General Relativity and Quantum Cosmology
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Showing new listings for Friday, 17 January 2025
- [1] arXiv:2501.09057 [pdf, html, other]
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Title: Impact of correlated noise on the reconstruction of the stochastic gravitational wave background with Einstein TelescopeComments: 10 pages, 5 figures, 4 appendicesSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Einstein Telescope (ET) is a proposed next-generation Gravitational Wave (GW) interferometer designed to detect a large number of astrophysical and cosmological sources with unprecedented sensitivity. A key target for ET is the detection of a stochastic gravitational-wave background (SGWB), a faint signal from unresolved GW sources. In its proposed triangular configuration, correlated Newtonian noise of seismic origin poses some challenges for the SGWB detection. We study the impact of correlated noise on the SGWB detection and relative parameter estimation for ET in the triangular configuration, comparing it to a 2L configuration with two separated L-shaped detectors. We perform a Bayesian analysis on simulated data, which shows that accurate reconstruction of the SGWB parameters and instrumental noise is achievable if the noise is properly modeled. We illustrate that neglecting correlated noise leads to significant biases in the parameter reconstruction. Our results show that while the 2L configuration provides slightly better parameter estimation precision, mainly due to its longer arm length, the triangular configuration remains competitive when accurate noise modeling is provided.
- [2] arXiv:2501.09151 [pdf, html, other]
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Title: Loop Quantum Gravitational Signatures via Love NumbersComments: 17 pages, 3 figuresSubjects: General Relativity and Quantum Cosmology (gr-qc)
Loop quantum gravitational effects can resolve the central singularity of black holes while potentially leaving tiny traces of quantization in the exterior spacetime. We show the way these residues can, in principle, be explored using tidal Love numbers (TLNs). We consider loop quantized Schwarzschild black hole, in particular the Ashtekar-Olmedo-Singh (AOS) model, and study the static response to external tidal fields of spin zero (scalar field), spin one (vector field), and spin two (axial gravitational field) types. We find that, in contrast to the classical theory, where TLNs vanish, they are non-vanishing and negative for all three responses and for all multipoles. Besides, the magnitude of TLNs decreases as the black hole mass increases, and TLNs, in response to the axial gravitational field, have the largest magnitude among these three responses. Our results show that for black holes of mass $M \gtrsim 4.3 \times 10^{4} M_{\textrm{Pl}}$, the AOS model is consistent with current and next-generation detection limits for TLNs. Our findings suggest that the quantum deformability of loop quantum black holes, arising from the inherent fuzziness of spacetime geometry, reveals a fundamentally distinct internal structure compared to their classical counterparts. This unique feature manifests as quantum hair, which, in principle, can be detected by future observations.
- [3] arXiv:2501.09177 [pdf, html, other]
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Title: Cosmological Interactions with Phantom Scalar Field: Revisiting Background Phase-Space Analysis with Compactified VariablesComments: 18 pages, 2 tables, 8 compound figuresSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)
Energy transfer in the dark sector of the universe gives rise to new phenomena of special interest in modern cosmology. When dark energy is modeled as a phantom scalar field, interactions become crucial to avoid Big Rip singularities. In this work, we revisit the phase-space analysis of the field equations by introducing a new set of dimensionless variables distinct from the traditional Hubble normalization approach. These new variables define a compactified phase space for the evolution of physical parameters. We demonstrate that these compactified variables offer fresh insights into the phase-space analysis in gravitational theories, particularly when the dark energy fluid is allowed to possess a negative kinetic energy density.
- [4] arXiv:2501.09247 [pdf, html, other]
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Title: Physical characteristics and causality of cosmological models in generalized matter-geometry coupling gravity theory with observational constraintsComments: 23 pages, 8 figuresSubjects: General Relativity and Quantum Cosmology (gr-qc)
In the generalized matter-geometry coupling theory, we investigate the physical characteristics and causality of some new cosmological models for a flat, homogeneous, and isotropic spacetime filled with stiff, radiation, dust, and curvature fluid sources. We obtain a particular cosmological model corresponding to each source fluid, called Models I, II, III, and IV, respectively. We make observational constraints on each model using the joint analysis of $31$ Cosmic Chronometer (CC) Hubble dataset and $1048$ Pantheon datasets to estimate the current values of model parameters. Using these statistical results, we have analyzed the information criteria, effective EoS parameter, causality of the models, and viability of this generalized gravity theory. Subsequently, we investigate the effective equation of state and deceleration parameter for each model. We found that all models in the late-time universe exhibit transit-phase acceleration, and Models I and II show both the early as well as late-time accelerating phase of the expanding universe. We found the current values of the deceleration parameter in the range $-0.886\le q_{0}\le-0.54$ with transition redshift $0.5137\le z_{t}\le0.6466$ and the effective EoS parameter in the range $-0.924\le\omega_{eff}\le-0.6933$. We analyzed the square sound speed condition $c_{s}^{2}\le c^{2}$ for each model.
