Article
Astronomy & Astrophysics
Amjad Ashoorioon, Ghazal Geshnizjani, Hyung J. Kim
Summary: In this paper, we study the validity and non-Gaussianity of Extended Effective Field Theory of Inflation (EEFToI) with initial conditions set with dispersion relations omega(2) a k(6). By computing the bispectrum and investigating the shape of triangles, we find interesting regions of parameter space where EEFToI with these initial conditions is sensible.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Fengge Zhang, Yungui Gong, Jiong Lin, Yizhou Lu, Zhu Yi
Summary: The study of non-Gaussianities of primordial curvature perturbations in G-inflation models reveals that even though f(NL) becomes large at certain scales, it remains to be small at peak scales. This suggests that the contributions of non-Gaussianity to scalar induced secondary gravitational waves and primordial black hole abundance are expected to be negligible.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Harry Goodhew, Sadra Jazayeri, Mang Hei Gordon Lee, Enrico Pajer
Summary: This paper discusses the initial conditions of the universe and the impact of quantum mechanics on late-time observables, deriving a set of single-cut rules, discussing the analytical structure of the wave function, and verifying the applicability of these rules in some specific examples.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Lucas Pinol
Summary: This article explores linear dynamics and cubic interactions for N-field scalar fields during inflation, using observable curvature perturbations and entropic fluctuations. It reveals rich geometrical effects beyond scalar curvature, particularly when the field space dimension is larger than two. The article also highlights potential instability in background dynamics when N-field is greater than or equal to 3, due to negative eigenvalues in the entropic mass matrix from fast rotation of local entropic basis.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Arunoday Sarkar, Chitrak Sarkar, Buddhadeb Ghosh
Summary: By defining the k-modes of quantum fluctuations during inflation through the dynamical horizon crossing condition k = aH, and solving the equations of cosmological first-order perturbations self-consistently with chaotic alpha-attractor type potentials, we were able to study the behavior of various parameters in k-space. Comparison with Planck data in the low-k regime constrained the values of the alpha parameter through microscopic calculations. The calculated results matched the Planck-2018 data with 68% or near 95% CL for various values of alpha.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Emanuela Dimastrogiovanni, Matteo Fasiello, A. Emir Gumrukcuoglu
Summary: This paper investigates the possibility of extra spinning particles during inflation, focusing on the spin-2 case. The study explores the parameter space of the inflationary Lagrangian and identifies regions with signatures detectable by upcoming CMB probes. The analysis reveals the presence of a local-type non-Gaussianity in the gravitational wave spectrum and three-point function, which may be within the sensitivity range of both LiteBIRD and CMB-S4 experiments.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Sabino Matarrese, Luigi Pilo, Rocco Rollo
Summary: By carefully implementing gauge transformations involving long-wavelength modes, it is shown that effects involving squeezed bispectrum configurations cannot be gauged away, except for the unphysical exactly infinite-wavelength limit. This result is particularly relevant for the Maldacena consistency relation for single-field inflation and the f(NL)(GR) = -5/3 term appearing in dark matter bispectrum and halo bias, indicating their physical and observable nature in principle.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Jason Kristiano, Jun'ichi Yokoyama
Summary: By calculating the one-loop correction to the two-point functions of curvature perturbation in single-field inflation generated by cubic self-interaction, we find that the correction is finite and inversely proportional to the spectral tilt. Requiring the correction to be much smaller than the tree-level contribution leads to an upper bound on primordial non-Gaussianity. Observationally, the allowed region of non-Gaussian parameter space is entirely included by the region where the one-loop correction is smaller than the tree-level contribution, but there exists a significantly large region where the one-loop correction is larger than 1% or even 10% of the latter. If future observations confirm non-Gaussianity falling within such a region, it would be important to incorporate higher-order corrections to the spectrum in order to achieve precise cosmology. In some extreme cases, where the one-loop correction has a comparable magnitude to the tree-level contribution, it might indicate a breakdown of the cosmological perturbation theory in the context of single-field inflation.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Enrico Pajer
