The Simulating eXtreme Spacetimes Collaboration’s code SpEC can now routinely simulate binary black hole mergers undergoing orbits, with the longest simulations undergoing nearly orbits. While this sounds impressive, the mismatch between the highest resolutions for this long simulation is . Meanwhile, the mismatch between resolutions for the more typical simulations tends to be , despite the resolutions

The Laser Interferometer Space Antenna (LISA) will be a space-borne gravitational wave (GW) detector to be launched in the next decade. Central to LISA data analysis is time-delay interferometry (TDI), a numerical procedure which drastically reduces otherwise overwhelming laser frequency noise. LISA data analysis is usually performed on sets of TDI variables, e.g. Michelson variables or quasiorthogonal

Heterodyne detection using microwave cavities is a promising method for detecting high-frequency gravitational waves (GWs) or ultralight axion dark matter. In this work, we report on studies conducted on a spherical 2-cell cavity developed by the MAGO collaboration for high-frequency GWs detection. Although fabricated around 20 years ago, the cavity had not been used since. Due to deviations from the

This work revises the Brane World Theory known as Randall Sundrum with the modification of an exponential, redshift-dependent brane tension. This model is studied in a scenario assuming no dark energy, with the aim of determining whether it can reproduce the Universe’s acceleration on its own, without the addition of a dark energy fluid. Bayesian Statistical analysis is performed in order to constrain

We study the entanglement dynamics of accelerated atoms using the theory of open quantum systems. We consider two atoms traveling along different hyperbolic trajectories with different proper times. We use the generalized master equation to discuss the dynamics of a pair of dipoles interacting with the electromagnetic field. The fundamental role played by proper acceleration in the entanglement harvesting

Gravitational-wave detectors impose exceptionally rigorous demands on optical coatings, which include high reflectivity, low thermal noise, low absorption, low scatter, and minimal defect counts. Simultaneously satisfying the thermal noise and absorption requirements is particularly challenging. One promising approach is to use three or more materials in a single coating. In this work we characterize

We compute families of solutions to the Einstein vacuum equations of the type of Brill waves, but with slow fall-off towards spatial infinity. We prove existence and uniqueness of solutions for physical data and numerically construct some representative solutions. We numerically construct an explicit example with slow-off which does not exhibit antipodal symmetry at spatial infinity.

We show that the Fréchet–Lie groups of the form C∞(M)⋊R resulting from smooth flows on compact manifolds M fail to be locally exponential in several cases: when at least one non-periodic orbit is locally closed, or when the flow restricts to a linear one on an orbit closure diffeomorphic to a torus. As an application, we prove that the Bondi–Metzner–Sachs group of symmetries of an asymptotically flat

Space-based gravitational wave detection generally employs kilogram-scale cubic test masses. The flat cuboid test mass for gravity satellites has the advantages of lightweight, low remanent magnetic moment, low preload force requirement and convenient ground testing. The paper analyses the relationship between acceleration noise and dimensions, identifying that the flat cuboid Au–Pt alloy test mass

Supermassive binary black holes (SMBBHs) are natural products of the hierarchical mergers of galaxies with central black holes in the Λ cold dark matter cosmogony. We briefly introduce the formation and evolution processes of SMBBHs and population synthesis modeling of SMBBHs across cosmic time. Both the semi-analytical analysis and numerical simulations suggest that close SMBBHs are abundant in the

We apply Iyer–Wald’s covariant phase space formalism to asymptotically de Sitter spacetimes and establish the thermodynamic first law, expressed in terms of the Abbott–Deser mass. Similar to Iyer–Wald’s first law for asymptotically flat black holes, our first law applies to general asymptotically de Sitter perturbations around a Reissner–Nordström–de Sitter black hole, without imposing any symmetry

Quantum reference frame as in the example of observing a quantum particle from another has been a topic of much recent interest. Quantum spatial translations, quantum rotations, and quantum Lorentz boosts in the sense have been studied to some extent. The article aims at using a consistent formulation of all that to give a full picture of what would be the symmetry of Special Quantum Relativity as

