Article
Astronomy & Astrophysics
Justin Khoury, Sam S. C. Wong
Summary: This research explores the possibility of our existence in the early stages of the universe, proposing an early-time measure for vacuum systems that favors short-lived vacua, funneled regions, and small positive vacuum energy. It also draws an analogy to protein folding energy landscapes.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Nahomi Kan, Takuma Aoyama, Kiyoshi Shiraishi
Summary: This paper examines a bicosmology scenario proposed by Falomir et al., which introduces noncommutativity to solve cosmological problems. By considering exact classical solutions with constant noncommutativity and hypothesizing the appearance of noncommutativity when the scale factors are small, the researchers investigate the behavior of the model.
CLASSICAL AND QUANTUM GRAVITY
(2023)
Article
Astronomy & Astrophysics
Shang Li, Ji-Ping Dai, Xiu-Hui Tan, Yang-Jie Yan, Jun-Qing Xia
Summary: The bounce scenario in cosmology is a research topic that addresses the singularity problem and trans-Planckian issue left by the standard inflationary theory. In this work, the authors extend the analysis to large-scale structure measurements and find that the model parameters can be constrained effectively. The constraints become even stronger when combined with the measurements from the Planck satellite.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Ido Ben-Dayan, Utkarsh Kumar, Udaykrishna Thattarampilly, Amresh Verma
Summary: In this study, the NANOGrav signal on stochastic gravitational wave background is analyzed and the Universe's reheating phase is constrained using the latest measurements from NANOGrav. The analysis reveals a preference for instant reheating and a very blue tilt in the tensor spectrum. Additionally, a degeneracy between the tensor-to-scalar ratio and reheating temperature is found, with suggestions on ways to break this degeneracy.
Article
Astronomy & Astrophysics
Hugo Garcia-Compean, Octavio Obregon, Cupatitzio Ramirez
Summary: This article reviews the work done by the authors and collaborators in the fields of supersymmetric quantum cosmology, noncommutative quantum cosmology, and the application of generalized uncertainty principles to quantum cosmology and black holes. The review is presented in chronological order and reflects the authors' personal views on the subjects.
Article
Astronomy & Astrophysics
Steffen Gielen, Axel Polaczek
Summary: The author extends the construction of Hamiltonian group field theory to models with multiple scalar matter fields, finding that the effective cosmological dynamics reduce to the Friedmann dynamics of general relativity with multiple scalar fields in the limit of large volume. At high energy, corrections to the classical Friedmann equations are found, leading to generic singularity resolution by a bounce. Additionally, the effective cosmological dynamics treat the clock field and other matter fields differently for generic initial conditions, in disagreement with the Friedmann dynamics of general relativity.
Article
Physics, Multidisciplinary
G. Oliveira-Neto, L. Fazza Marcon
Summary: The study explores the accelerated expansion of the universe by introducing noncommutativity in a Friedmann-Robertson-Walker cosmological model. The noncommutative model is found to effectively describe the expansion of the universe.
EUROPEAN PHYSICAL JOURNAL PLUS
(2021)
Article
Physics, Multidisciplinary
G. A. Monerat, F. G. Alvarenga, S. V. B. Goncalves, G. Oliveira-Neto, C. G. M. Santos, E. Correa Silva
Summary: This study analyzes the effects of quantization on a Friedmann-Lemaitre-Robertson-Walker model with positive curvature and material content composed of a radiation fluid and a cosmological constant. The results show that bounce solutions can be obtained, with exits for inflation, by introducing a cosmological constant and a specific potential term.
EUROPEAN PHYSICAL JOURNAL PLUS
(2022)
Article
Astronomy & Astrophysics
Chia -Min Lin
Summary: In this paper, we revisit D-term inflation and provide bounds on the cosmic string tension using gravitational wave observations. We also consider the possible deviation of the spectral index compared with the ΛCDM model in light of prerecombination resolutions of the Hubble tension. Our study shows that D-term inflation requires very small coupling constants under these constraints, and we demonstrate that natural coupling constants (g = A = 0.1) can be achieved in the case of D-term inflation on the brane.
