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Signatures of the accelerating black holes with a cosmological constant from the Sgr [formula omitted] and [formula omitted] shadow prospects Phys. Dark Universe (IF 5.5) Pub Date : 2024-04-18 L. Chakhchi, H. El Moumni, K. Masmar
Recently, the Event Horizon Telescope (EHT) achieved the realization of an image of the supermassive black hole showing an angular shadow diameter and the fractional deviation , alongside the earlier image of with angular diameter , deviation and deviations from circularity estimated to be . In addition, the shadow radii are assessed within the ranges for and as well as for using the Very Large Telescope
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Current and future cosmological impact of microwave background temperature measurements Phys. Dark Universe (IF 5.5) Pub Date : 2024-04-17 C.J.A.P. Martins, A.M.M. Vieira
The redshift dependence of the cosmic microwave background temperature, , is a key prediction of standard cosmology, but this relation is violated in many extensions thereof. Current astrophysical facilities can probe it in the redshift range . We extend recent work by Gelo et al. (2022) showing that for several classes of models (all of which aim to provide alternative mechanisms for the recent acceleration
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Dark matter signatures of black holes with Yukawa potential Phys. Dark Universe (IF 5.5) Pub Date : 2024-04-16 A.A. Araújo Filho, Kimet Jusufi, B. Cuadros-Melgar, Genly Leon
This study uses a nonsingular Yukawa-modified potential to obtain a static and spherically symmetric black hole solution with a cosmological constant. Such Yukawa-like corrections are encoded in two parameters, and , that modify Newton’s law of gravity in large distances, and a deformation parameter , which plays an essential role in short distances. The most significant effect is encoded in , which
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Probing dark matter via strong gravitational lensing by black holes Phys. Dark Universe (IF 5.5) Pub Date : 2024-04-16 Amnish Vachher, Dharmanand Baboolal, Sushant G. Ghosh
After obtaining an exact solution, we study gravitational lensing in strong-field limit by a static spherically symmetric charged black hole immersed in the perfect fluid dark matter (PFDM) having additional parameters and , respectively, because of PFDM and nonlinear electrodynamics. We observe a decrease in the deflection angle , photon sphere radius , and angular position with parameters and , meanwhile
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The cosmological constant problem and the extra dimensions of [formula omitted]=2 [formula omitted]=5 supergravity Phys. Dark Universe (IF 5.5) Pub Date : 2024-04-14 Safinaz Salem
We propose an interpretation for the cosmological constant problem based on modeling the universe as a 3-brane embedded in the bulk of 5-dimensional supergravity with hypermultiplets. When solving the modified Friedmann equations the complex structure moduli of the Calabi-Yau manifold cancel the large value of the vacuum energy density on the brane, wherein this value transfers to an Anti-de Sitter
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Friedmann equations of the fractal apparent horizon Phys. Dark Universe (IF 5.5) Pub Date : 2024-04-12 R. Jalalzadeh, S. Jalalzadeh, A. Sayahian Jahromi, H. Moradpour
From a fractal perspective, the entropy bound of gravitational systems undergoes changes. Furthermore, in the cosmological setting, the conservation law of a perfect fluid is also altered in such systems, affecting spatial elements like volume, area, and radius. By applying the first law of thermodynamics and deriving the Friedmann equations, we can gain insight into the evolution of such a fractal
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Testing gravitational lensing effects by supermassive massive black holes with superstring theory metric: Astrophysical implications and EHT constraints Phys. Dark Universe (IF 5.5) Pub Date : 2024-04-09 Niyaz Uddin Molla, Sushant G. Ghosh, Ujjal Debnath
We investigate gravitational lensing, both strong and weak, induced by charged black holes within heterotic superstring theory – -corrected Reissner–Nordström (RN) black holes characterized by an additional parameter, denoted as , in addition to mass and charge . Our findings reveal that as the parameter increases, various crucial parameters such as the unstable photon orbit radius , critical impact
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Compatibility of JWST results with exotic halos Phys. Dark Universe (IF 5.5) Pub Date : 2024-04-09 Fabio Iocco, Luca Visinelli