- [5] arXiv:2501.09280 [pdf, html, other]
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Title: The effect of accretion on scalar superradiant instabilityComments: 29 pages, 8 figureSubjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)
Superradiance can lead to the formation of a black hole (BH) condensate system. We thoroughly investigate the accretion effect on the evolution of this system, and the gravitational wave signals it emits in the presence of multiple superradiance modes. Assuming the multiplication of the BH mass and scalar mass as a small number, we obtain the analytical approximations of all important quantities, which can be directly applied to phenomenological studies. In addition, we confirm that accretion could significantly enhance the gravitational wave (GW) emission and reduce its duration, and show that the GW beat signature is similarly modified.
- [6] arXiv:2501.09317 [pdf, html, other]
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Title: Super-entropy bumblebee AdS black holesComments: 10 pages, 3 figures. Accepted for publication in Physics Letters BSubjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
Motivated by the effect of the bumblebee field on thermodynamic instability in (non)extended phase space, we study the thermodynamic instability for the bumblebee AdS black holes. For this purpose, first, we evaluate the effect of the bumblebee field (or Lorentz-violating parameter) on the event horizon for AdS black holes. Then, in non-extended phase space, we study the effect of the bumblebee field on the heat capacity and the Helmholtz free energy to investigate the local and global thermal stability areas, respectively. Next, we extend our study on the extended phase space by seeking on stable area by using the heat capacity at constant pressure ($C_{P}$). Finally, we evaluate the super-entropy black hole condition and indicate that the bumblebee AdS black holes are super-entropy black holes when $l>0$, which is consistent with the condition $C_{P}<0$.
- [7] arXiv:2501.09356 [pdf, html, other]
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Title: Cosmological Solutions in Scalar-Tensor theory via the Eisenhart-Duval liftComments: 19 pages, no figures, to appear in Modern Physics Letters ASubjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph); Mathematical Physics (math-ph)
We implement the Einsenhart-Duval lift in scalar-tensor gravity as a means to construct integrable cosmological models and analytic cosmological solutions. Specifically, we employ a geometric criterion to constrain the free functions of the scalar-tensor theory such that the field equations can be written in the equivalent form of linear equations. This geometric linearization is achieved by the introduction of an extended minisuperspace description. The results are applied to construct analytic solutions in modified theories of gravity such as the $f\left( R\right) $-theory and the hybrid metric-Palatini $f\left( \mathcal{R}\right) $-gravity.
- [8] arXiv:2501.09373 [pdf, html, other]
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Title: Maxwell-$f(Q)$ theoryComments: 10 pages two figuresJournal-ref: Fortsch.Phys. 72 (2024) 7-8, 2400037Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
Exploring the four-dimensional AdS black hole is crucial within the framework of the AdS/CFT correspondence. In this research, considering the charged scenario, we investigate the four-dimensional stationary and rotating AdS solutions in the framework of the $f(Q)$ gravitational theory. Our emphasis is on the power-law ansatz, which is consistent with observations and is deemed the most viable. Because this solution does not have an uncharged version or relate to general relativity, it falls into a new category, which derives its features from changes in non-metricity and incorporates the Maxwell domain. We analyze the singularities of such a solution, computing all the quantities of different curvature and non-metricity invariants. Our results indicate the presence of a central singularity, albeit with a softer nature compared to standard non-metricity or Einstein general relativity, attributed to the influence of the effect of $f(Q)$. We examine several physical characteristics of black holes from a thermodynamics perspective and demonstrate the existence of an outer event horizon in addition to the inner Cauchy horizons. However, under the conditions of a sufficiently large electric charge, a naked singularity emerges. Finally, we derive a class of rotating black hole in four-dimensional $f(Q)$ gravity that are asymptotically anti-de Sitter charged.
- [9] arXiv:2501.09375 [pdf, html, other]
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Title: Thermodynamics of charged rotating black strings in extended phase spaceComments: 15 Pages, 6 figuresSubjects: General Relativity and Quantum Cosmology (gr-qc)
We investigate the thermodynamics of asymptotically Anti-de Sitter charged and ro- tating black strings in extended phase space, in which the cosmological constant is in- terpreted as thermodynamic pressure and the thermodynamic volume is defined as its conjugate. We find, the thermodynamic volume, the internal energy, and the Smarr law. We study the thermal stability of solusions and show that some of the solutions have positive specific heat, which makes them thermodynamically stable. We also study the maximal efficiency of a Penrose process for solutions and find that an extremal rotating black string can have an efficiency of up to 50% compared to the corresponding value of 0%, when the cosmological constant is zero. We also find the equation of state for uncharged solutions. By comparing with the liquid-gas system, we observe that there is not a critical behavior to coincide with those of the Van der Waals system.