Next-generation gravitational wave (GW) detectors such as Cosmic Explorer, the Einstein Telescope, and LISA, demand highly accurate and extensive GW catalogs to faithfully extract physical parameters from observed signals. However, numerical relativity (NR) faces significant challenges in generating these catalogs at the required scale and accuracy on modern computers, as NR codes do not fully exploit

Modified gravity theories have been suggested to address the limitations of general relativity (GR), each exhibiting differences, particularly in their strong-field limits. Nonetheless, there lacks effective means to distinguish or test these theories through local strong-field measurements. In this work, we define a global Gaussian bending measure over singular spacetime regions, establish a corresponding

In the present work, we investigate the Bose–Einstein condensates (BECs) on electrically charged noncommutative-inspired (NCi) black holes (BHs). The NC parameter represents a quantum correction that modifies spacetime geometry by introducing a minimal length scale. This impacts the BH’s effective gravitational field and, consequently, the dynamics of nearby scalar fields. The BEC is represented by

We consider the classical minisuperspace model describing a closed, homogeneous and isotropic Universe, with a positive cosmological constant. Upon canonical quantization, the infinite number of possible operator orderings in the quantum Hamiltonian leads to distinct Wheeler–DeWitt (WDW) equations for the wavefunction ψ of the Universe. Similarly, ambiguity arises in the path-integral formulation of

Time-delay interferometry (TDI) suppresses laser frequency noise by forming linear combinations of time-shifted interferometric measurements. The time-shift operation is implemented by interpolating discretely sampled data. To enable in-band laser noise reduction by eight to nine orders of magnitude, interpolation has to be performed with high accuracy. Interpolation can be understood as the convolution

We develop and characterize a parameter estimation methodology for rotating core collapse supernovae based on the gravitational wave (GW) core bounce phase and real detector noise. Expanding on the evidence from numerical simulations for the deterministic nature of this GW emission and about the dependence on the ratio β between rotational kinetic to potential energy, we propose an analytical model

We study the intrinsic and extrinsic torsions (defined by analogy with the intrinsic and extrinsic curvatures) of the spatial sections of torsional spacetimes. We consider two possibilities. First, that the intrinsic torsion might prove to be directly observable. Second, that it is not observable, having been ‘inflated away’ in the early Universe. We argue that, even in this second case, the extrinsic

Penrose’s strong cosmic censorship (SCC) conjecture safeguards determinism in general relativity (GR). Within the initial value approach to GR, proof of SCC preservation is predicated on the unique evolution of the metric. For the Kerr–Newman family of black hole solutions, this requires the inextendibility of the metric past the Cauchy horizon, due to the development of a ‘blue-shift’ instability

Trace-free Einstein gravity, in the absence of matter fields and using the Friedmann–Robertson–Walker (FRW) metric, is solvable both classically and quantum mechanically. This is achieved by using the conformal time as the time variable and the negative or positive of the inverse of the scale factor as configuration variable to write the classical equation of motion, which turns out to be the one of

As the property of duality exists in various disciplines of physics since early times, it is important to look for the existence of this symmetry in the physics of black holes described by quantum gravity. While canonically quantizing gravity, it is well-known that ambiguity in operator ordering and the requirement of Hermiticity play their crucial roles in determining the wave function of the black

The public release of data from the LIGO and Virgo detectors has enabled the identification of potential gravitational wave signals by independent teams using alternative methodologies. In addition to the LIGO-Virgo-KAGRA (LVK) collaboration’s GWTC-3 catalogue there have been several additional works claiming the detection of signals in the data from the first three observing runs. In this paper we

Let k be a nontrivial finite-dimensional Lie algebra of vector fields on a manifold M, and consider the family of Lorentzian metrics on M whose Killing algebra contains k. We show that scalar relative differential invariants of such metrics, with respect to a Lie algebra of vector fields on M preserving k, can be used to detect the horizons of several well-known black holes. In particular, using the