The James Webb Space Telescope (JWST) is unveiling astounding results about the first few hundred million years of life of the Universe, delivering images of galaxies at very high redshifts. Here, we develop a UV luminosity function model for high-redshift galaxies, considering parameters such as the stellar formation rate, dust extinction, and halo mass function. Calibration of this luminosity function
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Cosmic entropic acceleration from supermassive black hole growth Phys. Dark Universe (IF 5.5) Pub Date : 2024-04-08 Juan García-Bellido
General Relativistic Entropic Acceleration (GREA) gives a general framework in which to study multiple out-of-equilibrium phenomena in the context of general relativity, like the late accelerated expansion of the universe or the formation of galaxies and the large scale structure of the universe. Here we study the consequences of mass accretion onto massive Black Holes. We find that a population of
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Gravitoelectromagnetic quadrirefringence Phys. Dark Universe (IF 5.5) Pub Date : 2024-04-04 Antonio Enea Romano, Sergio A. Vallejo-Peña
We develop an effective approach for the study of the interaction of gravitational waves (GWs) and electromagnetic waves (EMWs), showing that quadrirefringence can be produced, a phenomenon consisting in a frequency and polarization dependency of the speed of the different polarizations of GWs and EMWs, which is also inducing a frequency and polarization dependent modification of the GW-EMW luminosity
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Shadow of novel rotating black hole in GR coupled to nonlinear electrodynamics and constraints from EHT results Phys. Dark Universe (IF 5.5) Pub Date : 2024-04-04 Muhammad Ali Raza, Javlon Rayimbaev, Furkat Sarikulov, M. Zubair, Bobomurat Ahmedov, Zdeněk Stuchlík
We study the optical properties of spacetime around a novel black hole in general relativity coupled to nonlinear electrodynamics, which is asymptotically flat. First, we study the angular velocity and Lyapunov exponent in unstable photon circular orbits in the novel spherically symmetric black hole spacetime. Later, we obtain the rotating black hole solution using the Newman–Janis algorithm and determine
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Slow-rolling scalar dynamics as solution for the Hubble tension Phys. Dark Universe (IF 5.5) Pub Date : 2024-04-03 Giovanni Montani, Nakia Carlevaro, Maria Giovanna Dainotti
We construct a theoretical framework to interpret the Hubble tension by means of a slow-rolling dynamics of a self-interacting scalar field. In particular, we split the Friedmann equation in order to construct a system for the three unknowns, corresponding to the Hubble parameter , the scalar field and its self-interaction potential , as functions of the redshift. In the resulting picture, the vacuum
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Dark torsion oscillations and bounces induced by Barbero-Immirzi and quantum correction on Einstein-Cartan gravity with very light inflatons Phys. Dark Universe (IF 5.5) Pub Date : 2024-04-03 L.C. Garcia de Andrade
In this paper we present several examples of how to constrain loop quantum gravity Barbero-Immirzi (BI) parameter, either by using quantum corrections in Nieh–Yan (NY) modified Einstein-Cartan (EC) gravity with the Holst term. The reason why we introduce some extra terms in the actions, is that even when one adds both NY and Holst terms, being topological terms, they do not contribute to the dynamics
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Speed of sound and scalar spectral index: Reconstructing inflation and reheating in a non-canonical theory Phys. Dark Universe (IF 5.5) Pub Date : 2024-04-02 Ramón Herrera, Carlos Ríos
In this article we analyze the reconstruction of inflation in the framework of a non-canonical theory. In this sense, we study the viability of reconstructing the background variables assuming a non-linear kinetic term given by , with the standard kinetic term associated to the scalar field and an arbitrary coupling function. In order to achieve this reconstruction in the context of inflation, we assume
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Stability of a realistic astrophysical pulsar and its mass–radius relation in higher-order curvature gravity Phys. Dark Universe (IF 5.5) Pub Date : 2024-04-02 G.G.L. Nashed, Kazuharu Bamba
The objective of this research is to explore compact celestial objects while considering the framework of an extended gravitational theory known as gravity. The notations and denote the Ricci scalar and the Gauss–Bonnet invariant, respectively. Radio pulsars, which are neutron stars with masses greater than 1.8 times that of the Sun (), provide exceptional opportunities for delving into fundamental
