Article
Astronomy & Astrophysics
Abolhassan Mohammadi
Summary: This study investigates the scenario of constant-roll inflation caused by holographic dark energy with an energy density of 3Mp2c2/L2. The observable parameters at the time of inflation are obtained and the constants of the model are determined by comparing with data. The estimated energy scale of inflation is about 1016 GeV.
PHYSICS OF THE DARK UNIVERSE
(2022)
Article
Physics, Particles & Fields
P. Suresh Kumar, Bramha Dutta Pandey, Umesh Kumar Sharma, C. Pankaj
Summary: By extending the holographic principle to a cosmological framework and combining it with the Kaniadakis entropy, the non-flat Kaniadakis holographic dark energy model is constructed. The model describes the evolutionary behavior of the universe and can explain both open and closed universe models. It also provides insights into the thermal history of the universe and the quintom scenario.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Optics
Syed Yasir Azeem, Dong Zhao, Ruixing Xia, Kun Huang
Summary: This study demonstrates that carefully designed complementary metasurfaces can generate two different holographic images in the visible light range, challenging the predictions of Babinet's principle.
CHINESE OPTICS LETTERS
(2023)
Article
Physics, Particles & Fields
Yu-Qi Dong, Yu-Qiang Liu, Yu-Xiao Liu
Summary: In this study, we explore the parameter space and gravitational waves in a spatially flat Universe in the context of Palatini-Horndeski theory. We develop a general method to determine the speed of gravitational waves in the Palatini formalism in a cosmological background and find that if the theory satisfies the condition that the tensor gravitational wave speed is equal to the speed of light c in any spatially flat cosmological background, then only the action S=integral d4x-g[K(phi ,X)-G3(phi ,X)square~phi +G4(phi )R~] remains as a possible action in Palatini-Horndeski theory. Additionally, we find that when G5(phi ,X) is not equal to 0, the tensor component of the connection propagates and there are two different tensor gravitational wave speeds.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Astronomy & Astrophysics
Abolhassan Mohammadi, Tayeb Golanbari, Kazuharu Bamba, Iarley P. Lobo
Summary: The application of holographic principle in early and late-time evolution, especially during inflation, shows that modifying entropy can result in changes in energy density. Through the use of Tsallis entropy and GO length scale, parameters of the model are calculated, establishing a correspondence between holographic dark energy and scalar field, and considering the trans-Planckian censorship conjecture.
Article
Physics, Particles & Fields
Niki Drepanou, Andreas Lymperis, Emmanuel N. Saridakis, Kuralay Yesmakhanova
Summary: We propose a holographic dark energy scenario based on Kaniadakis entropy, using the future event horizon as the cutoff. We derive the differential equation for the evolution of the effective dark energy density parameter and provide analytical expressions for the equation-of-state and deceleration parameters. Our results show that the universe undergoes a standard thermal history, with the transition to acceleration occurring at z approximately 0.6. The dark energy equation-of-state parameter exhibits a rich behavior, being quintessence-like, phantom-like, or experiencing the phantom-divide crossing in the past or future. In the far future, dark energy dominates completely, with the asymptotic value of its equation of state depending on the model parameters.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Physics, Particles & Fields
Gabriela Barenboim, Christopher T. Hill
Summary: The study presents an effective field theory (EFT) model for describing matter field interactions with Schwarzschild mini-black-holes (SBH's) and considers fermion interactions with SBH's. It suggests that the information field can be promoted to a dynamical field, leading to a tachyonic instability and breaking the vacuum to SU(N)xU(1)/SO(N). The model implies the existence of many scalar fields bound nonperturbatively by gravity.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Physics, Particles & Fields
M. Dheepika, Titus K. Mathew
Summary: In this study, we considered the interacting Tsallis Holographic Dark Energy model. We analytically solved for the Hubble parameter and used observational data to constrain the model parameters. The results showed that without interaction, the model behaves like ΛCDM, but with interaction, the model exhibits quintessence behavior and eventually enters the de Sitter phase.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Physics, Multidisciplinary
Kouki Kushihara, Keisuke Izumi, Tetsuya Shiromizu
Summary: The study on de Sitter entropy in the braneworld model with Gauss-Bonnet/Lovelock terms reveals that the de Sitter entropy computed through the Euclidean action coincides exactly with the holographic entanglement entropy.
PROGRESS OF THEORETICAL AND EXPERIMENTAL PHYSICS
(2021)
Review
Physics, Multidisciplinary
Shuang Wang, Miao Li
Summary: We review the theoretical aspects of holographic dark energy (HDE) in this paper, including the OHDE model and four types of HDE models originating from the holographic principle. From both theoretical and observational perspectives, HDE differs significantly from other dark energy theories and has the potential to fit astronomical data well and alleviate the Hubble tension problem.
