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  • Nonsingular black holes from charged dust collapse: A concrete mechanism to evade interior singularities in general relativity
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-10-19
    Rodrigo Maier

    In this paper, we examine the gravitational collapse of a nonrelativistic charged perfect fluid interacting with a dark energy component. Given a simple factor for the energy transfer, we obtain a nonsingular interior solution which naturally matches the Reissner–Nordström–de Sitter exterior geometry. We also show that the interacting parameter is proportional to the overall charge of the final black

    更新日期:2020-10-21
  • Role of collisional matter in the framework of extended teleparallel theory
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-10-19
    Muhammad Zeeshan; M. Zubair; Rabia Saleem

    The purpose of this work is to examine the cosmic evolution in the presence of collisional matter (CM) with and without radiations in a modified Teleparallel theory involving a generic function f(T,B) which depends on the scalar torsion T and the boundary term associated to the divergence of torsion 2∇μTμ=B. We select seven novel f(T,B) models including power law, logarithmic models and exponential

    更新日期:2020-10-21
  • Three-dimensional slowly rotating black hole in Einstein-power-Maxwell theory
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-10-19
    M. B. Tataryn; M. M. Stetsko

    A three-dimensional slowly rotating black hole solution in the presence of negative cosmological constant in the Einstein-power-Maxwell theory is studied. It is shown that in the small rotation limit, the electric field, diagonal metric function and thermodynamic properties are the same as for static case, whereas the small rotation gives in addition a nondiagonal metric function and magnetic field

    更新日期:2020-10-21
  • Effective anisotropic stresses of the relic gravitons
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-10-19
    Massimo Giovannini

    The effective anisotropic stresses induced by the scalar modes of the geometry depend on the coordinate system so that the comparison of the competing results is ultimately determined by the evolution of the pivotal variables in each particular gauge. After arguing that the only reasonable physical coordinate systems for this problem are the ones where the gauge freedom is completely fixed (like the

    更新日期:2020-10-21
  • Cosmological models with squared trace in modified gravity
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-10-14
    B. Mishra; S. K. Tripathy; Saibal Ray

    In this work, we present a few simple cosmological models under the modified theory of gravity in the particular form of f(R,𝒯)=R+2f(𝒯), where R is the Ricci Scalar and 𝒯 is the trace of the energy–momentum tensor. Two special cosmological models are studied with (i) hyperbolic scale factor and (ii) specific form of the Hubble parameter. The models are observed to predict relevant cosmological parameters

    更新日期:2020-10-21
  • Particles dynamics around time conformal quintessential Schwarzschild black hole
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-10-06
    Israr Ali Khan; Amir Sultan Khan; Saeed Islam; Farhad Ali

    In this paper, the effect of time is explored on the dynamics of neutral and charged particles around the Schwarzschild (Sch) black hole (BH) environed by quintessence. We introduce a general time conformal factor e𝜖g(t) to the quintessential Sch spacetime, where g(t) is a time (t)-dependent function and 𝜖, a small parameter, that causes perturbation in the corresponding spacetime. The Noether symmetry

    更新日期:2020-10-21
  • ℋolographic 𝒩aturalness
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-09-11
    Andrea Addazi

    The ℋolographic 𝒩aturalness (ℋ𝒩) is a new paradigm towards an explanation of the Cosmological Constant (CC) and the Higgs Hierarchy (HH) in the Universe. Motivated by the Holographic Principle, and inspired by the (A)dS/CFT correspondence, we elaborate on the possibility and on the cosmological consequences of a fundamental intrinsic disorder and temperature in vacuo. We postulate that the zero vacuum

    更新日期:2020-10-21
  • Lorentzian quintessential inflation
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-08-12
    David Benisty; Eduardo I. Guendelman

    From the assumption that the slow-roll parameter 𝜖 has a Lorentzian form as a function of the e-folds number N, a successful model of a quintessential inflation is obtained. The form corresponds to the vacuum energy both in the inflationary and in the dark energy epochs. The form satisfies the condition to climb from small values of 𝜖 to 1 at the end of the inflationary epoch. At the late universe

    更新日期:2020-10-21
  • Inflation of universe by nonlinear electrodynamics
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-10-14
    S. I. Kruglov