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Charged particle dynamics in Reissner–Nordström–Tangherlini spacetime Phys. Dark Universe (IF 5.5) Pub Date : 2024-04-02 Ozodbek Rahimov, Bobir Toshmatov, Yuriy Vyblyi, Abdimirkhakim Akhmedov, Bahromjon Abdulazizov
In this paper we investigate the motion of electrically charged test particle orbiting electrically charged higher dimensional Reissner–Nordström black holes. Specifically, we analyze the radii of the photonsphere and shadow, the innermost stable circular orbits, and the capture cross section of charged particles across various dimensions of spacetime. Our study in the capture of the charged particle
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Structure formation in various dynamical dark energy scenarios Phys. Dark Universe (IF 5.5) Pub Date : 2024-04-01 Masoume Reyhani, Mahdi Najafi, Javad T. Firouzjaee, Eleonora Di Valentino
This research investigates the impact of the nature of Dark Energy (DE) on structure formation, focusing on the matter power spectrum and the Integrated Sachs–Wolfe effect (ISW). By analyzing the matter power spectrum at redshifts and , as well as the ISW effect on the scale of , the study provides valuable insights into the influence of DE equations of state (EoS) on structure formation. The findings
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The evolution and diagnosis in late-time [formula omitted] dark energy model Phys. Dark Universe (IF 5.5) Pub Date : 2024-04-01 Yitao Wang, Weiqiang Yang, Yannan Qi, Tianyi Han, Yabo Wu
We systematically review some standard problems and recent developments in modified gravitation in cosmology, and in this paper study the late-time dynamics of the gravity model. We discuss three important issues, namely the cosmological evolution of the gravity model, statefinder geometric diagnosis, and cosmological implications from supernova observations. We will solve the field equation appropriately
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Tidal forces in the Simpson–Visser black-bounce and wormhole spacetimes Phys. Dark Universe (IF 5.5) Pub Date : 2024-04-01 Dhruv Arora, Parth Bambhaniya, Dipanjan Dey, Pankaj S. Joshi
The concept of regular black holes has gained attention in recent years, especially in the context of quantum gravity theories. In these theories, the existence of singularities is paradoxical as they represent a breakdown of the laws of physics. Motivated by the recent developments in this area, we study the tidal force effects in one such family of regular geometries described by the Simpson–Visser
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Noncommutative Schwarzschild black hole surrounded by quintessence: Thermodynamics, Shadows and Quasinormal modes Phys. Dark Universe (IF 5.5) Pub Date : 2024-04-01 B. Hamil, B.C. Lütfüoğlu
In Campos et al. (2022), Campos et al studied the quasinormal modes and shadows of noncommutative Schwarzschild black holes. Since we know that the quintessence matter surrounding black holes has significant effects on the black hole quantities, in this study, we aimed to show this influence by revisiting the same problem in the presence of quintessence matter field. To this end, we first examined
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Inflation and reheating predictions in [formula omitted]-gravity Phys. Dark Universe (IF 5.5) Pub Date : 2024-03-30 Feng-Yi Zhang, Hongwei Yu, Wenbin Lin
We study the slow-roll inflation driven by a scalar field with a power-law potential and the reheating within the framework of -gravity. We find that -gravity will suppress the tensor-to-scalar ratio, and thus some inflation models, which are inconsistent with the latest cosmic microwave background radiation (CMB) data in the framework of general relativity, may become compatible with the CMB observations
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Constraining light scalar field with torsion-balance gravity experiments Phys. Dark Universe (IF 5.5) Pub Date : 2024-03-30 Cheng-Gang Qin, Xiao-Yu Lu, Bing-Chen Zhao, Jun Ke, An-Bin Du, Jie Luo, Yu-Jie Tan, Cheng-Gang Shao
The light scalar field with a coupling to standard model particles provide a possible source of the long-range Yukawa forces or violation of the weak equivalence principle, which can be potentially explored by precision gravity experiments. We describe the searches for such light scalar fields with the three types of gravity experiments, including the -measurement experiments, Inverse-Square Law (ISL)