Article
Astronomy & Astrophysics
Gabriel Alvarez, Luis Martinez Alonso, Elena Medina
Summary: This study analyzes the emergence of classical inflationary universes during a kinetic-dominated stage, using a suitable class of solutions from the Wheeler-DeWitt equation. By utilizing these solutions along with the solutions from the classical model, specific instances of wave functions can be obtained.
Article
Physics, Particles & Fields
Adam Balcerzak, Mateusz Lisaj
Summary: This paper investigates quantized bi-scalar gravity as a locally Lorentz invariant cosmological model. It demonstrates that specific cosmogenesis and the transition from pre-big-bang contraction to post-big-bang expansion can occur due to the action of symmetry transformations, such as unitary or antiunitary transformations. The role of charge conjugation and a unitary transformation resembling the Hadamard gate are also discussed.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Astronomy & Astrophysics
Martin Bojowald, Ari Gluckman
Summary: A recent study shows that a tunneling universe model exhibits chaotic dynamics through the analysis of fractal dimensions in the plane of initial values. This result is based on non-adiabatic features of quantum dynamics captured by new quasiclassical methods. The chaotic dynamics in the early universe, described by such models, allows for a larger range of initial values to be probed.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Eleonora Giovannetti, Gabriele Barca, Federico Mandini, Giovanni Montani
Summary: In this paper, we analyze the semiclassical and quantum polymer dynamics of the isotropic Universe using both the standard and new generalized coordinates. We study the properties of the bouncing cosmology in both representations and show that the Big Bounce is a fundamental cutoff on the cosmological dynamics when the volume variable is implemented. However, when using the standard connection, the energy density of the Universe Bounce is fixed by the initial conditions.
Article
Astronomy & Astrophysics
Nina S. Sartorio, A. Fialkov, T. Hartwig, G. M. Mirouh, R. G. Izzard, M. Magg, R. S. Klessen, S. C. O. Glover, L. Chen, Y. Tarumi, D. D. Hendriks
Summary: The properties of X-ray binaries (XRBs) arising from zero metallicity stars and their dependence on the initial mass function (IMF) of primordial stars are explored in this study. The results show that the IMF has a strong effect on the number and X-ray production efficiency of XRBs. Scaling relations between XRBs and their X-ray emission with the local star formation rate are also presented. The findings provide insights for improving X-ray feedback prescriptions in numerical simulations.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Review
Physics, Nuclear
Marc Kamionkowski, Adam G. Riess
Summary: Over the past decade, the disparity between the directly measured cosmic expansion rate and the rate determined from the standard Lambda CDM cosmological model has increased, leading to the need for a solution. Proposed systematic errors are not supported by the available data, making it difficult to find simple theoretical explanations for this Hubble tension. Recent attention has focused on models that alter the early physics of Lambda CDM as the most feasible solution.
ANNUAL REVIEW OF NUCLEAR AND PARTICLE SCIENCE
(2023)
Article
Astronomy & Astrophysics
G. A. Monerat, E. V. Correa Silva, C. Neves, G. Oliveira-Neto, L. G. Rezende Rodrigues, M. Silva de Oliveira
INTERNATIONAL JOURNAL OF MODERN PHYSICS D
(2017)
Article
Astronomy & Astrophysics
G. Oliveira-Neto, L. G. Martins, G. A. Monerat, E. V. Correa Silva
MODERN PHYSICS LETTERS A
(2018)
Article
Computer Science, Interdisciplinary Applications
E. V. Correa Silva, G. A. Monerat, G. de Oliveira Neto, L. G. Ferreira Filho
COMPUTER PHYSICS COMMUNICATIONS
(2014)
Article
Physics, Multidisciplinary
G. Oliveira-Neto, G. A. Monerat, E. V. Correa Silva, C. Neves, L. G. Ferreira Filho
INTERNATIONAL JOURNAL OF THEORETICAL PHYSICS
(2013)
Article
Physics, Multidisciplinary
G. A. Monerat, L. G. Ferreira Filho, G. Oliveira-Neto, E. V. Correa Silva, C. Neves
Article
Astronomy & Astrophysics
G. Oliveira-Neto, L. G. Martins, G. A. Monerat, E. V. Correa Silva
INTERNATIONAL JOURNAL OF MODERN PHYSICS D
(2019)
Article
Astronomy & Astrophysics
R. C. Freitas, G. A. Monerat, G. Oliveira-Neto, F. G. Alvarenga, S. V. B. Goncalves, R. Fracalossi, E. Correa Silva, L. G. Ferreira Filho
PHYSICS OF THE DARK UNIVERSE
(2019)
Article
Physics, Multidisciplinary
G. A. Monerat, C. G. M. Santos, F. G. Alvarenga, S. V. B. Goncalves, R. Fracalossi, E. Correa Silva, G. Oliveira-Neto
BRAZILIAN JOURNAL OF PHYSICS
(2020)
Article
Physics, Multidisciplinary
G. A. Monerat, C. G. M. Santos, G. Oliveira-Neto, E. V. Correa Silva, L. G. Ferreira Filho
Summary: The study focuses on quantizing the dynamics of the early universe and numerically solving for the time evolution of the wave function and tunneling probability. The results suggest that the universe should nucleate with the highest values of energy and parameters, and may enter an inflationary phase afterwards.