- [10] arXiv:2501.09439 [pdf, html, other]
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Title: Observable Signatures of RN Black Holes with Dark Matter Halos via Strong Gravitational Lensing and Constraints from EHT ObservationsNiyaz Uddin Molla, Himanshu Chaudhary, Salvatore Capozziello, Farruh Atamurotov, G. Mustafa, Ujjal DebnathComments: 27 pages, 18 figures, Published in Physics of the Dark UniverseSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
We investigate the impact of dark matter halos on the gravitational lensing produced by electrically charged, spherically symmetric black holes in the strong-field regime. The study focuses on two dark matter models: the Universal Rotation Curve Model and the cold dark matter model. We derive the coefficients for the strong deflection limit and numerically analyze the deflection angle variations. Graphical representations of the results show that the strong deflection angle, $\alpha_D$ , increases with the charge parameter $Q$ in the presence of a dark matter halo. We explore the astrophysical consequences for the supermassive black holes $M87^*$ and $SgrA^*$ , comparing the results with standard Reissner-Nordström and Schwarzschild black holes via strong gravitational lensing observations. Our findings suggest that charged black holes with dark matter halos can be differentiated from standard black holes. We constrain the charge parameter $Q$ using observational data from the Event Horizon Telescope Collaboration. For $M87^*$ , we find $0 \leq |Q| \leq 0.366M$ with the Universal Rotation Curve model and $0 \leq |Q| \leq 0.364M$ with the cold dark matter model. For $SgrA^*$ , the constraints are $0 \leq |Q| \leq 0.586M$ and $0 \leq |Q| \leq 0.584M$, respectively. These results suggest that charged black holes with dark matter halos satisfy the Event Horizon Telescope constraints, offering potential for future identification in observational campaigns.
- [11] arXiv:2501.09491 [pdf, html, other]
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Title: The quantum relative entropy of the Schwarzschild black-hole and the area lawComments: (6 pages)Subjects: General Relativity and Quantum Cosmology (gr-qc); Statistical Mechanics (cond-mat.stat-mech); Quantum Physics (quant-ph)
The area law obeyed by the thermodynamic entropy of black holes is one of the fundamental results relating gravity to statistical mechanics. In this work we provide a derivation of the area law for the quantum relative entropy of the Schwarzschild black-hole for arbitrary Schwarzschild radius. The quantum relative entropy between the metric of the manifold and the metric induced by the geometry and the matter field has been proposed in G. Bianconi ``Gravity from entropy" (2024) as the action for entropic quantum gravity leading to modified Einstein equations. The quantum relative entropy generalizes Araki entropy and treats the metrics between zero-forms, one-forms, and two-forms as quantum operators. Although the Schwarzschild metric is not an exact solution of the modified Einstein equations of the entropic quantum gravity, it is an approximate solution valid in the low coupling limit. Here we show that the quantum relative entropy associated to the Schwarzschild metric obeys the area law for large Schwarzschild radius. We provide a full statistical mechanics interpretation of the results.
- [12] arXiv:2501.09536 [pdf, html, other]
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Title: Finslerian structure of black holesComments: 9 pages, 2 figuresSubjects: General Relativity and Quantum Cosmology (gr-qc)
Recently, there has been an increasing interest in the Finslerian interpretation of null geodesics in the exterior regions of stationary black holes, particularly through the Zermelo navigation problem and the Randers metric. In this work, we show that recent mathematical advancements in the critical and strong Zermelo navigation problems and their connections to Kropina and Lorentz-Finsler metrics enable the extension of this Finslerian framework to encompass horizons and their interior regions. The Finslerian indicatrix, a key element of this framework, serves as an effective tool for identifying frame-dragging effects and the location of horizons and ergosurfaces. We illustrate our results with explicit physical examples, focusing on spherically symmetric and Kerr black holes. Our findings provide new insights into the "river model" of black holes, offering enhanced visual representations of null geodesics on the ergosurfaces, horizons, and within their interior regions.
- [13] arXiv:2501.09598 [pdf, html, other]
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Title: Cosmic voids and the kinetic analysis. IV. Hubble tension and the cosmological constantComments: 8 pages, A&A (in press)Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
The formation of the cosmic structures in the late Universe is considered using Vlasov kinetic approach. The crucial point is the use of the gravitational potential with repulsive term of the cosmological constant which provides a solution to the Hubble tension, that is the Hubble parameter for the late Universe has to differ from its global cosmological value. This also provides a mechanism of formation of stationary semi-periodic gravitating structures of voids and walls, so that the cosmological constant has a role of the scaling and hence can be compared with the observational data for given regions. The considered mechanism of the structure formation in late cosmological epoch then is succeeding the epoch described by the evolution of primordial density fluctuations.