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Graviton-photon oscillations in an expanding universe Phys. Dark Universe (IF 5.5) Pub Date : 2024-03-27 Peter Anninos, Tony Rothman, Andrea Palessandro
Through the Gertsenshtein effect, the presence of a large external B-field may allow photons and gravitons to mix in a way that resembles neutrino oscillations and is even more similar to axion-photon mixing. Assuming a background B-field (or any field that behaves like one), we examine the Gertsenshtein mechanism in the context of FLRW expanding universe models, as well as de Sitter space. The conformal
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Thin-shell gravastar in a noncommutative BTZ geometry Phys. Dark Universe (IF 5.5) Pub Date : 2024-03-27 A.T.N. Silva, M.A. Anacleto, L. Casarini
In this paper, we build a thin-shell gravastar model within a noncommutative BTZ geometry. For this, we consider a noncommutative BTZ metric in the inner region and a geometry associated with a BTZ solution in the outer region, joined by the generalized join technique. After investigating the inner spacetime, surface and outer spacetime, we observe that there is a surface energy density and surface
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Induced cosmological anisotropy by a gauge-gravity interaction Phys. Dark Universe (IF 5.5) Pub Date : 2024-03-25 Bum-Hoon Lee, Hocheol Lee, Wonwoo Lee, Nils A. Nilsson, Somyadip Thakur
We present a simple model which generates cosmological anisotropies on top of standard FLRW geometry. This is in some sense reminiscent of the mean field approximation, where the mean field cosmological model under consideration would be the standard FLRW, and the anisotropy is a small perturbative correction on top of it. Using a supergravity-inspired model, we confirm that the stable fixed point
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Black holes thermodynamics with CFT re-scaling Phys. Dark Universe (IF 5.5) Pub Date : 2024-03-23 Yahya Ladghami, Taoufik Ouali
In this paper, we study the thermodynamic behavior of charged AdS black holes in a conformal holographic extended thermodynamic. Our setup is constructed using a new dictionary that relates AdS black hole quantities to the corresponding dual conformal fields theory (CFT) one, with the conformal factor being treated as a variable thermodynamic. In this thermodynamic study, we investigate the critical
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Barrow entropy and AdS black holes in RPS thermodynamics Phys. Dark Universe (IF 5.5) Pub Date : 2024-03-23 Yahya Ladghami, Brahim Asfour, Amine Bouali, Ahmed Errahmani, Taoufik Ouali
In this paper, we examine the restricted phase space (RPS) thermodynamics for charged AdS black holes by considering the impact of quantum gravity on the event horizon area. The primary aim of this work is to elucidate the influence of quantum gravitational effects on thermodynamic behaviors, critical phenomena, phase transitions, and the stability of black holes. We observe that charged AdS black
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Wave-optics limit of the stochastic gravitational wave background Phys. Dark Universe (IF 5.5) Pub Date : 2024-03-22 Alice Garoffolo
The stochastic gravitational wave background (SGWB) is a rich resource of cosmological information, encoded both in its source statistics and anisotropies induced by propagation effects. We provide a theoretical description of it, without employing tools which rely on the geometric optics assumption. Our formalism is based on the so-called and it is able to capture wave-optics effects, such as interference
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Spontaneous baryogenesis and generation of gravitational waves in a new model of quintessential [formula omitted]-attractor Phys. Dark Universe (IF 5.5) Pub Date : 2024-03-21 Arunoday Sarkar, Buddhadeb Ghosh
We study the role of -parameter of the newly proposed model of quintessential -attractor inflation (arXiv: 2305.00230 [gr-qc]) to the case of quintessential spontaneous baryogenesis and generation of relic gravitational waves in presence of a rolling scalar field during kination. An technique has been employed to compute the freeze-out temperature and the baryon-to-entropy ratio, of which the obtained
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Observational signatures of Rotating compact objects in Plasma space–time Phys. Dark Universe (IF 5.5) Pub Date : 2024-03-21 Saurabh Kumar, Akhil Uniyal, Sayan Chakrabarti
We have investigated the characteristics of shadows cast by the Kerr black hole in the presence of plasma and compared them to those of a rotating wormhole in a uniform plasma space–time for an observer at infinity. Interestingly, for the same uniform plasma density, the apparent shadow size of the rotating wormhole is always greater than that of the Kerr black hole. To further distinguish the two