In this paper, we describe the multi-band template analysis search pipeline dedicated to the detection of compact binary coalescence gravitational wave signals from the data obtained by the LIGO-Virgo-KAGRA collaboration during the fourth observing run (O4), which started in May 2023. We give details on the configuration of the pipeline and its evolution compared to the third observing run (O3). We

This article investigates the spacetime of two colliding sandwich gravitational waves, focusing on evaluating gravitational energy before and after the collision. In the framework of the teleparallel equivalent of general relativity (TEGR), we derive a true energy–momentum tensor for the gravitational waves and integrate it over a finite region of space, obtaining analytical expressions for the energy

Future gravitational wave observation in space will demand improvement in the sensitivity of the local sensor for the drag-free control. This paper presents the proposal, design, and demonstration of a new laser interferometric sensor named Quadrature Interferometric Metrology of Translation and Tilt (QUIMETT) for the drag-free local sensor. QUIMETT enables simultaneous measurements of both translational

Glitches are non-Gaussian noise transients originating from environmental and instrumental sources that contaminate data from gravitational wave detectors. Some glitches can even mimic gravitational wave signals from compact object mergers, which are the primary targets of terrestrial observatories. In this study, we present a method to analyze noise transients from the Laser Interferometer Gravitational-Wave

In general relativity (GR), all asymptotically flat, stationary and axisymmetric vacuum black holes are described by the Kerr solution. Beyond GR, there is a prevailing expectation that deviations from the Kerr solution increase with the horizon curvature. We challenge this expectation by showing that, in a scalar-Gauss–Bonnet theory, black holes scalarize in a finite, adjustable window of black-hole

We numerically study, under a Gowdy symmetry assumption, nonlinear perturbations of the decelerated FLRW fluid solutions to the Einstein–Euler system toward the future for linear equations of state p=Kρ with 0⩽K⩽1. This article builds on the work of Fajman et al (2024 arXiv:2405.03431) in which perturbations of the homogeneous fluid solution on a fixed, decelerating FLRW background were studied. Our

The surface of the coating or substrate structure has a rough topological structure over multiple scales, which significantly affects the actual contact area and adhesion strength. In order to investigate potential interferences during the test mass (TM) release process of the locking and release mechanism in TianQin space-borne gravitational wave detection project, an analytical model of the Johnson–Kendall–Roberts

Data preprocessing is an essential step in space-borne gravitational wave detection, aimed at calibrating the data while suppressing noise. Time delay interferometry represents the primary technique for eliminating laser frequency noise, relying on precise arm length information. In this study, we combined pseudo-random noise ranging and Doppler measurements from TianQin’s data to create an observation

In this work we introduce a criterion for testing general covariance in effective quantum gravity theories. It adapts the analysis of invariance under general spacetime diffeomorphisms of the Einstein–Hilbert action to the case of effective canonical models. While the main purpose is to test models obtained in loop quantum gravity, the criterion is not limited to those physical systems and may be applied

We re-consider the graviton self-energy induced by a loop of massless, minimally coupled scalars on de Sitter background. On flat space background it can be represented as a sum of two tensor differential operators acting on scalar structure functions. On a general background these differential operators can be constructed from the linearized Ricci scalar and the linearized Weyl tensor. However, in

TianQin is proposed to detect gravitational wave signals at the frequency band of 0.1mHz−1Hz in space. Given that the residual acceleration noise of the test mass in TianQin is required to be below 10−15ms−2Hz−1/2, all disturbing forces acting on the test mass should be estimated with the required precision. The magnetic force caused by eddy current is one of the error sources and should be treated

We investigate the properties of a charged rotating black string immersed in a Kiselev anisotropic fluid in anti-de Sitter (AdS) spacetime. The Einstein–Maxwell equations with an anisotropic stress–energy tensor and cosmological constant are analyzed and solved exactly. In this work, we calculate the Kretschmann scalar, obtaining a consistent result that agrees with the existing literature in the absence