COMMUNICATIONS IN THEORETICAL PHYSICS
(2023)
Article
Mechanics
P. Van
Summary: This paper analyzes the thermodynamic requirements using the Liu procedure, comparing it with the traditional method of divergence separation and emphasizing the role of spacetime. It shows that perfect Korteweg fluids are holographic and explores the conditions for a complex field to represent the density and velocity fields of the fluid, as well as the complex scalar field becoming a wave function of quantum mechanics. The bridge between field and particle representations is holography, with the Second Law of Thermodynamics being the key to holography.
Article
Physics, Multidisciplinary
A. N. Makarenko, A. V. Timoshkin
Summary: The holographic principle is applied to describe the early stage of the Universe's evolution, using viscous liquid and holographic cutoff concepts. Calculations of the infrared radius and derivation of energy conservation laws are conducted within this framework, presenting the viscous liquid as a generalization of holographic energy.
RUSSIAN PHYSICS JOURNAL
(2021)
Article
Astronomy & Astrophysics
Daniel Jimenez-Aguilar
Summary: In this study, a model of inflation and dark energy is proposed, in which the inflaton potential is constructed by assuming that a scalar field representing the classical energy of the spacetime foam inside the Hubble horizon is an exact solution to the cosmological equations. The resulting potential has the right properties to describe both the early and late expansion epochs of the universe in a unified picture.
PHYSICS OF THE DARK UNIVERSE
(2023)
Article
Physics, Particles & Fields
Spiros Cotsakis, Jose P. Mimoso, John Miritzis
Summary: In this paper, we discuss the implications of the cosmological frame principle which requires stable solutions of modified gravity to hold in two conformally-related frames. We demonstrate the existence of globally stable, 'frame-independent' solutions describing cosmic acceleration, suggesting their physical relevance. This result emphasizes the importance of further investigating the implications of the frame principle for cosmological properties relying on conformal frames.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Astronomy & Astrophysics
Sergei D. Odintsov, Simone D'Onofrio, Tanmoy Paul
Summary: The increasing interest in different entropy functions in cosmology raises the question of whether there is a generalized entropy that can unify all known entropies. A four-parameter generalized entropy has recently been formulated, which reduces to different known entropies in specific parameter limits. In this paper, the authors investigate the early phase of the universe's evolution, particularly from inflation to reheating, using the concept of entropic energy density. The results show that entropic energy can drive an early inflationary phase and the theoretical expectations are consistent with recent observational data.
PHYSICS OF THE DARK UNIVERSE
(2023)
Article
Physics, Particles & Fields
Emmanuel N. Saridakis, Weiqiang Yang, Supriya Pan, Fotios K. Anagnostopoulos, Spyros Basilakos
Summary: Soft cosmology extends the standard cosmology by allowing for different equation-of-state parameters for dark matter and dark energy at different scales. Data analysis suggests that soft cosmology is favored by observational constraints.
Article
Astronomy & Astrophysics
Dongdong Zhang, Jia-Rui Li, Jiaqi Yang, Yufei Zhang, Yi-Fu Cai, Wenjuan Fang, Chang Feng
Summary: We use the Ali Cosmic Microwave Background Polarization Telescope (AliCPT) to forecast the constraints on neutrino physics parameters using the Cosmic Microwave Background (CMB) temperature, E-mode polarization, and lensing spectra. Our numerical simulations show that AliCPT can achieve a precision of sigma(N (eff)) = 0.56 and M (nu) < 1.10 eV (95% CL.) for the first year of observation, based on TT, TE, EE, and CMB lensing power spectra. We also investigate how instrumental parameters such as noise level, FWHM, and sky coverage affect these constraints on neutrino parameters.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Shreya Banerjee, Sayantani Bera, David F. Mota
Summary: The Lambda-Cold Dark Matter model is currently the most accurate model for explaining cosmological observations, but there are still issues at galactic scales. Various models of dark matter, such as superfluid dark matter, Bose-Einstein Condensate (BEC) dark matter, and fuzzy dark matter, have been proposed to address these shortcomings. This study investigates these models using the constraint on gravitational wave propagation speed from the detection of the binary neutron star GW170817 by the LIGO-Virgo detector network. The findings suggest that the fuzzy dark matter model is the most feasible scenario to be tested in the near future, especially with detection frequencies < 10-9 Hz.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Theodoros Papanikolaou, Andreas Lymperis, Smaragda Lola, Emmanuel N. Saridakis
Summary: Primordial black holes (PBHs) can be formed through non-canonical inflation, and can provide observational evidence of the early Universe. Constraints on the non-canonical exponents are extracted by requiring significant PBH production. Asteroid-mass PBHs can explain the dark matter, and solar-mass PBHs within the LIGO-VIRGO detection band can be produced. The collapse of enhanced cosmological perturbations that form PBHs can also generate a detectable stochastic gravitational wave (GW) background.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Physics, Multidisciplinary
G. G. L. Nashed, Emmanuel N. Saridakis
Summary: In this study, new classes of anisotropic solutions are extracted within the framework of mimetic gravity. By applying the Tolman-Finch-Skea metric and a specific anisotropy unrelated to it, and smoothly matching the interior solution to the exterior Schwarzschild solution, the authors investigate various properties of these solutions. The results show positive energy density, decreasing pressures towards the center of the star, repulsive anisotropic force, and monotonically increasing equation-of-state parameters. The stability of the solutions is also examined, and it is found that the stars in all cases are stable.
