Latest in gr-qc

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Aspects of AdS$_2$ classification in M-theory: Solutions with mesonic and baryonic chargesAug 22 2019We construct necessary and sufficient geometric conditions for AdS$_2$ solutions of M-theory with, at least, minimal supersymmetry to exist. We generalize previous results in the literature for ${\cal N}=(2,0)$ supersymmetry in AdS$_2$ to ${\cal N}=(1,0)$. ... More
Measuring $H_0$ in PTA with gravitational wavesAug 22 2019Pulsar Timing Arrays have yet to find convincing evidence of gravitational waves. Some time ago it was pointed out by one of the authors that a dramatic enhancement of the signal would take place for particular values of the angle subtended by the source ... More
From quantized spins to rotating black holesAug 22 2019It has been shown recently that classical-spin limit of minimally coupled spinning particles can reproduce the dynamics of Kerr black holes. This raises the intriguing question of how particles with finite (quantized) spins can capture the classical potential ... More
Galaxy number counts at second order: an independent approachAug 22 2019Next generation surveys will be capable of determining cosmological parameters beyond percent level.To match this precision, theoretical descriptions should look beyond the linear perturbations to approximate the observables in large scale structure. ... More
Constraints on Quasi-dilaton Massive GravityAug 22 2019The last decade has seen great advancements in the field of modified gravity, motivated by the dark energy problem, or by the search for a fundamental quantum gravity theory. With a phenomenologically-driven approach, we consider dRGT theory and its extension, ... More
The instability of a black hole with $f(R)$ global monopole under extended uncertainty principleAug 22 2019We consider the evolution of black hole involving an $f(R)$ global monopole based on the Extended Uncertainty Principle (EUP). The black hole evolutions refer to the instability due to the Parikh-Kraus-Wilczeck tunneling radiation or fragmentation. It ... More
Anisotropic neutron stars by gravitational decouplingAug 22 2019In this work we obtain an anisotropic neutron star solution by gravitational decoupling starting from a perfect fluid configuration which has been used to model the compact object PSR J0348+0432. Additionally, we consider the same solution to model the ... More
Autonomous Dynamical System of Einstein-Gauss-Bonnet CosmologiesAug 21 2019In this paper, we study the phase space of cosmological models in the context of Einstein-Gauss-Bonnet theory. More specifically, we consider a generalized dynamical system that encapsulates the main features of the theory and for the cases that this ... More
Effects of quantum corrections on the criticality and efficiency of black holes surrounded by a perfect fluidAug 21 2019We study some properties of the extended phase space of a quantum-corrected Schwarzschild black hole surrounded by a perfect fluid. In particular we demonstrate that, due to the quantum correction, there exist first and second order phase transitions ... More
Black hole evaporation and semiclassicality at large DAug 21 2019Black holes of sufficiently large initial radius are expected to be well described by a semiclassical analysis at least until half of their initial mass has evaporated away. For a small number of spacetime dimensions, this holds as long as the black hole ... More
Effective Field Theory of Gravity to All OrdersAug 21 2019We construct the general effective field theory of gravity coupled to the Standard Model of particle physics, which we name GRSMEFT. Our method allows the systematic derivation of a non-redundant set of operators of arbitrary dimension with generic field ... More
Glitching pulsars: unraveling the interactions of general relativity with quantum fields in the strong field regimesAug 21 2019We present a modification of our previous model for the mechanisms underlying the glitch phenomena in pulsars and young neutron stars. Accordingly, pulsars are born with embryonic cores comprising of purely incompressible superconducting gluon-quark superfluid ... More
Geodetic Motion Around Rotating Blackhole in Nonlocal GravityAug 21 2019Recently the non-local gravity theory has come out to be a good candidate for an effective field theory of quantum gravity and also it can provide rich phenomenology to understand late-time accelerating expansion of the universe. For any valid theory ... More
Parametrizations for tests of gravityAug 21 2019With the increasing wealth of high-quality astronomical and cosmological data and the manifold departures from General Relativity in principle conceivable, the development of generalized parametrization frameworks that unify gravitational models and cover ... More