Summary: The study focuses on the three-point correlators of gravitons and scalar curvature perturbations around a quasi de Sitter space-time and establishes Bootstrap Rules that fully fix the form of these correlators in the asymptotic future at the boundary. The Boostless Bootstrap approach is shown to account for the breaking of de Sitter boosts caused by inflationary backgrounds. Derivations of bispectra involving gravitons in single-clock, canonical inflation are easily derived in this approach, as well as the scalar bispectrum in the Effective Field Theory of inflation to any order in derivatives. In many cases, the derivations are computationally simpler than the corresponding explicit calculations, emphasizing the implications of locality, vacuum choice, and underlying symmetries.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Sam Young
Summary: In this study, we reassess the impact of local-type non-Gaussianity on the abundance of primordial black holes (PBHs) and find that the effect is much less significant than previously believed. The non-Gaussianity parameters need to be significantly larger to have a similar effect as before, which weakens the constraints on PBH abundance and the primordial power spectrum dependence on non-Gaussianity parameters. Furthermore, we question the existing calculations of PBH abundance due to the correlation between curvature perturbation and compaction.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Raphal van Laak, Sam Young
Summary: Primordial black holes are black holes that may have formed in high density regions in the early universe. The fluctuations in their formation rate can be used to constrain the amplitude of non-Gaussianity, especially if primordial black holes make up a significant fraction of dark matter. By extending the calculation to include peaks theory and considering the non-linearities between compaction C and curvature perturbation C, we find that the constraints on quadratic models of non-Gaussianity are largely unchanged, while the constraints on cubic models significantly worsen. If all of the dark matter is composed of primordial black holes, the parameters of non-Gaussianity are -2.9 & BULL; 10-4 < f < 3.8 & BULL; 10-4 and -1.5 & BULL; 10-3 < g < 1.9 & BULL; 10-3 for quadratic and cubic models respectively.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Dong-Gang Wang, Guilherme L. Pimentel, Ana Achucarro
Summary: Primordial non-Gaussianities from multi-field inflation are studied in this paper, with a focus on the nonlinear conversion process from additional light scalars into curvature perturbations. Analytic templates for correlation functions at any kinematical configuration are provided using the cosmological bootstrap. The results include the possibility of large breaking of boost symmetry and small speeds of sound for both the inflaton and the mediators. The symmetry constraints on the correlators are found to be modified by introducing a late-time cutoff, leading to anomalous conformal Ward identities.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Damiano Anselmi
Summary: This study investigates primordial cosmology with two scalar fields participating in inflation, revealing the existence of an asymptotically de Sitter cosmic RG flow in two couplings. The importance of quantum gravity theory's predictiveness and the role of RG invariance are highlighted.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
William Giare, Fabrizio Renzi, Olga Mena, Eleonora Di Valentino, Alessandro Melchiorri
Summary: The Data Release 4 of the Atacama Cosmology Telescope (ACT) shows an agreement with a Harrison-Zel'dovich primordial spectrum, introducing a tension with the results from the Planck satellite. This discrepancy on the value of the scalar spectral index is not alleviated with the addition of large scale structure information or low multipole polarization data. Possible avenues to alleviate the tension are discussed, including neglecting polarization measurements from ACT or extending different sectors of the theory.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Kareem Marzouk, Alessandro Maraio, David Seery
Summary: In this study, we update predictions for observables in the "delicate" D3/(D3) over bar inflationary model on the conifold. Our analysis shows that the model can accurately forecast the amplitude of three-point correlations. The model generally follows Maldacena's single-field prediction, but in some cases, the bispectrum is dominated by effects from rapid switching between angular minima, resulting in larger amplitudes but with unacceptable spectral behavior.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Guilherme Brando, Kazuya Koyama, David Wands
Summary: This study presents a method to introduce relativistic corrections into Horndeski theory in numerical simulations, assuming gravitational coupling only between standard matter species and the scalar field. The impact of relativistic corrections on the matter power spectrum in k-essence models, including massless and massive neutrinos, is investigated, with results showing a maximum deviation of approximately 7% at k similar to 10(-3) Mpc(-1) at z = 0. The formalism developed in this study allows for testing beyond ΛCDM models using upcoming large-scale structure surveys.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Andrius Tamosiunas, Hans A. Winther, Kazuya Koyama, David J. Bacon, Robert C. Nichol, Ben Mawdsley