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Lensing convergence and anisotropic dark energy in galaxy redshift surveys Phys. Dark Universe (IF 5.5) Pub Date : 2024-03-20 Wilmar Cardona, Rubén Arjona, Savvas Nesseris
Analyses of upcoming galaxy surveys will require careful modelling of relevant observables such as the power spectrum of galaxy counts in harmonic space . We investigate the impact of disregarding relevant relativistic effects by considering a model of dark energy including constant sound speed , constant equation of state , and anisotropic stress sourced by matter perturbations . Cosmological constraints
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Holographic image features of Hayward-AdS black hole surrounded by quintessence dark energy Phys. Dark Universe (IF 5.5) Pub Date : 2024-03-20 Ke-Jian He, Yi-Wen Han, Guo-Ping Li
By employing the AdS/CFT correspondence, we investigate the holographic images of Hayward-AdS black hole enveloped by quintessence dark energy. The AdS boundary is equipped with a Gaussian oscillation source, which give rise to the response generated on the opposing side of the boundary after it propagated in the bulk. With the aid of a special wave optics system, the holographic images of black hole
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Effect of scalar hair on magnetically charge Euler-Heisenberg AdS black hole via extended phase transition Phys. Dark Universe (IF 5.5) Pub Date : 2024-03-19 R.H. Ali, G. Abbas, G. Mustafa
In this article, we have studied numerous thermodynamical aspects and the extended phase space of the AdS magnetically charged Euler-Heisenberg BH minimally coupled to a scalar field. We investigated the ADM mass, Hawking temperature, entropy, specific heat, Gibss free energy (both locally and globally) and P-V criticality at the horizon radius. Our result shows that the maximum value for the Hawking
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Extension of Hayward black hole in [formula omitted] gravity coupled with a scalar field Phys. Dark Universe (IF 5.5) Pub Date : 2024-03-18 G.G.L. Nashed
This study looks into regular black hole solutions in a theory of gravity called gravity, which also involves a scalar field. The theory changes Einstein’s ideas by adding a new function related to something called the Ricci scalar. This lets us tweak the equations that describe how gravity works. Adding a scalar field makes the theory more interesting, giving us more ways to investigate and understand
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f(R) gravity in an ellipsoidal universe Phys. Dark Universe (IF 5.5) Pub Date : 2024-03-16 Cemsinan Deliduman, Oğuzhan Kaşıkçı, Vildan Keleş Tuğyanoğlu
We propose a new model of cosmology based on an anisotropic background and a specific theory of gravity. It is shown that field equations of gravity in a Bianchi type I background give rise to a modified Friedmann equation. This model contains two important parameters: and . We, thus, simply call our model CDM. It is distinguished in two important aspects from the CDM model: firstly, the contribution
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Observational appearance of the spherically symmetric black hole in PFDM Phys. Dark Universe (IF 5.5) Pub Date : 2024-03-16 Xuetao Yang
We investigate the observational appearance of spherically symmetric black holes in perfect fluid dark matter (PFDM), with the celestial sphere and an accretion disk being light sources. For the celestial sphere model, we show the variations in black holes’ appearance from different angles. And for an optically thin accretion disk, the intensity observed can be characterized by the redshift factor
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Attractor behavior of [formula omitted] modified gravity and the cosmic acceleration Phys. Dark Universe (IF 5.5) Pub Date : 2024-03-16 L.K. Duchaniya, Kanika Gandhi, B. Mishra
In this paper, we have performed the dynamical system analysis of gravity cosmological models at both background and perturbation levels. We have presented three models pertaining to three distinct functional forms of . The first form is that of the logarithmic form of the torsion scalar , the second one is in the power law form, and the third one is the combination of the first two forms. For all
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Classical and quantum solutions in scalar field cosmology via the Eisenhart lift and linearization Phys. Dark Universe (IF 5.5) Pub Date : 2024-03-15 Andronikos Paliathanasis