Six-dimensional Myers-Perry rotating black hole cannot be overspunAug 21 2019Though under non-linear accretion, all black holes in four and higher dimensions obey the weak Cosmic Censorship Conjecture, however they generally violate it for the linear test particle accretion with the exception of five dimensional rotating black ... More
Casimir force in the Gödel space-time and its possible induced cosmological inhomogeneityAug 21 2019The Casimir force between two parallel plates in the G\"odel universe is computed for a scalar field at finite temperature. It is observed that when the plates separation is comparable with the scale given by the rotation of the space-time, the force ... More
The cosmological phase space of generalized hybrid metric-Palatini theories of gravityAug 21 2019In this work, we study the cosmological phase space of the generalized hybrid metric-Palatini gravity theory, characterized by the functions $f\left(R,\mathcal R\right)$, using a dynamical system approach. We formulate the propagation equations of the ... More
Charged accelerating AdS black hole of $f(r)$ gravity and the Joule-Thomson expansionAug 21 2019In this paper, the thermodynamical properties and the phase transitions of the charged accelerating anti-de Sitter (AdS) black holes are investigated in the framework of the $f(r)$ gravity. By studying the conditions for the phase transitions, it has ... More
Inflationary Phenomenology of Einstein Gauss-Bonnet Gravity Compatible with GW170817Aug 20 2019In this work we shall study Einstein Gauss-Bonnet theories and we investigate when these can have their gravitational wave speed equal to the speed of light, which is unity in natural units, thus becoming compatible with the striking event GW170817. We ... More
Some physical implications of regularization ambiguities in SU(2) gauge-invariant loop quantum cosmologyAug 20 2019The way physics of loop quantum gravity is affected by the underlying quantization ambiguities is an open question. We address this issue in the context of loop quantum cosmology using gauge-covariant fluxes. Consequences are explored for two choices ... More
Gravitational memory in the bulkAug 20 2019A method for detecting gravitational memory is proposed. It makes use of ingoing null geodesics instead of timelike geodesics in the original formulation by Christodoulou. It is argued that the method is applicable in the bulk of a spacetime. In addition, ... More
Quasi-local conserved charges in General RelativityAug 20 2019A general prescription for constructing quasi-local conserved quantities in General Relativity is proposed. The construction is applied to BMS symmetry generators in Newman-Unti gauge, so as to define quasi-local BMS charges. It is argued that the zero ... More
On polarized scattering equations for superamplitudes of 11D supergravity and ambitwistor superstringAug 20 2019We revisited the formalism of 11D polarized scattering equation by Geyer and Mason from the perspective of spinor frame approach and spinor moving frame formulation of the 11D ambitwistor superstring action. In particular, we rigorously obtain the equation ... More
Black holes in Sol minoreAug 20 2019We consider black holes in five-dimensional $N=2$ $\text{U}(1)$-gauged supergravity coupled to vector multiplets, with horizons that are homogeneous but not isotropic. We write down the equations of motion for electric and magnetic ans\"atze, and solve ... More
Second-order self-force calculation of gravitational binding energyAug 20 2019Self-force theory is the leading method of modeling extreme-mass-ratio inspirals (EMRIs), key sources for the gravitational-wave detector LISA. It is well known that for an accurate EMRI model, {\em second-order} self-force effects are critical, but calculations ... More
Noncommutativity and the Weak Cosmic CensorshipAug 20 2019We show that a noncommutative massless scalar probe can dress a naked singularity in $AdS_3$ spacetime, consistent with the weak cosmic censorship. The dressing occurs at high energies, which is typical at the Planck scale. Using a noncommutative duality, ... More
Models of light-like charges with non-geodesic world linesAug 20 2019Massless particles in General Relativity move with the speed of light, their trajectories in spacetime are described by null geodesics. This is independent of the electrical charge of the particle being considered, however, the charged light-like case ... More
Force-free electrodynamics near rotation axis of a Kerr black holeAug 20 2019Despite their potential importance for understanding astrophysical jets, physically realistic exact solutions for magnetospheres around Kerr black holes have not been found, even in the force-free approximation. Instead approximate analytical solutions ... More
Bounding f(R,T) gravity by particle creationAug 20 2019We consider the possibility of the quantum vacuum states in f(R,T) gravity. Particularly, we study the Bogoliubov transformations associated to different vacuum states for some f(R,T) models. The method consists of fixing the f(R,T) free parameters by ... More