EUROPEAN PHYSICAL JOURNAL PLUS
(2023)
Article
Chemistry, Multidisciplinary
Shreya Banerjee, Sunil K. Gupta, Erode N. Prabhakaran
Summary: The presence of sinusoidal synchronicity between rotational motion along C-alpha-C ' sigma bond and the concomitant pyramidalization of C ' in amides is demonstrated for the first time in solution. It has been found that synchronicity is perturbed when tau-rotation is 'locked' with interactions, resulting in a strain on the amide bond and a decrease in energy barrier for the amide bond cis/trans isomerism by approximately 1.68 kcal/mol.
Article
Physics, Multidisciplinary
Tinggui Wang, Guilin Liu, Zhenyi Cai, Jinjun Geng, Min Fang, Haoning He, Ji-an Jiang, Ning Jiang, Xu Kong, Bin Li, Ye Li, Wentao Luo, Zhizheng Pan, Xuefeng Wu, Ji Yang, Jiming Yu, Xianzhong Zheng, Qingfeng Zhu, Yi-Fu Cai, Yuanyuan Chen, Zhiwei Chen, Zigao Dai, Lulu Fan, Yizhong Fan, Wenjuan Fang, Zhicheng He, Lei Hu, Maokai Hu, Zhiping Jin, Zhibo Jiang, Guoliang Li, Fan Li, Xuzhi Li, Runduo Liang, Zheyu Lin, Qingzhong Liu, Wenhao Liu, Zhengyan Liu, Wei Liu, Yao Liu, Zheng Lou, Han Qu, Zhenfeng Sheng, Jianchun Shi, Yiping Shu, Zhenbo Su, Tianrui Sun, Hongchi Wang, Huiyuan Wang, Jian Wang, Junxian Wang, Daming Wei, Junjie Wei, Yongquan Xue, Jingzhi Yan, Chao Yang, Ye Yuan, Yefei Yuan, Hongxin Zhang, Miaomiao Zhang, Haibin Zhao, Wen Zhao
Summary: The Wide Field Survey Telescope (WFST) is a dedicated photometric surveying facility being built jointly by University of Science and Technology of China (USTC) and the Purple Mountain Observatory (PMO). It is equipped with a 2.5-meter diameter primary mirror and a mosaic CCD camera, and it will scan the northern sky in four optical bands to detect transient phenomena and study the variability of Galactic and extragalactic objects.
SCIENCE CHINA-PHYSICS MECHANICS & ASTRONOMY
(2023)
Article
Astronomy & Astrophysics
Maria Petronikolou, Emmanuel N. Saridakis
Summary: In this study, we investigate scalar-tensor and bi-scalar-tensor modified theories of gravity that can alleviate the H-0 tension. We show that by choosing particular models with specific features, such as a shift-symmetric friction term or phantom behavior of the effective dark-energy equation-of-state parameter, the tension can be alleviated. These theories provide known mechanisms for alleviating the H0 tension.
Article
Astronomy & Astrophysics
Shreya Banerjee, Maria Petronikolou, Emmanuel N. Saridakis
Summary: We investigate the cosmological applications of gravitational scalar-tensor theories and analyze them in the context of the H0 tension. Two specific models are explored, showing negligible effects at high redshifts but an increasing deviation as time passes. At low redshifts, the Hubble parameter takes on higher values in a controlled manner. This behavior is attributed to the phantom nature of the effective dark-energy equation-of-state parameter, providing a possible solution to the H0 tension. Comparison with cosmic chronometer data demonstrates full agreement within 1σ confidence level.
Article
Astronomy & Astrophysics
Petros Asimakis, Spyros Basilakos, Andreas Lymperis, Maria Petronikolou, Emmanuel N. Saridakis
Summary: This study constructs new classes of modified theories that couple the matter sector with the Einstein tensor, specifically considering direct couplings to the energy-momentum tensor and its trace derivatives. The general field equations, without higher-order derivatives, are derived and applied in a cosmological framework, resulting in Friedmann equations with additional terms that give rise to an effective dark energy sector. The study shows successful description of the thermal history of the universe at the background level, with matter and dark energy epochs, and the dark energy equation-of-state parameter can approach -1 as time progresses. Comparison with cosmic chronometer data demonstrates a very good agreement. Detailed investigations of scalar and tensor perturbations validate the predicted behavior of the matter overdensity.