- [14] arXiv:2501.09676 [pdf, html, other]
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Title: Finite-time Unruh effect: Waiting for the transient effects to fade offComments: v1: 6+5 pagesSubjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th); Quantum Physics (quant-ph)
We investigate the transition probability rate of a Unruh-DeWitt (UD) detector interacting with massless scalar field for a finite duration of proper time, $T$, of the detector. For a UD detector moving at a uniform acceleration, $a$, we explicitly show that the finite-time transition probability rate can be written as a sum of purely thermal terms, and non-thermal transient terms. While the thermal terms are independent of time, $T$, the non-thermal transient terms depend on $(\Delta ET)$, $(aT)$, and $(\Delta E/a)$, where $\Delta E$ is the energy gap of the detector. Particularly, the non-thermal terms are oscillatory with respect to the variable $(\Delta ET)$, so that they may be averaged out to be insignificant in the limit $\Delta ET \gg 1$, irrespective of the values of $(aT)$ and $(\Delta E/a)$. To quantify the contribution of non-thermal transient terms to the transition probability rate of a uniformly accelerating detector, we introduce a parameter, $\varepsilon_{\rm nt}$, called non-thermal parameter. Demanding the contribution of non-thermal terms in the finite-time transition probability rate to be negligibly small, \ie, $\varepsilon_{\rm nt}=\delta\ll1$, we calculate the thermalization time -- the time required for the detector to interact with the field to arrive at the required non-thermality, $\varepsilon_{\rm nt}=\delta$, and the detector to be (almost) thermalized with the Unruh bath in its comoving frame. Specifically, for small accelerations, $a\ll\Delta E$, we find the thermalization time, $\tau_{\rm th}$, to be $\tau_{\rm th} \sim (\Delta E)^{-1} \times {\rm e}^{2\pi|\Delta E|/a}/\delta$; and for large accelerations, $a\gg \Delta E$, we find the thermalization time to be $\tau_{\rm th} \sim (\Delta E)^{-1}/\delta$. We comment on the possibilities of bringing down the exponentially large thermalization time at small accelerations, $a\ll\Delta E$.
New submissions (showing 14 of 14 entries)
- [15] arXiv:2501.08542 (cross-list from astro-ph.CO) [pdf, html, other]
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Title: Broad primordial power spectrum and $\mu$-distortion constraints on primordial black holesComments: 24 pages,7 figues,1 tableSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
Supermassive black holes (SMBHs) might originate from supermassive primordial black holes (PBHs). However, the hypothesis that these PBHs formed through the enhancement of the primordial curvature perturbations has consistently faced significant challenges due to the stringent constraints imposed by $\mu$-distortion in the cosmic microwave background (CMB). In this work, we investigate the impact of non-Gaussianity on $\mu$-distortion constraint in the context of broad power spectra. Our results show that, under the assumption of non-Gaussian curvature perturbations, a broad power spectrum may lead to weaker $\mu$-distortion constraints compared to the Gaussian cases. Our findings highlight the potential of the broad power spectrum to alleviate the $\mu$-distortion constraints on supermassive PBHs under large non-Gaussianity.
- [16] arXiv:2501.09264 (cross-list from hep-th) [pdf, html, other]
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Title: Acceleration temperature for quantum fields without event horizonComments: 16 pagesSubjects: High Energy Physics - Theory (hep-th); General Relativity and Quantum Cosmology (gr-qc)
We investigate unitarily inequivalent representations of the algebra of operators in quantum field theory. In those cases that exist a Fock representation of the commutation relations, we have a unique no-quanta state. We examine more closely the operational definition of a measuring device which detect a quantum of an Hermitian scalar field. The Unruh-DeWitt and Glauber model of quanta detectors are discussed. In Minkowski spacetime, the transition probability per unit proper time of both detectors is studied in two different non-inertial frames of reference. The first one, a detector with a constant proper acceleration, travelling in a stationary worldline, i.e., an hyperbolic motion, interacting with the field prepared in the Poincaré invariant Fock vacuum state. Next, we studied the Unruh-DeWitt detector at rest in a non-uniformly accelerated frame, with a time dependent acceleration. We evaluate the positive frequency Wightman function for the non-uniformly accelerated frame in a finite time interval and obtain the same two-point correlation function of a system in equilibrium with a thermal bath. Therefore the non-uniformly accelerated Unruh-DeWitt detector interacting with the field in the Poincaré invariant Fock vacuum state measures a thermal state. This result shows that the existence of an acceleration temperature without the presence of an event horizon.
- [17] arXiv:2501.09370 (cross-list from hep-th) [pdf, html, other]
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Title: Reassessing aspects of the photon's LQG-modified dispersion relationsComments: 9 pages, 0 figuresSubjects: High Energy Physics - Theory (hep-th); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)
Our present contribution sets out to investigate a scenario based on the effects of the Loop Quantum Gravity (LQG) on the electromagnetic sector of the Standard Model of Fundamental Interactions and Particle Physics (SM). Starting then from a post-Maxwellian version of Electromagnetism that includes LQG effects, we work out and discuss the influence of LQG parameters on classical quantities, such as the components of the stress-tensor. Furthermore, we inspect the propagation of electromagnetic waves and study optical properties of the QED vacuum in this scenario. Among these, we contemplate the combined effect between the LQG parameters and a homogeneous background magnetic field on the propagation of electromagnetic waves, considering in detail issues like group velocities and refractive indices of the QED vacuum. Finally, with the help of the LQG-extended photonic dispersion relations previously analyzed, we re-discuss the kinematics of the Compton effect and conclude that there emerges an interesting nonlinear profile in the wavelengths of both the incoming and the deflected photons.