Profiled spectral lines of Keplerian rings orbiting in the regular Bardeen black hole spacetimesAug 20 2019Considering the regular Bardeen black hole spacetimes, we test the observational effects of the general relativistic solutions coupled to non-linear electrodynamics (NED) by studying the photon motion in the effective geometry governed by the spacetime ... More
Timelike geodesics in Naked Singularity and Black Hole SpacetimesAug 20 2019In this paper, we derive the solutions of orbit equations for a class of naked singularity spacetimes, and compare these with timelike orbits, that is, particle trajectories in the Schwarzschild black hole spacetime. The Schwarzschild and naked singularity ... More
Modified Gravity Theories in Light of the Anomalous Velocity Dispersion of NGC1052-DF2Aug 20 2019Recent observations of ultra-dwarf galaxy NGC1052-DF2 started an interesting discussion between dark matter hypothesis and modified gravity theories. Reported low velocity dispersion (< 10.5 km/s at 90% confidence level) derived from the kinematic data ... More
Parameterized and Consistency Tests of Gravity with Gravitational Waves: Current and FutureAug 19 2019Gravitational wave observations offer unique opportunities to probe gravity in the strong and dynamical regime, which was difficult to access previously. We here review two theory-agnostic ways to carry out tests of general relativity with gravitational ... More
Improved Constraints on Modified Gravity with Eccentric Gravitational WavesAug 19 2019Recent gravitational wave observations have allowed stringent new constraints on modifications to General Relativity (GR) in the extreme gravity regime. Although these observations were consistent with compact binaries with no orbital eccentricity, gravitational ... More
Electrodynamics of tilted Dirac/Weyl materials: A unique platform for unusual surface plasmon polaritonsAug 19 2019The electrodynamics of Weyl semimetals (WSMs) is an extension of Maxwell's theory where in addition to field strength tensor $F_{\mu\nu}$, an axion field enters the theory which is parameterized by a four-vector $b^\mu=(b_0,\bf b)$. In the tilted Weyl ... More
Inflation in supergravity from field redefinitionsAug 19 2019Supergravity (SUGRA) theories are specified by a few functions, most notably the real K\"ahler function denoted by $G(T_i, \bar {T}_i) = K + \log |W|^2$, where K is a real K\"ahler potential, and W is a holomorphic superpotential. A field redefinition ... More
Upgraded antennas for pulsar observations in the Argentine Institute of Radio astronomyAug 19 2019The Argentine Institute of Radio astronomy (IAR) is equipped with two single-dish 30mts radio antennas capable of performing daily observations of pulsars and radio transients in the southern hemisphere at 1.4 GHz. We aim to introduce to the international ... More
Pattern of perturbations from a coherent quantum inflationary horizonAug 19 2019It is proposed that a coherent quantum inflationary horizon produces relic primordial curvature perturbations with a distinctive pattern of nonlocal correlations. A holographic quantum model is used to derive an uncertainty for space-time localization ... More
New Loop Quantum Cosmology Modifications from Gauge-covariant FluxesAug 19 2019Loop quantum cosmology is a symmetry reduced quantization of cosmological spacetimes based on loop quantum gravity. While it has been succsessful in resolution of various cosmological singularities and connecting Planck scale physics to phenomenology, ... More
Oscillating scalar fields and the Hubble tension: a resolution with novel signaturesAug 19 2019We present a detailed investigation of a sub-dominant oscillating scalar field ('early dark energy', EDE) in the context of resolving the Hubble tension. Consistent with earlier work, but without relying on fluid approximations, we find that a scalar ... More
The Speed of Quantum Information Spreading in Chaotic SystemsAug 19 2019We present a general theory of quantum information propagation in chaotic quantum many-body systems. The generic expectation in such systems is that quantum information does not propagate in localized form; instead, it tends to spread out and scramble ... More
Origin of ultra-light fields during inflation and their suppressed non-GaussianityAug 19 2019We study the structure of multi-field inflation models where the primordial curvature perturbation is able to vigorously interact with an ultra-light isocurvature field -- a massless fluctuation orthogonal to the background inflationary trajectory in ... More
Post-Newtonian Hamiltonian description of an atom in a weak gravitational fieldAug 19 2019We extend the systematic calculation of an approximately relativistic Hamiltonian for centre of mass and internal dynamics of an electromagnetically bound two-particle system by Sonnleitner and Barnett [1] to the case including a weak post-Newtonian gravitational ... More
