions of the Einstein equations to estimate the relativistic wave emission of a test particle orbiting around a black hole. We show how the hamiltonian equations of motion of a test particle augmented with the radiation-reaction force can establish a priori constraints on the possible phenomena occurring in the merger of compact objects. The dynamical evolution consists of a helicoidal sequence of quasi-circular orbits, induced by the radiation-reaction and the background spacetime. Near the innermost stable circular orbit the evolution is followed by a smooth transition and finally plunges geodesically into the black hole horizon. This analysis gives physical insight of the merger of two equal masses objects.

scholarly journals Regularity of the Einstein equations at future null infinity

2009 ◽  
Vol 26 (12) ◽  
pp. 125010 ◽  
Author(s):  
Vincent Moncrief ◽  
Oliver Rinne
Keyword(s):  
Einstein Equations ◽  
Null Infinity ◽  
Future Null Infinity

scholarly journals THE VALUE OF THE COSMOLOGICAL CONSTANT

2011 ◽  
Vol 20 (14) ◽  
pp. 2875-2880 ◽  
Author(s):  
JOHN D. BARROW ◽  
DOUGLAS J. SHAW
Keyword(s):  
Wave Function ◽  
Cosmological Constant ◽  
Classical Limit ◽  
Constraint Equation ◽  
Einstein Equations ◽  
Spatial Curvature ◽  
Self Consistent ◽  
Curvature Parameter ◽  
The Universe ◽  
Planck Satellite

We make the cosmological constant, Λ, into a field and restrict the variations of the action with respect to it by causality. This creates an additional Einstein constraint equation. It restricts the solutions of the standard Einstein equations and is the requirement that the cosmological wave function possess a classical limit. When applied to the Friedmann metric it requires that the cosmological constant measured today, tU, be [Formula: see text], as observed. This is the classical value of Λ that dominates the wave function of the universe. Our new field equation determines Λ in terms of other astronomically measurable quantities. Specifically, it predicts that the spatial curvature parameter of the universe is [Formula: see text], which will be tested by Planck Satellite data. Our theory also creates a new picture of self-consistent quantum cosmological history.

scholarly journals DUALISM BETWEEN PHYSICAL FRAMES AND TIME IN QUANTUM GRAVITY

2004 ◽  
Vol 19 (20) ◽  
pp. 1519-1527 ◽  
Author(s):  
SIMONE MERCURI ◽  
GIOVANNI MONTANI
Keyword(s):  
Quantum Gravity ◽  
Reference Frame ◽  
Path Integral ◽  
Classical Limit ◽  
Quantum Dynamics ◽  
Einstein Equations ◽  
Quantum Level ◽  
Dust Fluid ◽  
Lapse Function ◽  
Canonical Quantum

In this work we present a discussion of the existing links between the procedures of endowing the quantum gravity with a real time and of including in the theory a physical reference frame. More precisely, as a first step, we develop the canonical quantum dynamics, starting from the Einstein equations in presence of a dust fluid and arrive at a Schrödinger evolution. Then, by fixing the lapse function in the path-integral of gravity, we get a Schrödinger quantum dynamics, of which eigenvalues problem provides the appearance of a dust fluid in the classical limit. The main issue of our analysis is to claim that a theory, in which the time displacement invariance, on a quantum level, is broken, is indistinguishable from a theory for which this symmetry holds, but a real reference fluid is included.

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