    Nonlinear electrodynamics with two-dimensional parameters is studied. The range of electromagnetic fields, when principles of causality, unitarity and the classical stability hold, are obtained. A singularity of the electric field at the center of charges is absent within our model and there are corrections to the Coulomb law as r→∞. The universe inflation takes place in the background of stochastic

    更新日期:2020-10-17
  • A model-independent constraint on the Hubble constant with gravitational waves from the Einstein Telescope
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-10-14
    Sixuan Zhang; Shuo Cao; Jia Zhang; Tonghua Liu; Yuting Liu; Shuaibo Geng; Yujie Lian

    In this paper, we investigate the expected constraints on the Hubble constant from the gravitational-wave standard sirens, in a cosmological-model-independent way. In the framework of the well-known Hubble law, the GW signal from each detected binary merger in the local universe (z<0.10) provides a measurement of luminosity distance DL and thus the Hubble constant H0. Focusing on the simulated data

    更新日期:2020-10-17
  • Three puzzles in cosmology
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-10-13
    Samir D. Mathur

    Cosmology presents us with several puzzles that are related to the fundamental structure of quantum theory. We discuss three such puzzles, linking them to effects that arise in black hole physics. We speculate that puzzles in cosmology may be resolved by the vecro structure of the vacuum that resolves the information paradox and the “bags of gold” problem for black holes.

    更新日期:2020-10-15
  • Effects of Gauss–Bonnet entropy on thermodynamics of Kiselev black hole
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-10-13
    Abdul Jawad; Iqra Siddique; Iarley P. Lobo; Wardat us Salam

    In this paper, the thermodynamics of Reissner–Nordström-anti de Sitter black hole surrounded by quintessence is studied and the impact of the Gauss–Bonnet term is measured. The modified entropy, first law of thermodynamics and corresponding Smarr relation are derived due to the combined action of the Gauss–Bonnet term and quintessence fluid. We study the so-called black hole chemistry from the analysis

    更新日期:2020-10-15
  • Vacuum bosonic currents induced by a compactified cosmic string in dS background
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-10-13
    E. A. F. Bragança; E. R. Bezerra de Mello; A. Mohammadi

    In this paper, we study the vacuum bosonic currents in the geometry of a compactified cosmic string in the background of the de Sitter spacetime. The currents are induced by magnetic fluxes, one running along the cosmic string and another one enclosed by the compact dimension. To develop the analysis, we obtain the complete set of normalized bosonic wave functions obeying a quasiperiodicity condition

    更新日期:2020-10-15
  • A black hole inside dark matter and the rotation curves of galaxies
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-10-13
    Fateen Haddad; Nidal Haddad

    In this paper, we find a four-dimensional metric for a large black hole immersed in dark matter. Specifically, we look for and find a static spherically symmetric black hole solution to the Einstein equations which gives, in the Newtonian limit, the rotation curves of galaxies, including the flat region and the baryonic Tully–Fisher relation, and which has a regular horizon. We obtain as well the energy–momentum

    更新日期:2020-10-15
  • Two-dimensional area and matter flux in the theory of causal fermion systems
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-10-01
    Erik Curiel; Felix Finster; José M. Isidro

    The notions of two-dimensional area, Killing fields and matter flux are introduced in the setting of causal fermion systems. It is shown that for critical points of the causal action, the area change of two-dimensional surfaces under a Killing flow in null directions is proportional to the matter flux through these surfaces. This relation generalizes an equation in classical general relativity due

    更新日期:2020-10-02
  • Predictivity lost, predictivity regained: A Miltonian cosmic censorship conjecture
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-09-29
    Roberto Emparan

    Cosmic censorship is known to fail in some well-controlled phenomena, calling into question the predictive power of General Relativity and opening up the possibility of observing Planck-scale physics. We propose that the cosmic censorship conjecture can be amended so that its spirit prevails. Naked singularities that, classically, have zero mass are allowed. Physically, these are Planck-sized “black

    更新日期:2020-09-29
  • Transients from initial conditions based on Lagrangian perturbation theory in N-body simulations III: The case of Gadget-2 code
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-09-29
    Takayuki Tatekawa

    In modern cosmology, the precision of the theoretical prediction is increasingly required. In cosmological N-body simulations, the effect of higher-order Lagrangian perturbation on the initial conditions appears in terms of statistical quantities of matter density field. We have considered the effect of third-order Lagrangian perturbation theory (3LPT) on the initial conditions, which can be applied