Charged Taub-NUT solution in Lovelock gravity with generalized Wheeler polynomialsAug 19 2019Wheeler's approach to finding exact solutions in Lovelock gravity has been predominantly applied to static spacetimes. This has led to a Birkhoff's theorem for arbitrary base manifolds in dimensions higher than four. In this work, we generalize the method ... More
Finite spectral triples for the fuzzy torusAug 19 2019Finite real spectral triples are defined to characterise the non-commutative geometry of a fuzzy torus. The geometries are the non-commutative analogues of flat tori with moduli determined by integer parameters. Each of these geometries has four different ... More
Local description of S-matrix in quantum field theory in curved spacetime using Riemann-normal coordinateAug 19 2019Success of S-matrix in quantum field theory in Minkowski spacetime naturally leads to the question of construction of S-matrix in a general curved spacetime. It is known that a global description of S-matrix may not exist in an arbitrary curved spacetime. ... More
GB holographic superconductors in exponential nonlinear electrodynamicsAug 19 2019The low-energy limits of the string theory lead to the higher-order curvature corrections for Einstein gravity. Also, they give the higher-order derivative corrections for the Maxwell or linear electrodynamics, which suggests the nonlinear electrodynamics. ... More
Scalar field effects on the orbit of S2 starAug 19 2019Precise measurements of the S-stars orbiting SgrA* have set strong constraints on the nature of the compact object at the centre of the Milky Way. The presence of a black hole in that region is well established, but its neighboring environment is still ... More
Emergent metric and geodesic analysis in cosmological solutions of (torsion-free) Polynomial Affine GravityAug 19 2019Starting from an affinely connected space, we consider a model of gravity whose fundamental field is the connection. We build up the action using as sole premise the invariance under diffeomorphisms, and study the consequences of a cosmological ansatz ... More
Nonlinear matter terms in general scalar-tensor braneworld cosmologyAug 19 2019A five dimensional braneworld cosmological model in general scalar-tensor action comprises of various Horndeski Lagrangian is considered. The Friedmann equations in the case of the strongly and weakly coupled $\mathcal{L}_5$ Horndeski Lagrangian have ... More
Spinning and Spinning Deviation Equations of Bi-metric Type TheoriesAug 18 2019Spinning equations of bi-metric types theories of gravity, the counterpart of the Papapetrou spinning equations of motion have been derived as well as their corresponding spinning deviation equations. Due to introducing different types of bi-metric theories, ... More
Slowly rotating Bose-Einstein Condensate confronted with the rotation curves of 12 dwarf galaxiesAug 18 2019We assemble a database of 12 dwarf galaxies, for which optical (R-band) and near-infrared ($3.6\mu m$) surface brightness density together with spectroscopic rotation curve data are available, in order to test the slowly rotating Bose-Einstein Condensate ... More
The Particle and Energy Cost of Entanglement of Hawking Radiation with the Final Vacuum StateAug 18 2019A semiclassical analysis shows that in the process of black hole formation and evaporation, an initial pure state will evolve to a mixed state, i.e., information will be lost. One way of avoiding this conclusion without invoking drastic modifications ... More
An overview of quasinormal modes in modified and extended gravityAug 17 2019As gravitational waves are now being nearly routinely measured with interferometers, the question of using them to probe new physics becomes increasingly legitimate. In this article, we rely on a well established framework to investigate how the complex ... More
Lightcone OPE in a CFT with lowest twist scalar primaryAug 17 2019We study the operator product expansion (OPE) of two identical scalar primary operators in the lightcone limit in a conformal field theory where a scalar is the operator with lowest twist. We see that in CFTs where both the stress tensor and a scalar ... More
Rotating and non-rotating AdS black holes in $f({\cal T})$ gravity non-linear electrodynamicsAug 17 2019We derive new exact charged $d$-dimensional black hole solutions for quadratic teleparallel equivalent gravity, $f({\cal T})=a_0+a_1{\cal T}+a_2{\cal T}^2$, where $\cal T$ is the torsion scalar, in the case of non-linear electrodynamics. We give a specific ... More
Higgs inflation in complex geometrical scalar-tensor theory of gravityAug 17 2019We derive a Higgs inflationary model in the context of a complex geometrical scalar-tensor theory of gravity. In this model the Higgs inflaton scalar field has geometrical origin playing the role of the Weyl scalar field in the original non-riemannian ... More