EUROPEAN PHYSICAL JOURNAL PLUS
(2021)
Article
Physics, Multidisciplinary
G. A. Monerat, F. G. Alvarenga, S. V. B. Goncalves, G. Oliveira-Neto, C. G. M. Santos, E. Correa Silva
Summary: This study analyzes the effects of quantization on a Friedmann-Lemaitre-Robertson-Walker model with positive curvature and material content composed of a radiation fluid and a cosmological constant. The results show that bounce solutions can be obtained, with exits for inflation, by introducing a cosmological constant and a specific potential term.
EUROPEAN PHYSICAL JOURNAL PLUS
(2022)
Article
Physics, Multidisciplinary
G. Oliveira-Neto, D. L. Canedo, G. A. Monerat
Summary: In this study, we investigated the dynamical evolution of a homogeneous and anisotropic cosmological model, considering general relativity and three different perfect fluids in the matter sector. We found that the universe tends to become isotropic during its expansion, suggesting an initial anisotropic stage that later became isotropic.
BRAZILIAN JOURNAL OF PHYSICS
(2022)
Article
Physics, Multidisciplinary
N. M. N. da Rocha, G. A. Monerat, F. G. Alvarenga, S. V. B. Goncalves, G. Oliveira-Neto, E. Correa Silva, C. G. M. Santos
Summary: In this study, we analyzed the quantum dynamics and emergence mechanism of the inflationary phase in the Planck era. We numerically quantized a model composed of dust and Chaplygin gas, and calculated the quantum tunneling probabilities. The results showed that models with dust have a higher probability of tunneling compared to models with radiation, indicating that universes with Chaplygin gas and dust are more likely to exist.
EUROPEAN PHYSICAL JOURNAL PLUS
(2022)
Article
Physics, Multidisciplinary
G. A. Monerat, O. Goldoni, F. G. Alvarenga, G. Oliveira-Neto, E. Correa Silva
Summary: This work presents a quantum cosmological Einstein aether model obtained using the Schutz variational formalism. The model describes a spatially flat Universe filled with a barotropic fluid with a specific equation of state. Solutions to the Wheeler-DeWitt equation are obtained through the superposition of stationary quantum states, resulting in finite-norm wave packets. The behavior of the scale factor is studied from the perspectives of many-worlds and de Broglie-Bohm interpretations, indicating the existence of non-singular solutions for certain conditions.
EUROPEAN PHYSICAL JOURNAL PLUS
(2022)
Article
Physics, Multidisciplinary
F. G. Alvarenga, L. A. M. Diniz, S. V. B. Goncalves, G. A. Monerat, E. V. Correa Silva
Summary: In this study, a classical cosmological model based on a modified theory of gravitation is presented. The ADM formalism is used to incorporate the Einstein-Aether theory, which couples a timelike vector field to the metric, and the Schutz formalism is introduced to describe the material content of the Universe as a perfect baryonic fluid. The Wheeler-DeWitt quantization scheme is then applied to obtain the wave function of the Universe. The study explores the many-worlds interpretation and the de Broglie-Bohm interpretation of quantum mechanics, showing the possibility of avoiding a singularity at the beginning of the Universe.
EUROPEAN PHYSICAL JOURNAL PLUS
(2023)