Article
Chemistry, Multidisciplinary
Mita Dutta, Shreya Banerjee, Mahitosh Mandal, Manish Bhattacharjee
Summary: A self-healable metallohydrogel of Mn(ii) has been successfully prepared using a low molecular weight gelator, Na2HL. It has been characterized by various techniques and encapsulated with drugs IND and GEM. The GEM-loaded metallogel showed enhanced delivery and cytotoxicity against breast cancer cells, while the MOG_IND exhibited improved anti-inflammatory response compared to the drug alone.
Article
Astronomy & Astrophysics
Wompherdeiki Khyllep, Jibitesh Dutta, Emmanuel N. Saridakis, Kuralay Yesmakhanova
Summary: Motivated by the success of f(Q) gravity in fitting observational data, we analyze the behavior of two studied f(Q) models, power-law and exponential, through dynamical system analysis. We find that both models have a matter-dominated saddle point followed by a stable dark-energy-dominated accelerated universe. The models fit observational data well and can be considered as promising alternatives to the ACDM concordance model.
Article
Physics, Particles & Fields
Sebastian Bahamonde, Konstantinos F. Dialektopoulos, Manuel Hohmann, Jackson Levi Said, Christian Pfeifer, Emmanuel N. Saridakis
Summary: This study focuses on the cosmological perturbation theory in f(T) gravity, which is a simple extension of the teleparallel equivalent of general relativity. The authors examine the possibility of a non-flat FLRW background solution and perform perturbations for different spatial geometries. They determine the behavior of the perturbative modes in this non-flat FLRW setting for arbitrary f(T) models and identify propagating modes.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Astronomy & Astrophysics
Lei-Hua Liu, Mian Zhu, Wentao Luo, Yi-Fu Cai, Yi Wang
Summary: We systematically investigate the microlensing effect of a charged spherically symmetric wormhole, where the light source is remote from the throat. The numerical result shows that the range of total magnification is from 105 to 10-2 depending on various metrics. Our theoretical investigation could shed new light on exploring the wormhole with the microlensing effect.
Article
Astronomy & Astrophysics
Yu-Min Hu, Yaqi Zhao, Xin Ren, Bo Wang, Emmanuel N. Saridakis, Yi-Fu Cai
Summary: This study investigates the scalar perturbations and possible strong coupling issues of f(T) gravity using the effective field theory (EFT) approach. The generalized EFT framework of modified teleparallel gravity is revisited and applied to examine both linear and second-order perturbations in f(T) theory. The results suggest that there is no new scalar mode present in f(T) gravity, indicating a strong coupling problem. However, an estimation of the strong coupling scale based on the ratio of cubic to quadratic Lagrangians shows that the strong coupling problem can be avoided for certain modes.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Nelson R. F. Braga, Octavio C. Junqueira
Summary: This study investigates the influence of rotation on the transition temperature of strongly interacting matter produced in non-central heavy ion collisions. By using a holographic description of an AdS black hole, the authors extend the analysis to the more realistic case where the matter spreads over a region around the rotational axis. The results show the coexistence of confined and deconfined phases and are consistent with the concept of local temperature in rotating frames developed by Tolman and Ehrenfest.
Article
Astronomy & Astrophysics
Bing Sun, Jiachen An, Zhoujian Cao
Summary: This paper investigates the effect of gravitational constant variation on the propagation of gravitational waves. By employing two analytical methods, the study finds that variations in the gravitational constant result in amplitude and phase corrections for gravitational waves, and the time variation of the gravitational constant can be constrained through the propagation of gravitational waves.
Article
Astronomy & Astrophysics
Abdellah Touati, Zaim Slimane
Summary: This letter presents the first study of Hawking radiation as a tunneling process within the framework of non-commutative gauge theory of gravity. The non-commutative Schwarzschild black hole is reconstructed using the Seiberg-Witten map and the star product. The emission spectrum of outgoing massless particles is computed using the quantum tunneling mechanism. The results reveal pure thermal radiation in the low-frequency scenario, but a deviation from pure thermal radiation in the high-frequency scenario due to energy conservation. It is also found that noncommutativity enhances the correlations between successively emitted particles.
Article
Astronomy & Astrophysics
Shahar Hod
Summary: The travel times of light signals between two antipodal points on a compact star's surface are calculated for two different trajectories. It is shown that, for highly dense stars, the longer trajectory along the surface may have a shorter travel time as measured by asymptotic observers. A critical value of the dimensionless density-area parameter is determined for constant density stars to distinguish cases where crossing through the star's center or following a semi-circular trajectory on the surface has a shorter travel time as measured by asymptotic observers.