Summary of cosmology with gravitational waves from compact binary coalescencesAug 16 2019GW170817 with its coincident optical counterpart has led to a first "standard siren" measurement of the Hubble constant independent of the cosmological distance ladder. The Schutz "statistical" method, which is expected to work in the absence of uniquely ... More
Superradiant instability of charged scalar fields in higher-dimensional Reissner-Nordström-de Sitter black holesAug 16 2019Black holes possess trapping regions which lead to intriguing dynamical effects. By properly scattering test fields off a black hole, one can extract energy from it, leading to the growth of the amplitude of the test field in expense of the black hole's ... More
Gravitational waves, CMB polarization, and the Hubble tensionAug 16 2019The discrepancy between the Hubble parameter inferred from local measurements and that from the cosmic microwave background (CMB) has motivated careful scrutiny of the assumptions that enter both analyses. Here we point out that the location of the recombination ... More
QCD Axion on Hilltop by Phase Shift of $π$Aug 16 2019We show that the initial misalignment angle of the QCD axion (or axion-like particles) can be set very close to $\pi$, if the QCD axion has a mixing with another heavy axion which induces the phase shift $\approx \pi$ after inflation. In the simplest ... More
Graviton Propagator in a 2-Parameter Family of de Sitter Breaking GaugesAug 16 2019We formulate the graviton propagator on de Sitter background in a 2-parameter family of simple gauges which break de Sitter invariance. Explicit results are derived for the first order perturbations in each parameter. These results should be useful in ... More
A gravitational-wave measurement of the Hubble constant following the second observing run of Advanced LIGO and VirgoAug 16 2019This paper presents the gravitational-wave measurement of the Hubble constant $H_0$ using the detections from the first and second observing runs of the Advanced LIGO and Virgo detector network. The presence of the transient electromagnetic counterpart ... More
A gravitational-wave measurement of the Hubble constant following the second observing run of Advanced LIGO and VirgoAug 16 2019Aug 21 2019This paper presents the gravitational-wave measurement of the Hubble constant $H_0$ using the detections from the first and second observing runs of the Advanced LIGO and Virgo detector network. The presence of the transient electromagnetic counterpart ... More
Cosmological Inference using Gravitational Wave Standard Sirens: A Mock Data ChallengeAug 16 2019The detection of gravitational waves from the binary neutron star merger GW170817 alongside its optical counterparts, marked the beginning of gravitational wave cosmology as it allowed for the first constraint onthe Hubble constant $H_0$ using gravitational ... More
Cosmological Inference using Gravitational Wave Standard Sirens: A Mock Data ChallengeAug 16 2019Aug 19 2019The detection of gravitational waves from the binary neutron star merger GW170817, alongside its optical counterpart, marked the beginning of gravitational wave cosmology as it allowed for the first constraint on the Hubble constant $H_0$ using gravitational ... More
On the gravitational entropy of accelerating black holesAug 16 2019In this paper we have examined the validity of a proposed definition of gravitational entropy in the context of accelerating black hole solutions of the Einstein field equations, which represent the realistic black hole solutions. We have adopted a phenomenological ... More
Slicing conditions for axisymmetric gravitational collapse of Brill wavesAug 16 2019In numerical relativity, spacetimes involving compact strongly gravitating objects are constructed as numerical solutions of Einstein's equations. Success of such a process strongly depends on the availability of appropriate coordinates, which are typically ... More
Astrophysics and cosmology with a deci-hertz gravitational-wave detector: TianGOAug 16 2019We present the astrophysical science case for a space-based, deci-Hz gravitational-wave (GW) detector. We particularly highlight an ability in inferring a source's sky location, both when combined with a network of ground-based detectors to form a long ... More
Cosmological Relaxation of Higgs Mass Before and After LHC and NaturalnessAug 16 2019In post LHC era the old idea of cosmological vacuum relaxation of the Higgs mass that does not require any new physics in the vicinity of LHC energies acquires a new meaning. I discuss how this concept of naturanless differs from the standard one by 't ... More
Critical phenomena in gravitational collapse with two competing massless matter fieldsAug 16 2019In the gravitational collapse of matter beyond spherical symmetry, gravitational waves are necessarily present. On the other hand, gravitational waves can collapse to a black hole even without matter. One might therefore wonder whether the interaction ... More