Summary: The study employed various techniques commonly used in machine learning literature to address the limitations of GAN approach. They trained a GAN to produce weak lensing convergence maps and dark matter overdensity field data for multiple redshifts, cosmological parameters, and modified gravity models. Additionally, they trained a GAN using the newest Illustris data to simultaneously emulate dark matter, gas, and internal energy distribution data. Finally, they applied the technique of latent space interpolation to generate outputs with intermediate cosmological parameters that were not included in the training data.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Shadab Alam, Christian Arnold, Alejandro Aviles, Rachel Bean, Yan-Chuan Cai, Marius Cautun, Jorge L. Cervantes-Cota, Carolina Cuesta-Lazaro, N. Chandrachani Devi, Alexander Eggemeier, Sebastien Fromenteau, Alma X. Gonzalez-Morales, Vitali Halenka, Jian-hua He, Wojciech A. Hellwing, Cesar Hernandez-Aguayo, Mustapha Ishak, Kazuya Koyama, Baojiu Li, Axel de la Macorra, Jennifer Meneses Rizo, Christopher Miller, Eva-Maria Mueller, Gustavo Niz, Pierros Ntelis, Matia Rodriguez Otero, Cristiano G. Sabiu, Zachary Slepian, Alejo Stark, Octavio Valenzuela, Georgios Valogiannis, Mariana Vargas-Magana, Hans A. Winther, Pauline Zarrouk, Gong-Bo Zhao, Yi Zheng
Summary: This paper studies the predictions of two modified gravity models beyond linear redshift distortions using N-body simulations and mock galaxy catalogs, finding promising power for testing GR. A major challenge for the future is to create realistic mock galaxy catalogs for both GR and alternative models to fully utilize the statistic power of the DESI survey and understand the impact of systematic effects.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Jamie Donald-McCann, Florian Beutler, Kazuya Koyama, Minas Karamanis
Summary: MATRYOSHKA is a suite of neural-network-based emulators and accompanying python package that can provide fast and accurate predictions of the non-linear galaxy power spectrum. By combining linear component emulators with a non-linear boost component emulator, it is possible to predict the real space non-linear galaxy power spectrum with high accuracy.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Jinglan Zheng, Gong-Bo Zhao, Yuting Wang, Xiaoyong Mu, Ruiyang Zhao, Weibing Zhang, Shuo Yuan, David Bacon, Kazuya Koyama
Summary: A new consistency test is proposed to validate the ?CDM cosmology using baryonic acoustic oscillations (BAO) and redshift space distortion (RSD) measurements. The test compares the predicted peak position of f sigma (8)(z) based on BAO observables with the peak position offered by RSD measurements. The test is demonstrated using simulated data from the DESI galaxy survey and is argued to complement existing methods and be less susceptible to systematics in RSD analysis.
RESEARCH IN ASTRONOMY AND ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Guilherme Brando, Bartolomeo Fiorini, Kazuya Koyama, Hans A. Winther
Summary: In this study, we compare and validate COLA simulations against existing emulators in the literature, and find that COLA method shows excellent agreement with the emulators under certain conditions. Furthermore, the implementation of massive neutrinos in COLA simulations and the ability to handle effective field theory of dark energy and modified gravity models are validated through experiments.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Joseph H. P. Jackson, Hooshyar Assadullahi, Kazuya Koyama, Vincent Vernin, David Wands
Summary: This article demonstrates the usage of importance sampling for reconstructing the statistics of rare cosmological fluctuations in stochastic inflation. The authors developed a publicly available package, PYFPT, that addresses the first-passage time problem of generic one-dimensional Langevin processes and its relation to curvature perturbation. The proposed method is applied to quadratic inflation and benchmarked against semi-analytical results, showing excellent agreement within the estimated statistical error. The computation time is relatively fast and can achieve low probability values compared to the observable universe. The study also investigates the impact of large-field boundaries on the tail of the probability distribution and demonstrates that non-perturbative deviations from Gaussianity are not always of the simple exponential type.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
A. Emir Gumrukcuoglu, Kazuya Koyama
Summary: We argue that cubic order interactions between scalar and tensor gravitons play crucial roles in the decay of gravitational waves and the gradient instabilities of scalar perturbations. However, the existence of an infinite number of higher order interactions in generic Λ³ models makes it difficult to predict the fate of these instabilities.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Levon Pogosian, Marco Raveri, Kazuya Koyama, Matteo Martinelli, Alessandra Silvestri, Gong-Bo Zhao, Jian Li, Simone Peirone, Alex Zucca
Summary: This study explores modifications of the standard cold dark matter cosmological model and identifies the necessary features for alternative theories to alleviate tensions between cosmological datasets. The results provide important constraints on modified gravity models and suggest that late-time dynamical dark energy and modifications of gravity may not offer a solution to certain tensions.