- [18] arXiv:2501.09537 (cross-list from hep-th) [pdf, html, other]
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Title: One-variable Metrics in String TheoryComments: 13 pagesSubjects: High Energy Physics - Theory (hep-th); General Relativity and Quantum Cosmology (gr-qc)
Exact solutions depending on one variable of gravitational theory with antisymmetric tensor and a coupled dilaton field are obtained in arbitrary space-time dimensions. These solutions are relevant to M-theory, type IIA and type IIB supergravity theories in various space-time signatures.
- [19] arXiv:2501.09627 (cross-list from hep-th) [pdf, html, other]
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Title: Twistorial chiral algebras in higher dimensionsComments: 29+8 pages, no figuresSubjects: High Energy Physics - Theory (hep-th); General Relativity and Quantum Cosmology (gr-qc); Mathematical Physics (math-ph)
In four spacetime dimensions, the classically integrable self-dual sectors of gauge theory and gravity have associated chiral algebras, which emerge naturally from their description in twistor space. We show that there are similar chiral algebras associated to integrable sectors of gauge theory and gravity whenever the spacetime dimension is an integer multiple of four. In particular, the hyperkähler sector of gravity and the hyperholomorphic sector of gauge theory in $4m$-dimensions have well-known twistor descriptions giving rise to chiral algebras. Using twistor sigma models to describe these sectors, we demonstrate that the chiral algebras in higher-dimensions also arise as soft symmetry algebras under a certain notion of collinear limit. Interestingly, the chiral algebras and collinear limits in higher-dimensions are defined on the 2-sphere, rather than the full celestial sphere.
Cross submissions (showing 5 of 5 entries)
- [20] arXiv:2312.14451 (replaced) [pdf, html, other]
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Title: Special $N$-dimensional charged anti-de-Sitter black holes in $f(\mathbb{Q})$ gravitational theoryComments: 13 pages, 3 figures will appear in PLBSubjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
Due to the absence of spherically symmetric black hole solutions in $f(\mathbb{Q})$ because of the constraint derived from its field equations, which yields either $\mathbb{Q}=0 $ or $f_{\mathbb{Q} \mathbb{Q}}=0 $ \cite{Heisenberg:2023lru,Maurya:2023muz}. We are going to introduce a tours solutions for charged anti-de-Sitter black holes in $N$-dimensions within the framework of the quadratic form of $f(\mathbb{Q})$ gravity, where the coincident gauge condition is applied \cite{Heisenberg:2023lru}. Here, $f(\mathbb{Q})=\mathbb{Q}+\frac{1}2\alpha \mathbb{Q}^2-2\Lambda$, and the condition $N \geq 4$ is satisfied. These black hole solutions exhibit flat or cylindrical horizons as their distinctive features. An intriguing aspect of these black hole solutions lies in the coexistence of electric monopole and quadrupole components within the potential field, which are indivisible and exhibit interconnected momenta. This sets them apart from the majority of known charged solutions in the linear form of the non-metricity theory and its extensions. Moreover, the curvature singularities in these solutions are less severe compared to those found in known charged black hole solutions within the characteristic can be demonstrated by computing certain invariants of the curvature and non-metricity tensors. Finally, we calculate thermodynamic parameters, including entropy, Hawking temperature, and Gibbs free energy. These thermodynamic computations affirm the stability of our model.
- [21] arXiv:2409.11991 (replaced) [pdf, html, other]
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Title: Multi-field TDiff theories for cosmologyComments: V2: 14 pages, 7 figures. New section 4.3, figure 5 updated, new references added, this version matches published version. V1: 12 pages, 7 figuresJournal-ref: Phys.Dark. Univ. 47 (2025) 101769Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
We consider theories which break the invariance under diffeomorphisms (Diff) down to transverse diffeomorphisms (TDiff) in the matter sector, consisting of multiple scalar fields. In particular, we regard shift-symmetric models with two free TDiff scalar fields in a flat Robertson-Walker spacetime (FLRW) and use the perfect fluid approach to study their dynamics. As a consequence of the symmetry breaking, an effective interaction between the fields is induced from the conservation of the total energy-momentum tensor, without the necessity to introduce any explicit interacting term in the Lagrangian. We study the different single-field domination regimes and analyze the energy exchange between the fields. Thereupon, we introduce an application of these models for the description of interactions in the dark sector, and compare the theoretical predictions of our model to observational data from Type Ia supernovae.