Quantum geometry from higher gauge theoryAug 16 2019Higher gauge theories play a prominent role in the construction of 4d topological invariants and have been long ago proposed as a tool for 4d quantum gravity. The Yetter lattice model and its continuum counterpart, the BFCG theory, generalize BF theory ... More
Taub-NUT from the Dirac monopoleAug 16 2019Writing the metric of an asymptotically flat spacetime in Bondi coordinates provides an elegant way of formulating the Einstein equation as a characteristic value problem. In this setting, we find that a specific class of asymptotically flat spacetimes, ... More
Design and experimental demonstration of a laser modulation system for future gravitational-wave detectorsAug 16 2019Detuning the signal-recycling cavity length from a cavity resonance significantly improves the quantum noise beyond the standard quantum limit, while there is no km-scale gravitational-wave detector successfully implemented the technique. The detuning ... More
Ascertaining the cosmological constant using galactic superclusters in $f(R,T)$ gravityAug 16 2019In this work we estimated the cosmological constant in a pioneering approach by using galactic superclusters in the layout of $f(R,T)$ gravity. We set $f(R,T) = R + 2\lambda T$ where $\lambda$ is the model parameter. We report that appropriate values ... More
Probing Massive Black Hole Binary Populations with LISAAug 15 2019ESA and NASA are moving forward with plans to launch LISA around 2034. With data from the Illustris cosmological simulation, we provide analysis of LISA detection rates accompanied by characterization of the merging massive black hole population. Massive ... More
Perspectives on the dynamics in loop effective black hole interiorAug 15 2019In the loop quantum gravity context, there have been numerous proposals to quantize the reduced phase space of a black hole, and develop a classical effective description for its interior which eventually resolves the singularity. However little progress ... More
Spacetime and Universal Soft Modes --- Black Holes and BeyondAug 15 2019Recently, a coherent picture of the quantum mechanics of an evaporating black hole has been presented which reconciles unitarity with the predictions of the equivalence principle. The thermal nature of a black hole as viewed in a distance reference frame ... More
The two-harmonic approximation for gravitational waveforms from precessing binariesAug 15 2019Binary-black-hole orbits precess when the black-hole spins are mis-aligned with the binary's orbital angular momentum. The apparently complicated dynamics can in most cases be described as simple precession of the orbital angular momentum about an approximately ... More
Inflation in generalized unimodular gravityAug 15 2019The recently suggested generalized unimodular gravity theory, which was originally put forward as a model of dark energy, can serve as a model of cosmological inflation driven by the effective perfect fluid -- the dark purely gravitational sector of the ... More
Analytic Solutions to Compact Binary Inspirals With Leading Order Spin-Orbit Contribution Using The Dynamical Renormalization GroupAug 15 2019We calculate the real-space trajectory and spin precession of a generic spinning compact binary inspiral at any time instant using the dynamical renormalization group formalism. This method leads to closed-form analytic solutions to the binary motion ... More
Einstein-Vlasov Calculations of Structure FormationAug 15 2019We study the dynamics of small inhomogeneities in an expanding universe collapsing to form bound structures using full solutions of the Einstein-Vlasov (N-body) equations. We compare these to standard Newtonian N-body solutions using quantities defined ... More
Detecting Gravitational Waves in Data with Non-Gaussian NoiseAug 15 2019Searches for gravitational waves crucially depend on exact signal processing of noisy strain data from gravitational wave detectors, which are known to exhibit significant non-Gaussian behavior. In this paper, we study two distinct non-Gaussian effects ... More
Equivalence of Gibbons-Werner method to geodesics method in the study of gravitational lensingAug 15 2019The Gibbons-Werner method where the Gauss-Bonnet theorem is applied to study the gravitational deflection angle has received much attention recently. In this paper, we study the equivalence of the Gibbons-Werner method to the standard geodesics method, ... More
The role of cosmological constant in f(R, G) gravityAug 15 2019Einstein-Hilbert action is supplemented by Gauss-Bonnet squared term, its phase-space structure is constructed and canonical quantization is performed. Resolution of a contradiction that emerges in the process, requires the presence of other fields at ... More
Ricci Subtraction for Cosmological Coleman-Weinberg PotentialsAug 15 2019We reconsider the fine-tuning problem of scalar-driven inflation arising from the need to couple the inflaton to ordinary matter in order to make reheating efficient. Quantum fluctuations of this matter induce Coleman-Weinberg corrections to the inflaton ... More