This study introduces a novel approach for solving the cosmological field equations within scalar field theory by employing the Eisenhart lift. The field equations are reformulated as a system of geodesic equations for the Eisenhart metric. In the case of an exponential potential, the Eisenhart metric is shown to be conformally flat. By applying basic geometric principles, a new set of dynamical variables
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Putting flat [formula omitted]CDM in the (Redshift) bin Phys. Dark Universe (IF 5.5) Pub Date : 2024-03-15 E. Ó Colgáin, M.M. Sheikh-Jabbari, R. Solomon, M.G. Dainotti, D. Stojkovic
Flat CDM cosmology is specified by two constant fitting parameters at the background level in the late Universe, the Hubble constant and matter density (today) . Mathematically, and are either integration constants arising from solving ordinary differential equations or are directly related to integration constants. Seen in this context, if fits of the CDM model to cosmological probes at different
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Gravitationally induced matter creation in scalar–tensor [formula omitted] gravity Phys. Dark Universe (IF 5.5) Pub Date : 2024-03-12 Ricardo A.C. Cipriano, Tiberiu Harko, Francisco S.N. Lobo, Miguel A.S. Pinto, João Luís Rosa
In this work, we analyze the possibility of gravitationally induced matter creation in the so-called Energy–Momentum-Squared gravity (EMSG), i.e. gravity, in its dynamically equivalent scalar–tensor representation. Given the explicit nonminimal coupling between matter and geometry in this theory, the energy–momentum tensor is not generally covariantly conserved, which motivates the study of cosmological
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Particle production from non-minimal coupling in a symmetry breaking potential transporting vacuum energy Phys. Dark Universe (IF 5.5) Pub Date : 2024-03-12 Alessio Belfiglio, Youri Carloni, Orlando Luongo
We propose an inflationary scenario where the inflaton field is non-minimally coupled to spacetime curvature and inflation is driven by a vacuum energy symmetry breaking potential without specifying whether the inflaton field is small or large. As we incorporate vacuum energy into our analysis, we further explore the implications of a non-zero potential offset within inflationary dynamics. We propose
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Corrigendum to “Relic abundance of dark matter with coannihilation in non-standard cosmological scenarios” [Physics of the Dark Universe 44 (2024) 101441] Phys. Dark Universe (IF 5.5) Pub Date : 2024-03-07 Fangyu Liu, Hoernisa Iminniyaz
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No Cauchy horizon in a gravitational decoupled Reissner–Nordström spacetime Phys. Dark Universe (IF 5.5) Pub Date : 2024-03-06 Francisco Tello-Ortiz, Muhammad Ali Raza, M. Zubair, Y. Gómez-Leyton
In this article, using gravitational decoupling by means of the extended geometric deformation approach, we obtain a new hairy spherically symmetric and asymptotically flat charged black hole solution starting from the well known Reissner–Nordström manifold. The resulting spacetime, is characterized by a spacelike singularity at , which is protected by an event horizon , where the original Cauchy horizon
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Exploring non-perturbative corrections in thermodynamics of static dirty black holes Phys. Dark Universe (IF 5.5) Pub Date : 2024-03-06 Saheb Soroushfar, Behnam Pourhassan, İzzet Sakallı
This research delves into an extensive exploration of the thermodynamic characteristics exhibited by a contaminated black hole subject to a uniform electric field, within the theoretical framework of the Einstein-Nonlinear Electrodynamics (ENE)-dilaton theory. The investigation encompasses a thorough analysis of diverse thermodynamic facets, encompassing heat capacity, Helmholtz free energy, and internal
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Dynamical system analysis in multiscalar-torsion cosmology Phys. Dark Universe (IF 5.5) Pub Date : 2024-03-05 Genly Leon, Andronikos Paliathanasis, Alfredo D. Millano
We explore the phase-space of a multiscalar-torsion gravitational theory within a cosmological framework characterized by a spatially flat Friedmann–Lemaître–Robertson–Walker model. Our investigation focuses on teleparallelism and involves a gravitational model featuring two scalar fields, where one scalar field is coupled to the torsion scalar. We consider coupling in the two scalar fields’ kinetic
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Thermodynamic topology of 4D Euler–Heisenberg-AdS black hole in different ensembles Phys. Dark Universe (IF 5.5) Pub Date : 2024-02-28 Naba Jyoti Gogoi, Prabwal Phukon