    更新日期:2020-09-29
  • Information loss paradox revisited: Farewell firewall?
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-09-24
    Wen-Cong Gan; Fu-Wen Shu

    Unitary evolution makes pure state on one Cauchy surface evolve to pure state on another Cauchy surface. Outgoing Hawking radiation is the only subsystem on the late Cauchy surface. The requirement that Hawking radiation should be pure amounts to requiring purity of the subsystem when the total system is pure. We will see that this requirement will lead to firewall even in flat spacetime, and thus

    更新日期:2020-09-25
  • The logotropic dark fluid: Observational and thermodynamic constraints
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-09-24
    Abdulla Al Mamon; Subhajit Saha

    We have considered a spatially flat, homogeneous and isotropic FLRW universe filled with a single fluid, known as logotropic dark fluid (LDF), whose pressure evolves through a logarithmic equation-of-state. We use the recent Pantheon SNIa and cosmic chronometer datasets to constrain the parameters of this model, the present fraction of DM Ωm0 and the Hubble constant H0. We find that the mean values

    更新日期:2020-09-25
  • Testing the weak cosmic censorship conjecture in torus-like black hole under charged scalar field
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-07-25
    Wei Hong; Benrong Mu; Jun Tao

    We investigate weak cosmic censorship conjecture in charged torus-like black hole by the complex scalar field scattering. Using the relation between the conserved quantities of a black hole and the scalar field, we can calculate the change of the energy and charge within the infinitesimal time. The change of the enthalpy is connected to the change of energy, then we use those results to test whether

    更新日期:2020-09-25
  • Evolution of cosmological horizons of wormhole cosmology
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-07-28
    Sung-Won Kim

    Recently, we solved Einstein’s field equations to obtain the exact solution of the cosmological model with the Morris–Thorne-type wormhole. We found the apparent horizons and analyzed their geometric natures, including the causal structures. We also derived the Hawking temperature near the apparent cosmological horizon. In this paper, we investigate the dynamic properties of the apparent horizons under

    更新日期:2020-09-25
  • Optical properties of Einstein–Born–Infeld gravastar models in plasmas
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-08-08
    D. J. Cirilo-Lombardo; L. S. Ridao

    Gravastar models have recently been proposed as an alternative to black holes, mainly to avoid the problematic issues associated with event horizons and singularities. Recently, in [D. J. Cirilo-Lombardo and C. D. Vigh, Int. J. Mod. Phys. D28 (2019) 1950108], a regular variety of gravastar models within the context of Einstein–Born–Infeld (EBI) nonlinear electrodynamics were built. These original models

    更新日期:2020-09-25
  • Thermodynamics and reentrant phase transition for logarithmic nonlinear charged black holes in massive gravity
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-09-03
    S. Rajaee Chaloshtary; M. Kord Zangeneh; S. Hajkhalili; A. Sheykhi; S. M. Zebarjad

    We investigate a new class of (n+1)-dimensional topological black hole solutions in the context of massive gravity and in the presence of logarithmic nonlinear electrodynamics. Exploring higher-dimensional solutions in massive gravity coupled to nonlinear electrodynamics is motivated by holographic hypothesis as well as string theory. We first construct exact solutions of the field equations and then

    更新日期:2020-09-25
  • All static spherically symmetric anisotropic solutions for general relativistic polytropes
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-08-20
    G. Abellán; P. Bargueño; E. Contreras; E. Fuenmayor

    In this work, we develop an algorithm to construct all static spherically symmetric anisotropic solutions for general relativistic polytropes. To this end, we follow the strategy presented by K. Lake in Phys. Rev. D67 (2003) 104015 to obtain all static spherically symmetric perfect fluid solutions and then extended by L. Herrera el al., Phys. Rev. D77 (2008) 027502 to the interesting case of locally

    更新日期:2020-09-25
  • Nonminimal dyons with regular gravitational, electric and axion fields
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-08-20
    Alexander B. Balakin; Dmitry E. Groshev

    We consider the distribution of the axionic dark matter and the profiles of the axionically induced electric field on the background of a regular magnetic monopole. The background static spherically symmetric spacetime is considered to be regular at the center of the object; it has no event horizons, the nonminimal interaction of strong gravitational and monopole type magnetic fields being the source