Next-generation gravitational wave detectors are expected to increase their sensitivity in the kHz band where binary neutron star (NS) remnants are expected to emit. In this context, robust predictions of oscillation modes of the post-merger object are desirable. To that end, we present here our code Relativistic Oscillations of non-aXisymmetric neutron stArS (ROXAS) that is aimed at simulating isolated

In this work, standard methods of the mixed thin-shell formalism are refined using the framework of Colombeau’s theory of generalized functions. To this end, systematic use is made of smooth generalized functions, in particular regularizations of the Heaviside step function and the delta distribution, instead of working directly with the corresponding Schwartz distributions. Based on this change of

In this article we examine a Hamiltonian constraint operator governing the dynamics of simple quantum states, whose graph consists of a single six-valent vertex, in quantum-reduced loop gravity. To this end, we first derive the action of the Hamiltonian constraint on generic basis states in the Hilbert space of quantum-reduced loop gravity. Specializing to the example of the single-vertex states, we

Gravitational Wave (GW) signals from binary neutron star (BNS) mergers provide critical insights into the properties of matter under extreme conditions. Due to the scarcity of observational data, numerical relativity (NR) simulations are indispensable for exploring these phenomena, without replacing the need for observational confirmation. However, simulating BNS mergers is a formidable challenge,

We examine Friedmann–Lemaître–Robertson–Walker cosmology, incorporating quantum gravitational corrections through the functional renormalisation group flow of the effective action for gravity. We solve the Einstein equation with quantum improved coupling perturbatively including the case with non-vanishing classical cosmological constant (CC) which was overlooked in the literatures. We discuss what

In recent years there have been many studies on exactly solvable black hole mergers, based on a model by Emparan and Martínez where the mass of one black hole is blown up to infinity (Emparan and Martínez 2016 Class. Quantum Grav. 33 155003). Here we replace the large black hole by a cosmological horizon, and study how it merges with a black hole in the Schwarzschild-de Sitter spacetime by considering

In their seminal 1992 paper, Bañados, Teitelboim and Zanelli (BTZ) proposed a simple charged generalization of what is now known as the spinning BTZ black hole, the proposal being that a rotating metric can be supported by a ‘static vector’ potential. While with such an ansatz the Einstein equations are satisfied, and the corresponding energy-momentum tensor is divergence-less, the Maxwell equations

Some time ago, Seiberg and Witten solved for moduli spaces of vacua parameterized by scalar vacuum expectation values in N=2 gauge theories. More recently, new vacua associated to soft theorems and asymptotic symmetries have been found. This paper takes some first steps towards a complete picture of the infrared geometry of N=2 gauge theory incorporating both of these infrared structures.

We exhibit the first analogue model of a rotating black hole constructed in the framework of nonlinear electrodynamics. The background electromagnetic field is assumed to be algebraically special and adapted to a geodesic shear-free congruence of null rays in Minkowski spacetime, the Kerr congruence. The corresponding optical metric has a Kerr–Schild form and, it is shown to be characterized by three

The rigorous conditions for obtaining sensible predictions in non (proper) renormalizable quantum field theories were derived a long time ago, most notably in the works of Steven Weinberg. In this paper we explicitly illustrate the challenges met in carrying this program within the affine gravity framework, in particular when attempting to pinpoint viable particle propagation. We explore the one-loop

The impact of space weather on space mission performance is a subject of extensive study by both scientists and space agencies. In this work, we discuss solar activity, the characterization of the interplanetary medium and the fluxes of solar and galactic particles after 2035, when laser interferometer space antenna (LISA), the first interferometer for low-frequency gravitational wave detection in

A Wick rotation in the lapse (not in time) is introduced that interpolates between Riemannian and Lorentzian metrics on real manifolds admitting a codimension-one foliation. The definition refers to a fiducial foliation but covariance under foliation changing diffeomorphisms can be rendered explicit in a reformulation as a rank one perturbation. Applied to scalar field theories a Lorentzian signature