- [22] arXiv:2409.18728 (replaced) [pdf, html, other]
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Title: Eccentric Binary Black Hole Simulations with Numerical RelativityComments: 14 pages, 12 figures, 8 tablesSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE)
We perform a systematic study of eccentric orbiting nonspinning black hole binaries. We first make a technical study of the optimal full numerical techniques to apply to these studies. We choose different gauge parameters and Courant factors, $c=dx/dt$, and find an optimal value for it of 0.45. We also find the grid structure and global resolution that optimize accuracy and speed of current computational resources. With these choices we perform a study of the merger times $t_m$ as a function of eccentricity for configurations with comparable orbital energy content and find that they are well represented by the post-Newtonian factor $F(e)=(1+73e^2/24+37e^4/96)/(1-e^2)^{7/2}$ when merger times are normalized to their quasicircular values, i.e. $t_m(e)/t_m\approx F(e)$. We then perform a systematic coverage of five small-medium eccentricities up to $e\sim0.45$ and six mass ratios up to 8.5:1 producing a total of 30 simulations covering up to 25 orbits to merger to further model merger times and as a seed to a forthcoming new systematic catalog of gravitational waveforms from eccentric binary black holes to directly perform parameter estimations of gravitational waves events.
- [23] arXiv:2410.02997 (replaced) [pdf, html, other]
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Title: Parameter control for eccentric, precessing binary black hole simulations with SpECComments: 12 pages, 9 figures, accepted to PRDSubjects: General Relativity and Quantum Cosmology (gr-qc)
Numerical relativity simulations of merging black holes provide the most accurate description of the binary dynamics and the emitted gravitational wave signal. However, practical considerations such as imperfect initial data and initial parameters mean that achieving target parameters, such as the orbital eccentricity or the black hole spin directions, at the beginning of the usable part of the simulation is challenging. In this paper, we devise a method to produce simulations with specific target parameters, namely the Keplerian orbital parameters-eccentricity, semimajor axis, mean anomaly-and the black hole spin vectors using SpEC. The method is an extension of the current process for achieving vanishing eccentricity and it is based on a parameter control loop that iteratively numerically evolves the system, fits the orbit with analytical post-Newtonian equations, and calculates updated input parameters. Through SpEC numerical simulations, we demonstrate $\lesssim 10^{-3}$ and $O(\rm degree)$ convergence for the orbital eccentricity and the spin directions respectively in $\leq7$ iterations. These tests extend to binaries with mass ratios $q \leq 3$, eccentricities $e \leq 0.65$, and spin magnitudes $|\chi | \leq 0.75$. Our method for controlling the orbital and spin parameters of numerical simulations can be used to produce targeted simulations in sparsely covered regions of the parameter space or study the dynamics of relativistic binaries.
- [24] arXiv:2410.24161 (replaced) [pdf, html, other]
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Title: Ergoregion instability in a fluid with vorticityComments: 10 pages, 6 figures and 2 tablesJournal-ref: Phys. Rev. D 110 (2024) 124047Subjects: General Relativity and Quantum Cosmology (gr-qc); Fluid Dynamics (physics.flu-dyn)
We investigate perturbations in a rotational and incompressible fluid flow. Interested in the phenomenon analogous to the black hole ergoregion instability, we verify the influence of the vorticity in the instability associated with this fluid system, in the presence of a region in which the fluid flow velocity is greater than the speed of the perturbation. With this aim, we compute the quasinormal modes of the system, using two different numerical methods, obtaining an excellent numerical agreement between them. We find that the vorticity tends to diminish the ergoregion instability of the system.
- [25] arXiv:2412.19030 (replaced) [pdf, html, other]
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Title: Inflationary observables in $F(R)$ gravitySubjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)
We present phenomenological signatures for a modified gravity model f(R), constructed with linear, quadratic, cubic and quartic terms. The obtained signatures satisfy current phenomenological bounds reported by PLANCK and BICEP3. Furthermore, two of the model solutions $\sigma_1$ and $\sigma_2$ seem to favor a much lower value for the tensor-to-scalar ratio $0.0005<r_{\sigma_1}<0.0015$ and $r_{\sigma_2}<0.00015$ than the current reported experimental bounds. The results we obtained are quantitatively similar to those presented in previous studies for $R^3$ models.
- [26] arXiv:2404.14045 (replaced) [pdf, html, other]
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Title: Defining the type IIB matrix model without breaking Lorentz symmetryComments: 6 pages, 1 figure, (v3) The version accepted for publication in Physical Review LettersSubjects: High Energy Physics - Theory (hep-th); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Lattice (hep-lat)
The type IIB matrix model is a promising nonperturbative formulation of superstring theory, which may elucidate the emergence of (3+1)-dimensional space-time. However, the partition function is divergent due to the Lorentz symmetry, which is represented by a noncompact group. This divergence has been regularized conventionally by introducing some infrared cutoff, which breaks the Lorentz symmetry. Here we point out that Lorentz invariant observables become classical as one removes the infrared cutoff and that this "classicalization" is actually an artifact of the Lorentz symmetry breaking cutoff. In order to overcome this problem, we propose a natural way to "gauge-fix" the Lorentz symmetry in a fully nonperturbative manner. This also enables us to perform numerical simulations in such a way that the time-evolution can be extracted directly from the matrix configurations.