Article
Astronomy & Astrophysics
Bartolomeo Fiorini, Kazuya Koyama, Albert Izard
Summary: This study investigates the effects of two Modified Gravity (MG) theories on large-scale structure and validates the accuracy of fast approximate COLA simulations in predicting these effects. The results show that using the first three even multipoles of the redshift space power spectrum is sufficient to reproduce the influence of MG theories on the real space power spectrum. Additionally, the study highlights the importance of considering non-linear contributions and suggests that the effects of MG theories on the bispectrum and voids can be dominated by non-linear galaxy bias.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Physics, Multidisciplinary
A. D. Gow, H. Assadullahi, J. H. P. Jackson, K. Koyama, V. Vennin, D. Wands
Summary: We propose a non-perturbative method to calculate the abundance of primordial black holes based on an arbitrary one-point probability distribution function for the primordial curvature perturbation, P(zeta). This method is essential for considering non-Gaussianities that cannot be treated using conventional perturbative expansions. By relating zeta to a Gaussian field through equating cumulative distribution functions, we can determine the full statistics of the density field. We demonstrate that the intermediate regime, rather than the far tail, is responsible for the enhanced formation of primordial black holes, and show that non-Gaussianity significantly affects the shape of the primordial black hole mass distribution.
Article
Astronomy & Astrophysics
Guilherme Brando, Kazuya Koyama, Hans A. Winther
Summary: We revisit and extend a method proposed by R. Scoccimarro to incorporate the Vainshtein screening mechanism in N-body simulations, allowing for the study of Horndeski theories that evade the speed limit on gravitational waves. The method computes a scale-dependent gravitational coupling that accounts for the screening of the fifth-force, significantly reducing computational time and complexity compared to solving the full equation of motion. By implementing this method in a COmoving Lagrangian Approximation (COLA) code and comparing it with full N-body simulations, we validate its accuracy and find high agreement for the prediction of the boost function, a crucial quantity for beyond-ACDM models.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Marco Raveri, Levon Pogosian, Matteo Martinelli, Kazuya Koyama, Alessandra Silvestri, Gong -Bo Zhao
Summary: In this paper, a non-parametric reconstruction method is presented to determine three time-dependent functions in the cosmological model. The data constraints on the structure of these functions and their eigenmodes are analyzed. The results show that the combination of all data can constrain 15 combined eigenmodes of the three functions and explain the tensions between datasets.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Review
Physics, Particles & Fields
Pierre Auclair, David Bacon, Tessa Baker, Tiago Barreiro, Nicola Bartolo, Enis Belgacem, Nicola Bellomo, Ido Ben-Dayan, Daniele Bertacca, Marc Besancon, Jose J. Blanco-Pillado, Diego Blas, Guillaume Boileau, Gianluca Calcagni, Robert Caldwell, Chiara Caprini, Carmelita Carbone, Chia-Feng Chang, Hsin-Yu Chen, Nelson Christensen, Sebastien Clesse, Denis Comelli, Giuseppe Congedo, Carlo Contaldi, Marco Crisostomi, Djuna Croon, Yanou Cui, Giulia Cusin, Daniel Cutting, Charles Dalang, Valerio De Luca, Walter Del Pozzo, Vincent Desjacques, Emanuela Dimastrogiovanni, Glauber