We investigate the possibility of the existence of a classical version of Hawking radiation—solutions to classical field equations that consist solely of outgoing waves, in the spacetime of a collapsing black hole (BH). The non-static nature of the corresponding metric results in the absence of energy conservation for matter, which could otherwise a priori prohibit such solutions. A specific and simple

We provide a characterisation of the Kerr spacetime close to future null infinity using the asymptotic characteristic initial value problem in a conformally compactified spacetime. Stewart’s gauge is used to set up the past-oriented characteristic initial value problem. By a theorem of M. Mars characterising the Kerr spacetime, we provide conditions for the existence of an asymptotically timelike Killing

This paper explores the phenomenon of particle creation associated with cosmic strings (CS) in de Sitter spacetime, a model that represents the Universe’s exponential expansion. We examine how the presence of CSs in a de Sitter background affects particle production, focusing on the roles of string tension and angular deficits. Utilizing the Klein–Gordon equation adapted to curved spacetime with CS

The regularization of the scalar constraint and the Fermion coupling problem indicate that it is necessary to consider some kind of gauge fixing methods to deal with the simplicity constraint in all dimensional SO(D+1) loop quantum gravity (LQG). The coherent state with well-behaved peakedness property is an essential ingredient to carry out the gauge fixing method. To provide the basic tool for constructing

Third generation ground-based gravitational wave detectors are proposing the use of cryogenics. The low-temperature regime will require a cooling-down system capable of removing heat from test masses and maintaining its low temperature. The present study analyzes the Newtonian noise introduced by rotating impellers used in a cooling-down system with sub-cooled nitrogen circulating in a loop. In order

Progress in gravitational-wave (GW) astronomy depends upon having sensitive detectors with good data quality. Since the end of the Laser Interferometer Gravitational-Wave Observatory-Virgo-KAGRA third Observing run in March 2020, detector-characterization efforts have lead to increased sensitivity of the detectors, swifter validation of GW candidates and improved tools used for data-quality products

We construct an effective cosmological spin-foam model for a (2+1) dimensional spatially flat Universe, discretized on a cubical lattice, containing both space- and time-like regions. Our starting point is the recently proposed coherent state spin-foam model for (2+1) Lorentzian quantum gravity. The full amplitude is assumed to factorize into single vertex amplitudes with boundary data corresponding

We present a covariant description of non-vacuum static spherically symmetric spacetimes in f(R) gravity applying the (1+1+2) covariant formalism. The propagation equations are then used to derive a covariant and dimensionless form of the Tolman–Oppenheimer–Volkoff equations. We then give a solution strategy to these equations and obtain some new exact solutions for the particular case f(R)=R+αR2,

In this paper we study the behavior of test particles on top of a galactic-type of fuzzy dark matter (FDM) structure, characterized by the core–halo density profile found in simulations. Our workhorse structure is an anisotropic, time-dependent, virialized core–tail FDM clump resulting from a multicore merger. For our analysis we allow this structure to keep evolving, which implies that the core oscillates

Polymer models have been used to describe non-singular quantum black holes, where the classical singularity is replaced by a transition from a black hole to a white hole. In a previous letter, in the context of a uni-parametric model with asymptotic flat exterior metric, we fixed the radius of the transition surface through the identification of its area with the area gap of loop quantum gravity. This

We analyze existence and properties of solutions of two-dimensional general relativistic initial data sets with a negative cosmological constant, both on spacelike and characteristic surfaces. A new family of such vacuum spacelike data parameterised by poles at the conformal boundary at infinity is constructed. We review the notions of global Hamiltonian charges, emphasizing the difficulties arising

We obtain semiclassical gravity solutions in the Poincaré fundamental domain of (3+1)-dimensional Anti-de Sitter spacetime, PAdS4, with a (massive or massless) Klein–Gordon field (with possibly non-trivial curvature coupling) with Dirichlet or Neumann boundary. Some results are explicitly and graphically presented for special values of the mass and curvature coupling (e.g. minimal or conformal coupling)