- [27] arXiv:2407.02567 (replaced) [pdf, html, other]
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Title: Local Description of Decoherence of Quantum Superpositions by Black Holes and Other BodiesComments: 16 pages, 1 figure. v2: Added clarifying remarks. v3: Minor editorial changes, fixed a typo in Eq. (4.4). Version published in Phys. Rev. DJournal-ref: Phys. Rev. D 111, 025014 (2025)Subjects: High Energy Physics - Theory (hep-th); General Relativity and Quantum Cosmology (gr-qc); Quantum Physics (quant-ph)
It was previously shown that if an experimenter, Alice, puts a massive or charged body in a quantum spatial superposition, then the presence of a black hole (or more generally any Killing horizon) will eventually decohere the superposition [arXiv:2205.06279, arXiv:2301.00026, arXiv:2311.11461]. This decoherence was identified as resulting from the radiation of soft photons/gravitons through the horizon, thus suggesting that the global structure of the spacetime is essential for describing the decoherence. In this paper, we show that the decoherence can alternatively be described in terms of the local two-point function of the quantum field within Alice's lab, without any direct reference to the horizon. From this point of view, the decoherence of Alice's superposition in the presence of a black hole arises from the extremely low frequency Hawking quanta present in Alice's lab. We explicitly calculate the decoherence occurring in Schwarzschild spacetime in the Unruh vacuum from the local viewpoint. We then use this viewpoint to elucidate (i) the differences in decoherence effects that would occur in Schwarzschild spacetime in the Boulware and Hartle-Hawking vacua; (ii) the difference in decoherence effects that would occur in Minkowski spacetime filled with a thermal bath as compared with Schwarzschild spacetime; (iii) the lack of decoherence in the spacetime of a static star even though the vacuum state outside the star is similar in many respects to the Boulware vacuum around a black hole; and (iv) the requirements on the degrees of freedom of a material body needed to produce a decoherence effect that mimics that of a black hole.
- [28] arXiv:2407.09595 (replaced) [pdf, html, other]
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Title: A non-local way around the no-global-symmetries conjecture in quantum gravity?Comments: v3: 14 pages; equations (3) and (6) of v1 corrected; published versionJournal-ref: Class. Quantum Grav. (2025) 42 037001Subjects: High Energy Physics - Theory (hep-th); General Relativity and Quantum Cosmology (gr-qc)
The no-global-symmetries conjecture is central to the swampland program that delineates the boundary between effective field theories that can be obtained from a quantum theory of gravity to those that cannot. The conjecture states that virtual black-hole configurations in the path integral generate terms that violate all global symmetries in the effective action for matter. Because of its central role, it is crucial to understand limitations to the validity of this conjecture. In the context of the Lorentzian path integral over spacetime geometries, we explore whether virtual black-hole configurations can be suppressed dynamically. To that end, we work in a spherically symmetric setting and make use of horizon-detecting curvature invariants which vanish on the horizon. By constructing a non-local gravitational action from the inverse of such curvature invariants, we can achieve destructive interference of black-hole configurations in the path integral. Given that non-local gravitational actions appear generically as the result of integrating out matter degrees of freedom from a theory for quantum gravity and matter, our exemplary construction reinforces discussions about the role of non-locality in assessing arguably universal properties of quantum gravity within the framework of path integrals.
- [29] arXiv:2409.12898 (replaced) [pdf, html, other]
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Title: On the classical limit of the (sub)$^{n}$-leading soft graviton theorems in $D = 4$ without deflectionComments: v3: 37 pages, 1 figure, presentation improved, matched with the published versionJournal-ref: JHEP 12(2024) 207Subjects: High Energy Physics - Theory (hep-th); General Relativity and Quantum Cosmology (gr-qc)
Tree-level gravitational amplitudes satisfy an infinite hierarchy of soft factorization theorems. The existence of these theorems has been recently linked with the existence of an infinite tower of asymptotic symmetries. In this paper, we analyze the relevance of the soft graviton theorems beyond sub-leading order in the context of classical gravitational scattering in four dimensions. More in detail, we show that the infinite impact parameter limit of the late-time gravitational field emitted during a classical scattering can be derived using these factorization theorems. The classical field obtained in this (infinite impact parameter) regime has an expansion in the frequency of the detector where the modes scale as $\omega^{n}\log{\omega}$ with a vanishing memory.