    更新日期:2020-09-25
  • Generalization of the Kaiser Rocket effect in general relativity in the wide-angle galaxy 2-point correlation function
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-09-07
    Daniele Bertacca

    We study wide-angle correlations in the galaxy power spectrum in redshift space, including all general relativistic effects and the Kaiser Rocket effect in general relativity. We find that the Kaiser Rocket effect becomes important on large scales and at high redshifts, and leads to new contributions in wide-angle correlations. We believe this effect might be very important for future large volume

    更新日期:2020-09-25
  • A path(-integral) toward non-perturbative effects in Hawking radiation
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-08-08
    Pisin Chen; Misao Sasaki; Dong-han Yeom

    Hawking’s seminal discovery of black hole evaporation was based on the semi-classical, perturbative method. Whether black hole evaporation may result in the loss of information remains undetermined. The solution to this paradox would most likely rely on the knowledge of the end-life of the evaporation, which evidently must be in the non-perturbative regime. Here we reinterpret the Hawking radiation

    更新日期:2020-09-25
  • Investigating inflation driven by DBI-essence scalar field
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-09-05
    Gargee Chakraborty; Surajit Chattopadhyay

    Motivated by the work of Nojiri et al., Phys. Lett. B797, 134829 (2019), the present study demonstrates inflation driven by holographic DBI-essence scalar field. Considering a simple correction due to the Ultraviolet cutoff, we have studied the slow-roll parameters. It has been observed that the role of the UV-cutoff is not negligible and in the limiting case of ΛUV→∞ the inflationary model is characterized

    更新日期:2020-09-25
  • Nature does not play Dice at the Planck scale
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-09-19
    Tejinder P. Singh

    We start from classical general relativity coupled to matter fields. Each configuration variable and its conjugate momentum, as also spacetime points are raised to the status of matrices [equivalently operators]. These matrices obey a deterministic Lagrangian dynamics at the Planck scale. By coarse-graining this matrix dynamics over time intervals much larger than Planck time, one derives quantum theory

    更新日期:2020-09-22
  • A symmetry principle for emergent spacetime
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-09-19
    Edgar Shaghoulian

    There are many examples where geometry and gravity are concepts that emerge from a theory of quantum mechanics without gravity. This suggests thinking of gravity as an exotic phase of matter. Quantifying this phase in the Landau paradigm requires some sort of symmetry principle or order parameter that captures its appearance. In this essay, we propose higher-form symmetries as a symmetry principle

    更新日期:2020-09-22
  • Erratum: Dispersion of gravitational waves in cold spherical interstellar medium
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-09-19
    Dániel Barta; Mátyás Vasúth

    The study published in IJMPD27(4):1850040, 2018 provided a numerical result for the frequency-shift of GWs due to dispersion in interstellar medium. In order to adjust the metric functions of the originally improperly matched ‘background’ spacetime in Sec. 2.1, the authors have adopted Darmois–Israel junction conditions. In Sec. 4.1 the code used in the original paper erroneously computed the magnitude

    更新日期:2020-09-22
  • The vecro hypothesis
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-09-16
    Samir D. Mathur

    We consider three fundamental issues in quantum gravity: (a) the black hole information paradox (b) the unboundedness of entropy that can be stored inside a black hole horizon (c) the relation between the black hole horizon and the cosmological horizon. With help from the small corrections theorem, we convert each of these issues into a sharp conflict. We then argue that all three conflicts can be

    更新日期:2020-09-16
  • Demystification of nonrelativistic theories in curved background
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-09-11
    Rabin Banerjee

    We discuss a new formalism for constructing a nonrelativistic (NR) theory in curved background. Named as galilean gauge theory, it is based on gauging the global galilean symmetry. It provides a systematic algorithm for obtaining the covariant curved spacetime generalisation of any NR theory defined in flat spacetime. The resulting background is just the Newton–Cartan manifold. The example of NR free

    更新日期:2020-09-12
  • Hadamard parametrix of the Feynman Green’s function of a five-dimensional charged scalar field
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-07-13
    Visakan Balakumar; Elizabeth Winstanley

    The Hadamard parametrix is a representation of the short-distance singularity structure of the Feynman Green’s function for a quantum field on a curved spacetime background. Subtracting these divergent terms regularizes the Feynman Green’s function and enables the computation of renormalized expectation values of observables. We study the Hadamard parametrix for a charged, massive, complex scalar field