C. Dorsch, Jose Maria Ezquiaga, Matteo Fasiello, Daniel G. Figueroa, Raphael Flauger, Gabriele Franciolini, Noemi Frusciante, Jacopo Fumagalli, Juan Garcia-Bellido, Oliver Gould, Daniel Holz, Laura Iacconi, Rajeev Kumar Jain, Alexander C. Jenkins, Ryusuke Jinno, Cristian Joana, Nikolaos Karnesis, Thomas Konstandin, Kazuya Koyama, Jonathan Kozaczuk, Sachiko Kuroyanagi, Danny Laghi, Marek Lewicki, Lucas Lombriser, Eric Madge, Michele Maggiore, Ameek Malhotra, Michele Mancarella, Vuk Mandic, Alberto Mangiagli, Sabino Matarrese, Anupam Mazumdar, Suvodip Mukherjee, Ilia Musco, Germano Nardini, Jose Miguel No, Theodoros Papanikolaou, Marco Peloso, Mauro Pieroni, Luigi Pilo, Alvise Raccanelli, Sebastien Renaux-Petel, Arianna I. Renzini, Angelo Ricciardone, Antonio Riotto, Joseph D. Romano, Rocco Rollo, Alberto Roper Pol, Ester Ruiz Morales, Mairi Sakellariadou, Ippocratis D. Saltas, Marco Scalisi, Kai Schmitz, Pedro Schwaller, Olga Sergijenko, Geraldine Servant, Peera Simakachorn, Lorenzo Sorbo, Lara Sousa, Lorenzo Speri, Daniele A. Steer, Nicola Tamanini, Gianmassimo Tasinato, Jesus Torrado, Caner Unal, Vincent Vennin, Daniele Vernieri, Filippo Vernizzi, Marta Volonteri, Jeremy M. Wachter, David Wands, Lukas T. Witkowski, Miguel Zumalacarregui, James Annis, Feanor Reuben Ares, Pedro P. Avelino, Anastasios Avgoustidis, Enrico Barausse, Alexander Bonilla, Camille Bonvin, Pasquale Bosso, Matteo Calabrese, Mesut Caliskan, Jose A. R. Cembranos, Mikael Chala, David Chernoff, Katy Clough, Alexander Criswell, Saurya Das, Antonio da Silva, Pratika Dayal, Valerie Domcke, Ruth Durrer, Richard Easther, Stephanie Escoffier, Sandrine Ferrans, Chris Fryer, Jonathan Gair, Chris Gordon, Martin Hendry, Mark Hindmarsh, Deanna C. Hooper, Eric Kajfasz, Joachim Kopp, Savvas M. Koushiappas, Utkarsh Kumar, Martin Kunz, Macarena Lagos, Marc Lilley, Joanes Lizarraga, Francisco S. N. Lobo, Azadeh Maleknejad, C. J. A. P. Martins, P. Daniel Meerburg, Renate Meyer, Jose Pedro Mimoso, Savvas Nesseris, Nelson Nunes, Vasilis Oikonomou, Giorgio Orlando, Ogan Ozsoy, Fabio Pacucci, Antonella Palmese, Antoine Petiteau, Lucas Pinol, Simon Portegies Zwart, Geraint Pratten, Tomislav Prokopec, John Quenby, Saeed Rastgoo, Diederik Roest, Kari Rummukainen, Carlo Schimd, Aurelia Secroun, Alberto Sesana, Carlos F. Sopuerta, Ismael Tereno, Andrew Tolley, Jon Urrestilla, Elias C. Vagenas, Jorinde van de Vis, Rien van de Weygaert, Barry Wardell, David J. Weir, Graham White, Bogumila Swiezewska, Valery I. Zhdanov
Summary: This publication provides an overview of the latest advancements in LISA cosmology, including theory and methods, and identifies new opportunities to probe the universe using gravitational-wave observations by LISA.
LIVING REVIEWS IN RELATIVITY
(2023)
Article
Astronomy & Astrophysics
Matteo Braglia, Mario Ballardini, Fabio Finelli, Kazuya Koyama
Summary: The early modified gravity model proposed involves a scalar field with nonminimal coupling to the Ricci curvature, showing potential in alleviating the H-0 tension while fitting well with CMB anisotropies and BAO data. The scalar field in the model remains frozen in the radiation era, growing near matter-radiation equality and dampening into coherent oscillations due to a small effective mass induced by a quartic potential, ultimately leading to weaker gravitational strength at early times. Comparative analysis with other models suggests that this EMG model can significantly alleviate the H-0 tension when considering the full shape of the matter power spectrum in addition to CMB and SN data.