- [30] arXiv:2410.15562 (replaced) [pdf, html, other]
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Title: Galactic and extragalactic probe of dark matter with LISA's binary black holesComments: 13 pages, 7 figures. To appear in JCAPSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA); General Relativity and Quantum Cosmology (gr-qc)
The upcoming LISA mission will be able to detect gravitational waves from galactic and extragalactic compact binaries. Here, we report on LISA's capability to probe dark matter around these binaries if the latter constitute black holes. By analyzing the variation in the chirp mass of the binary, we show that depending on the black hole masses, LISA should be able to probe their surrounding dark matter to a luminosity distance of $\approx 1$ Gpc if such binaries are observed within the inner $\approx 10$ pc of their galactic center for particle-like dark matter or near the galactic solitonic core for wave-like dark matter. In the case a null result is recorded during the course of observation of \emph{well-localized} binaries, one can still rule out certain parameter spaces of dark matter as being the dominant contributor to the matter budget of the Universe.
- [31] arXiv:2410.18257 (replaced) [pdf, html, other]
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Title: $\text{T}\overline{\text{T}}$ deformations from AdS$_2$ to dS$_2$Comments: 35 pages + appendices, 11 figures; v2: references added, JHEP versionSubjects: High Energy Physics - Theory (hep-th); General Relativity and Quantum Cosmology (gr-qc)
We revisit the formalism of $\text{T}\overline{\text{T}}$ deformations for quantum theories that are holographically dual to two-dimensional dilaton-gravity theories with Dirichlet boundary conditions. To better understand the microscopics of de Sitter space, we focus on deformations for which the dual bulk geometry flows from Anti-de Sitter to de Sitter space. We explore two distinct ways to achieve this: either through so-called centaur geometries that interpolate between AdS$_2$ and dS$_2$, or by a spherical dimensional reduction of $\text{T}\overline{\text{T}} + \Lambda_2$ theories that were proposed to give a microscopic interpretation of three-dimensional de Sitter entropy. We derive the microscopic energy spectrum, heat capacities, and deformed Cardy expressions for the thermodynamic entropy in the canonical and microcanonical ensembles for these two setups. In both setups a signature of the change from AdS to dS is that the heat capacity at a fixed deformation parameter of the boundary system changes sign, indicating the existence of a thermodynamically unstable de Sitter patch. Our findings provide important consistency conditions for holographic models of the dS$_2$ static patch.
- [32] arXiv:2410.23342 (replaced) [pdf, html, other]
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Title: Double Copy in AdS3 from Minitwistor SpaceComments: 41 pages + appendices; v3: improved discussion in Section 7Subjects: High Energy Physics - Theory (hep-th); General Relativity and Quantum Cosmology (gr-qc)
The double copy relates gravitational theories to the square of gauge theories. While it is well understood in flat backgrounds, its precise realisation around curved spacetimes remains an open question. In this paper, we construct a classical double copy for cohomology class representatives in the minitwistor space of hyperbolic spacetimes. We find that the realisation of a physical double copy requires that the masses of the different spinning fields are not equal, contrary to the flat space prescription. This leads to a position-space double copy for bulk-to-boundary propagators. We also show that in coordinate space, this implies the Cotton double copy for waves and warped black holes of Topologically Massive Gravity. We show that these are exact double copy relations by constructing their Kerr-Schild metrics and also analysing the Kerr-Schild double copy. Furthermore, we find that near the boundary the double copy relates the dual CFT currents.
- [33] arXiv:2411.06951 (replaced) [pdf, html, other]
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Title: Some aspects of QFT in non-inertial framesComments: 23 pages LateXSubjects: High Energy Physics - Theory (hep-th); General Relativity and Quantum Cosmology (gr-qc)
Some aspects of quantum field theory in a general (i.e. non inertial) frame of Minkowski spacetime are studied. Conditions for the presence of horizons as well as for the change in the definition of positive energy solutions are examined. It is found that none of these phenomena is generic. This means that in the general case there is no natural way to define positive frequencies, which is the standard road to define particles. In that sense, (as well as in others) non inertial frames are similar to curved spacetimes.
- [34] arXiv:2501.03364 (replaced) [pdf, html, other]
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Title: Lindblad estimation with fast and precise quantum controlComments: 6 figures, 22 pages (main text: 16 pages, appendices: 6 pages)Subjects: Quantum Physics (quant-ph); General Relativity and Quantum Cosmology (gr-qc)
Enhancing precision sensors for stochastic signals using quantum techniques is a promising emerging field of physics. Estimating a weak stochastic waveform is the core task of many fundamental physics experiments including searches for stochastic gravitational waves, quantum gravity, and axionic dark matter. Simultaneously, noise spectroscopy and characterisation, e.g. estimation of various decay mechanisms in quantum devices, is relevant to a broad range of fundamental and technological applications. We consider the ultimate limit on the sensitivity of these devices for Lindblad estimation given any quantum state, fast and precise control sequence, and measurement scheme. We show that it is optimal to rapidly projectively measure and re-initialise the quantum state. We develop optimal protocols for a wide range of applications including stochastic waveform estimation, spectroscopy with qubits, and Lindblad estimation.