We study the thermodynamic topology of 4D Euler-Heisenberg-AdS (EHAdS) black hole and higher-order QED corrected Euler-Heisenberg-AdS black hole in different ensembles using generalized off-shell free energy. In this approach, black holes are viewed as defects in the thermodynamic space. We work in two ensembles: canonical ensemble in which the charge is kept fixed and grand canonical ensemble in which
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Rotating black holes surrounded by a dark matter halo in the galactic center of M87 and Sgr A∗ Phys. Dark Universe (IF 5.5) Pub Date : 2024-02-28 S.R. Wu, B.Q. Wang, Z.W. Long, Hao Chen
In this paper, we construct the solutions of modified Schwarzschild spacetime with three kinds of dark matter profiles, i.e. the Beta profiles, Moore profiles and Fermionic halos profiles. In order to make the models more realistic, by using the modified Newman–Janis algorithm (MNJA), we extend our solution to obtain three rotating black holes surrounded by dark matter halo and discuss the black hole
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Astrophysical implications of quantum-improved charged black holes: Insights into quantum gravity and black hole phenomena Phys. Dark Universe (IF 5.5) Pub Date : 2024-02-21 Faisal Javed
This study examines the quantum-improved charged black hole and examines the influence of higher-order thermal fluctuations on its corrected energies. The research aims to assess the null geodesics, shadow radius, quasinormal modes, and emission energy of the black hole. Observations are made on the impact of the quantum parameter and charge of the black hole geometry on the Schwarzschild black hole
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Emulating dark energy models with known equation of state via the created cold dark matter scenario Phys. Dark Universe (IF 5.5) Pub Date : 2024-02-20 Víctor H. Cárdenas, Miguel Cruz
In this work we establish only at background dynamics level, the equivalence between the Created Cold Dark Matter (CCDM) model and diverse dark energy (DE) models. We find that for a barotropic or linear equation of state (EoS) for the DE, , and standard matter sector the corresponding CCDM model is described by the same functional structure of the ratio of particle production, . For a different EoS
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Beyond ΛCDM with f(z)CDM: Criticalities and solutions of Padé Cosmography Phys. Dark Universe (IF 5.5) Pub Date : 2024-02-20 A. Turmina Petreca, M. Benetti, S. Capozziello
Recently, cosmography emerged as a valuable tool to effectively describe the vast amount of astrophysical observations without relying on a specific cosmological model. Its model-independent nature ensures a faithful representation of data, free from theoretical biases. Indeed, the commonly assumed fiducial model, the CDM, shows some shortcomings and tensions between data at late and early times that
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Emergence of cosmic space and the maximization of horizon entropy Phys. Dark Universe (IF 5.5) Pub Date : 2024-02-20 P.B. Krishna, Titus K. Mathew
The spatial expansion of the universe can be described as the emergence of space with the progress of cosmic time, through a simple equation, . This law of emergence suggested by Padmanabhan in the context of general relativity for a flat universe has been generalized by Sheykhi to Gauss Bonnet and Lovelock gravity for a universe with any spatial curvature. We investigate whether this generalized holographic
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The excess of diffuse radio emission in galaxy clusters A4038 and A1664 Phys. Dark Universe (IF 5.5) Pub Date : 2024-02-20 Z.Z. Abidin, N. Asmi, M.R. Mat Sabri, M.A. Rohaizi, N. Hashim, U.F.S.U. Ibrahim
In this study, we investigate the potential connection between Dark matter (DM) particles and synchrotron emission in galaxy clusters, with a focus on radio relics. We explore three models beyond the standard model of particle physics and calculate emissions from DM particle candidates, comparing the results to radio observations. Our analysis centres on galaxy clusters A4038 and A1664, considering
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Nonextensive entropies impact onto thermodynamics and phase structure of Kerr–Newman black holes Phys. Dark Universe (IF 5.5) Pub Date : 2024-02-17 S. Ghaffari, G.G. Luciano, A. Sheykhi
Taking the nonextensive Tsallis and Rényi entropies into account, we explore thermodynamic properties and phase transitions of the Kerr–Newman black holes (KNBH) in the microcanonical and canonical ensembles. We also compare our results with those obtained by attributing the Bekenstein–Hawking entropy bound to the mentioned black holes. Our analysis indicates that, similarly to the standard Boltzmann