Quasi-local energy and ADM mass in pure Lovelock gravityAug 15 2019We generalize the definitions of ADM mass and quasi-local energy to pure Lovelock gravity. The quasi-local energy is renormalized using the background subtraction prescription and we consider its limit for large surfaces. We find that the the large surface ... More
Field redefinition's help in constructing non-abelian gauge theoriesAug 15 2019We study, using the example of general covariance, to what extent a would-be non-abelian extension of free field abelian gauge theory can be helped by a field redefinition; answer - not much! However, models resulting from dimensional reduction also include ... More
The physical origin of the cosmological constant: continuum limit and the analogy with the Casimir effectAug 15 2019In this paper we continue the investigations in \cite{1} concerning the origin of the cosmological constant. First of all, we generalize the results in \cite{1,2} by considering a continuum approximation for a radiation field in a cosmological background. ... More
The physical origin of the cosmological constant: continuum limit and the analogy with the Casimir effectAug 15 2019Aug 22 2019In this paper we continue the investigations in \cite{1} concerning the origin of the cosmological constant. First of all, we generalise the results in \cite{1,2} by considering a continuum approximation for a radiation field in a cosmological background. ... More
CMB sky for an off-center observer in a local void I: framework for forecastsAug 15 2019The Universe is not perfectly homogeneous, the large scale structure forms over dense regions and voids. In this paper we consider the possibility that we occupy a special position in our Universe, close to the center of a local under dense region that ... More
Emergent Gravity in a Holographic UniverseAug 15 2019This dissertation investigates thermodynamic, emergent and holographic aspects of gravity in the context of causal diamonds. We obtain a gravitational first law for causal diamonds in maximally symmetric spacetimes and argue that these diamonds are in ... More
Orbit design and thruster requirement for various constant-arm space mission concepts for gravitational-wave observationAug 15 2019In previous papers, we have addressed the issues of orbit design and thruster requirement for the constant arm versions of AMIGO (Astrodynamical Middle-frequency Interferometric Gravitational-wave Observatory) mission concept and for the constant arm ... More
Inferring prompt black-hole formation in neutron star mergers from gravitational-wave dataAug 15 2019The gravitational-wave GW170817 is associated to the inspiral phase of a binary neutron star coalescence event. The LIGO-Virgo detectors sensitivity at high frequencies was not sufficient to detect the signal corresponding to the merger and post-merger ... More
Nonlocal GravitomagnetismAug 15 2019We briefly review the current status of nonlocal gravity (NLG), which is a classical nonlocal generalization of Einstein's theory of gravitation based on a certain analogy with the nonlocal electrodynamics of media. Nonlocal gravity thus involves integro-differential ... More
Signatures of noncommutativity in bar detectors of gravitational wavesAug 15 2019The comparison between the noncommutative length scale $\sqrt{\theta}$ and the length variation $\delta L=h L$, detected in the GW detectors indicate that there is a strong possibility to detect the noncommutative structure of space in the GW detector ... More
Relativistic interpretation and cosmological signature of Milgrom's accelerationAug 15 2019We propose in this letter a relativistic coordinate independent interpretation for Milgrom's acceleration $a_{0}=1.2 \times 10^{-8} \hbox{cm/s}^{2}$ through a geometric constraint obtained from the product of the Kretschmann invariant scalar times the ... More
The NANOGrav Program for Gravitational Waves and Fundamental PhysicsAug 14 2019We describe the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) and its efforts to directly detect and study gravitational waves and other synergistic physics and astrophysics using radio timing observations of millisecond pulsars. ... More
The NANOGrav Program for Gravitational Waves and Fundamental PhysicsAug 14 2019Aug 16 2019We describe the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) and its efforts to directly detect and study gravitational waves and other synergistic physics and astrophysics using radio timing observations of millisecond pulsars. ... More
Quantum Cosmology with many fluids and the choice of cosmological timeAug 14 2019In this work we propose the quantization of a cosmological model describing the primordial universe filled with five barotropic fluids, namely: radiation, dust, vacuum, cosmic strings and domain walls. We intend to identify which fluid is best suited ... More