    更新日期:2020-09-11
  • Gaussian null coordinates, near-horizon geometry and conserved charges on the horizon of extremal nondilatonic black p-branes
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-08-17
    Mirjam Cvetič; Paulo J. Porfírio; Alejandro Satz

    In this paper, we examine the emergence of conserved charges on the horizon of a particular class of extremal nondilatonic black p-branes (which reduce to extremal dilatonic black holes in D=4 dimensions upon toroidal compactification) in the presence of a probe massless scalar field in the bulk. This result is achieved by writing the black p-brane geometry in a Gaussian null coordinate system which

    更新日期:2020-09-11
  • Shadows of charged rotating black holes: Kerr–Newman versus Kerr–Sen
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-08-12
    Sérgio Vinicius Monteiro C. B. Xavier; Pedro V. P. Cunha; Luís C. B. Crispino; Carlos A. R. Herdeiro

    Celebrating the centennial of its first experimental test, the theory of General Relativity (GR) has successfully and consistently passed all subsequent tests with flying colors. It is expected, however, that at certain scales new physics, in particular, in the form of quantum corrections, will emerge, changing some of the predictions of GR, which is a classical theory. In this respect, black holes

    更新日期:2020-09-11
  • Scalar radiation emitted by a source around a spherically symmetric black hole
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-07-21
    Rafael P. Bernar

    We analyze the scalar radiation emitted by a source in a circular geodesic orbit around a spherically symmetric black hole. The black hole (BH) spacetime considered is quite general, in the sense that it encompasses the solutions of Schwarzschild and Reissner–Nordström, and also the Bardeen solution of a regular BH. We use the framework of quantum field theory in curved spaces to compute the one-particle

    更新日期:2020-09-11
  • Generating solutions of Ricci-Based Gravity theories from General Relativity
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-07-07
    Emanuele Orazi

    We generalize the algorithm that establishes the correspondence between metric-affine Eddington-inspired Born-Infeld (EiBI) gravity and General Relativity (GR) to any bosonic matter sector. Along the way, a polished version of the proof of existence of a metric compatible frame associated to any metric-affine Ricci-Based Gravity (RBG) is presented. Particular attention is given to the problem of generating

    更新日期:2020-09-11
  • Role of gravity in particle physics: A unified approach
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-08-12
    Pedro D. Alvarez; Mauricio Valenzuela; Jorge Zanelli

    General Relativity (GR) and the Standard Model (SM) of particle physics are two enormously successful frameworks for our understanding the fundamental laws of nature. However, these theoretical schemes are widely disconnected, logically independent and unrelated in scope. Yet, GR and SM at some point must intersect, producing claims about phenomena that should be reconciled. Be it as it may, both schemes

    更新日期:2020-09-11
  • Stationary scalar and vector clouds around Kerr–Newman black holes
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-07-13
    Nuno M. Santos; Carlos A. R. Herdeiro

    Massive bosons in the vicinity of Kerr–Newman black holes can form pure bound states when their phase angular velocity fulfills the synchronization condition, i.e. at the threshold of superradiance. The presence of these stationary clouds at the linear level is intimately linked to the existence of Kerr black holes with synchronized hair at the nonlinear level. These configurations are very similar

    更新日期:2020-09-11
  • Tidal forces in the charged Hayward black hole spacetime
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-07-07
    Haroldo C. D. Lima Junior; Luís C. B. Crispino

    Tidal forces produced by black holes are an important result of General Relativity related to the spacetime curvature tensor. Among the astrophysical implications of tidal forces, the tidal disruption events stand out. We analyze the tidal forces in the spacetime of an electrically charged Hayward regular black hole, obtaining the components of the tidal tensor and the geodesic deviation equation.