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Generating exact polytropes in non-conservative unimodular geometries Phys. Dark Universe (IF 5.5) Pub Date : 2024-02-16 Sudan Hansraj, Chevarra Hansraj, Njabulo Mkhize, Abdelghani Errehymy, Christian G. Böhmer
The trace-free Einstein equations contain one equation less than the complete field equations. In a static and spherically symmetric spacetime, the number of field equations is thus reduced to two. The equation of pressure isotropy of general relativity, however, is preserved thus showing that any known perfect fluid spacetime is a suitable candidate for the trace-free scenario. The extra freedom in
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Traversable wormholes with weak gravitational lensing effect in f(R,T) gravity Phys. Dark Universe (IF 5.5) Pub Date : 2024-02-16 Nayan Sarkar, Susmita Sarkar, Abdelmalek Bouzenada, Abhisek Dutta, Moumita Sarkar, Farook Rahaman
In this article, we have introduced completely new asymptotically flat Morris-Thorne traversable wormhole geometries supported by anisotropic matter in the framework of gravity whereas the isotropic matter content does not support the wormhole structure. The reported shape functions are nicely fitted in the construction of wormhole geometries by satisfying all the essential conditions. The wormhole
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Muon g−2, dark matter, and neutrino mass explanations in a modular A4 symmetry Phys. Dark Universe (IF 5.5) Pub Date : 2024-02-15 Parada T.P. Hutauruk, Dong Woo Kang, Jongkuk Kim, Hiroshi Okada
We study a successful model to explain the muon anomalous magnetic moment originating from Yukawa-type interactions in a supersymmetric theory. Thanks to a modular flavor symmetry, any lepton flavor violations that spoil the model are forbidden. We also investigate a predictive radiative seesaw model including a dark matter (DM) candidate. At first, we construct the minimum model to satisfy the neutrino
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Shadows of R-charged black holes in AdS5 Phys. Dark Universe (IF 5.5) Pub Date : 2024-02-15 Yassine Sekhmani, Dhruba Jyoti Gogoi, M. Koussour, Ratbay Myrzakulov, Javlon Rayimbaev
Motivated by Anti-de Sitter (AdS) black hole solutions of five-dimensional gauged extended supergravities, the shadow behavior of R-charged black holes is examined. This process gets analyzed in terms of four charge configurations, namely, three unequal charges, three equal charges, two equal charges, and one single charge. Results on shadow behavior show the influence of electric charge on the geometry
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Non-perturbative correction on the black hole geometry Phys. Dark Universe (IF 5.5) Pub Date : 2024-02-13 Behnam Pourhassan, Hoda Farahani, Farideh Kazemian, İzzet Sakallı, Sudhaker Upadhyay, Dharm Veer Singh
In this paper, we use the holographic principle to obtain a modified metric of black holes that reproduces the exponentially corrected entropy. The exponential correction of the black hole entropy comes from non-perturbative corrections. It interprets as a quantum effect which affects black hole thermodynamics especially in the infinitesimal scales. Hence, it may affect black hole stability at the
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Relic abundance of dark matter with coannihilation in non-standard cosmological scenarios Phys. Dark Universe (IF 5.5) Pub Date : 2024-02-13 Fangyu Liu, Hoernisa Iminniyaz
We investigate the relic abundance of dark matter from coannihilation in non-standard cosmological scenarios. We explore the effect of coannihilation on the relic density of dark matter and freeze out temperature in quintessence model with kination phase and brane world cosmological scenarios. Since the Hubble expansion rate is enhanced in quintessence and brane world cosmological models, it causes
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The first variation of the matter energy–momentum tensor with respect to the metric, and its implications on modified gravity theories Phys. Dark Universe (IF 5.5) Pub Date : 2024-02-13 Zahra Haghani, Tiberiu Harko, Shahab Shahidi
The first order variation of the matter energy–momentum tensor with respect to the metric tensor plays an important role in modified gravity theories with geometry-matter coupling, and in particular in the modified gravity theory. We obtain the expression of the variation for the baryonic matter described by an equation given in a parametric form, with the basic thermodynamic variables represented