    更新日期:2020-09-11
  • Astrophysical implications of neutron star inspiral and coalescence
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-07-13
    John L. Friedman; Nikolaos Stergioulas

    The first inspiral of two neutron stars observed in gravitational waves was remarkably close, allowing the kind of simultaneous gravitational wave and electromagnetic observation that had not been expected for several years. Their merger, followed by a gamma-ray burst and a kilonova, was observed across the spectral bands of electromagnetic telescopes. These GW and electromagnetic observations have

    更新日期:2020-09-11
  • Static black holes without spatial isometries: From AdS multipoles to electrovacuum scalarization
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-07-13
    Carlos Herdeiro; Eugen Radu

    We review recent results on the existence of static black holes (BHs) without spatial isometries in four spacetime dimensions and propose a general framework for their study. These configurations are regular on and outside a horizon of spherical topology. Two different mechanisms allowing for their existence are identified. The first one relies on the presence of a solitonic limit of the BHs; when

    更新日期:2020-09-11
  • Does gravitational radiation impact the stellar habitable zone?
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-07-25
    J. A. S. Lima; R. C. Santos; J. V. Cunha; F. E. Silva; C. E. Pellicer

    Substellar objects of ultrashort periods (less than 50 min) orbiting central stars and many ultracompact star binary systems of even smaller periods (less than 10 min) have been optically detected in the last few years. Their gravitational luminosities can be of the same order or even much greater than their electromagnetic counterparts thereby also comprising a special class of targets for the Large

    更新日期:2020-09-11
  • Analytical investigation of wave absorption by a rotating black hole analogue
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-08-05
    Leandro A. Oliveira; Carolina L. Benone; Amanda L. Almeida; Luís C. B. Crispino

    Perturbations in a draining vortex can be described analytically in terms of confluent Heun functions. In the context of analogue models of gravity in ideal fluids, we investigate analytically the absorption length of waves in a draining bathtub, a rotating black hole analogue, using confluent Heun functions. We compare our analytical results with the corresponding numerical ones, obtaining excellent

    更新日期:2020-09-11
  • Compact objects in general relativity: From Buchdahl stars to quasiblack holes
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-07-30
    José P. S. Lemos; Oleg B. Zaslavskii

    A Buchdahl star is a highly compact star for which the boundary radius R obeys R=98r+, where r+ is the gravitational radius of the star itself. A quasiblack hole is a maximum compact star, or more generically a maximum compact object, for which the boundary radius R obeys R=r+. Quasiblack holes are objects on the verge of becoming black holes. Continued gravitational collapse ends in black holes and

    更新日期:2020-09-11
  • Beyond Einstein’s General Relativity: Hybrid metric-Palatini gravity and curvature-matter couplings
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-09-09
    Tiberiu Harko; Francisco S. N. Lobo

    Einstein’s General Relativity (GR) is possibly one of the greatest intellectual achievements ever conceived by the human mind. In fact, over the last century, GR has proven to be an extremely successful theory, with a well established experimental footing, at least for weak gravitational fields. Its predictions range from the existence of black holes and gravitational radiation (now confirmed) to the

    更新日期:2020-09-10
  • The hidden scalar Lagrangians within Horndeski theory
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-09-09
    Gregory W. Horndeski

    In this paper, I show that there exists a new way to obtain scalar–tensor field theories by combining a special scalar field on the cotangent bundle with a scalar field on spacetime. These two scalar fields act as a generating function for the metric tensor. When using these two scalar fields in the Horndeski Lagrangians, we discover, while seeking Friedmann–Lemaître–Robertson–Walker-type cosmological

    更新日期:2020-09-10
  • Horizons 2020
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-09-09
    D. Grumiller; M. M. Sheikh-Jabbari; C. Zwikel

    Horizons of black holes or cosmologies are peculiar loci of spacetime, where interesting physical effects take place, some of which are probed by recent (EHT and LIGO) and future experiments (ET and LISA). We discuss that there are boundary degrees of freedom residing at the horizon. We describe their symmetries and their interactions with gravitational waves. This fits into a larger picture of boundary

    更新日期:2020-09-10
  • How black holes store information in high-order correlations
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-09-09
    Charis Anastopoulos; Konstantina Savvidou

    We explain how Hawking radiation stores significant amount of information in high-order correlations of quantum fields. This information can be retrieved by multi-time measurements on the quantum fields close to the black hole horizon. This result requires no assumptions about quantum gravity, it takes into account the differences between Gibbs’s and Boltzmann’s accounts of thermodynamics, and it clarifies

    更新日期:2020-09-10
  • You can see a clock running backwards in time
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-09-09
    M. B. Paranjape

    The epitome of a causal or anti-chronological behavior would be to see a clock running backwards in time. In this essay, we point out that this is indeed possible, but there is no problem with causality. What you see is not what is really happening. Locally, causality is always respected. However, our observation should be cause for pause to astronomers and cosmologists, who strictly observe events

    更新日期:2020-09-10
  • Magnetized cosmological model with variable deceleration parameter
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-09-09
    Sankarsan Tarai; Fakhereh Md. Esmaeili; B. Mishra; S. K. Tripathy

    In this paper, we have derived the field equations in an extended theory of gravity in an anisotropic spacetime background and in the presence of magnetic field. The physical and geometrical parameters of the models are determined with respect to the Hubble parameter using some algebraic approaches. A time varying scale factor has been introduced to analyze the behavior of the model. From some diagnostic

    更新日期:2020-09-10
  • De Sitter scalar–spinor interaction in Minkowski limit
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-09-09
    Y. Ahmadi

    The scalar–spinor interaction Lagrangian is presented by the Yukawa potential. In dS ambient space formalism, the interaction Lagrangian of scalar–spinor fields was obtained from a new transformation which is very similar to the gauge theory. The interaction of massless minimally coupled (mmc) scalar and spinor fields was investigated. The Minkowski limit of the mmc scalar field and massive spinor

    更新日期:2020-09-10
  • Will gravitational waves discover the first extra-galactic planetary system?
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-09-07
    Camilla Danielski; Nicola Tamanini

    Gravitational waves have opened a new observational window through which some of the most exotic objects in the universe, as well as some of the secrets of gravitation itself, can now be revealed. Among all these new discoveries, we recently demonstrated15 that space-based gravitational wave observations will have the potential to detect a new population of massive circumbinary exoplanets everywhere

    更新日期:2020-09-09
  • Update constraints on neutrino mass and mass hierarchy in light of dark energy models
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-09-07
    Zhenjie Liu; Haitao Miao

    Combining cosmic microwave (CMB) background data from Planck satellite data, Baryon Acoustic Oscillations (BAO) measurements and Type Ia supernovae (SNe Ia) data, we obtain the bounds on total neutrino masses Mν with the approximation of degenerate neutrino masses and for three dark energy models: the cosmological constant (ΛCDM) model, a phenomenological emergent dark energy (PEDE) model and a model-independent

    更新日期:2020-09-09
  • Ghost problems from Pauli–Villars to fourth-order quantum gravity and their resolution
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-09-05
    Philip D. Mannheim

    We review the history of the ghost problem in quantum field theory from the Pauli–Villars regulator theory to currently popular fourth-order derivative quantum gravity theories. While these theories all appear to have unitarity-violating ghost states with negative norm, we show that in fact these ghost states only appear because the theories are being formulated in the wrong Hilbert space. In these

    更新日期:2020-09-08
  • Screening away the H0 tension
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-09-05
    Jose Beltrán Jiménez; Dario Bettoni; Philippe Brax

    This Essay explores consequences of a dark nonlinear electromagnetic sector in a universe with a net dark charge for matter. The cosmological dynamics can be described by a Lemaître model and can be understood, thanks to a screening mechanism driven by the electromagnetic nonlinearities that suppress the dark force on small scales. Only at low redshift, when the screening scale enters the Hubble horizon

    更新日期:2020-09-08
  • Self-gravitating dark matter gets in shape
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-09-05
    Jenny Wagner

    In our current best cosmological model, the vast majority of matter in the universe is dark, consisting of yet undetected, nonbaryonic particles that do not interact electro-magnetically. So far, the only significant evidence for dark matter has been found in its gravitational interaction, as observed in galaxy rotation curves or gravitational lensing effects. The inferred dark matter agglomerations

    更新日期:2020-09-08
  • Geometry creates inertia
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-09-05
    Amitabha Lahiri

    The dynamics of fermions in curved spacetime is governed by a spin connection, a part of which is contorsion, an auxiliary field independent of the metric, without dynamics but fully expressible in terms of the axial current density of fermions. Its effect is the appearance of a quartic interaction involving all fermions. Contorsion can couple to left- and right-handed fermions with different strengths

    更新日期:2020-09-08
  • There is no coincidence after all!
    Int. J. Mod. Phys. D (IF 2.154) Pub Date : 2020-09-03
    Saurya Das

    We show that if Dark Matter is made up of light bosons, they form a Bose–Einstein condensate in the early Universe. This in turn naturally induces a Dark Energy of approximately equal density and exerting negative pressure. This explains the so-called coincidence problem.

    更新日期:2020-09-03
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