A5019666029- Cosmology and Gravitation Theories
- Black Holes and Theoretical Physics
- Galaxies: Formation, Evolution, Phenomena
- Relativity and Gravitational Theory
- Dark Matter and Cosmic Phenomena
- Solar and Space Plasma Dynamics
- Geophysics and Gravity Measurements
- Pulsars and Gravitational Waves Research
- Gamma-ray bursts and supernovae
- Astronomy and Astrophysical Research
- Radio Astronomy Observations and Technology
- Stellar, planetary, and galactic studies
- Neutrino Physics Research
- Astrophysics and Cosmic Phenomena
- Computational Physics and Python Applications
- Superconducting and THz Device Technology
- Advanced Frequency and Time Standards
- Particle physics theoretical and experimental studies
- Quantum Mechanics and Applications
- Model Reduction and Neural Networks
- Scientific Research and Discoveries
- Theoretical and Computational Physics
- Noncommutative and Quantum Gravity Theories
- Radioactive Decay and Measurement Techniques
- Stochastic processes and statistical mechanics
University of Buenos Aires
2014-2024
Consejo Nacional de Investigaciones Científicas y Técnicas
2013-2024
Fundación Ciencias Exactas y Naturales
2014-2024
Instituto de Física de Buenos Aires
2011-2024
Institute of Astronomy and Space Physics
2012-2023
Centro Científico Tecnológico - Tucumán
2003-2015
Instituto de Física La Plata
2011
Universidad Nacional de La Plata
1999-2008
We discuss observational constraints coming from CMB and type Ia supernovae for the model of an accelerated universe produced by gravitational leakage into extra dimensions. Our fits indicate that is currently in agreement with data. also give equations governing evolution cosmological perturbations. Future observations will be able to severely constrain model.
The Q $\&$ U Bolometric Interferometer for Cosmology (QUBIC) is a novel kind of polarimeter optimized the measurement B-mode polarization Cosmic Microwave Background (CMB), which one major challenges observational cosmology. signal expected to be order few tens nK, prone instrumental systematic effects and polluted by various astrophysical foregrounds can only controlled through multichroic observations. QUBIC designed address these issues with approach that combines advantages...
We briefly review an important shortcoming --unearthed in previous works-- of the standard version inflationary model for emergence seeds cosmic structure. consider here some consequences emerging from a proposal inspired on ideas Penrose and Di\'osi about quantum-gravity induced reduction wave function, which has been put forward to address shortcomings, arguing that its effect inflaton field is what can lead The leads deviation primordial spectrum scale-invariant Harrison-Zel'dovich one,...
The usual account for the origin of cosmic structure during inflation is not fully satisfactory, as it lacks a physical mechanism capable generating inhomogeneity and anisotropy our Universe, from an exactly homogeneous isotropic initial state associated with early inflationary regime. proposal in [A. Perez, H. Sahlmann, D. Sudarsky, Classical Quantum Gravity 23, 2317 (2006)] considers spontaneous dynamical collapse wave function possible answer to that problem. In this work, we review...
In the last few years, there has been significant progress in development of machine learning methods tailored to astrophysics and cosmology. We have recently applied one these, namely, neural network bundle method, cosmological scenario. Moreover, we showed that some cases computational times Bayesian inference process can be reduced. this paper, present an improvement method results a reduction statistical analysis. The novel aspect consists use calculate luminosity distance type Ia...
Using the semi-analytic method proposed by \citet{Esma91} we calculate abundances of light elements produced during primordial nucleosynthesis assuming that gauge coupling constants fundamental interactions may vary. We analyze dependence nucleon masses, nuclear binding energies and cross sections involved in calculation with chiral limit QCD. The as a function are obtained. Finally, using observational data $\De$, $\Het$, $\He$ $\Li$ estimate constraints on variation between present. All...
As is well known, measurements of the Sunyaev-Zeldovich effect can be combined with observations X-ray surface brightness galaxy clusters to estimate angular diameter distance these structures. In this paper, we show that technique depends on fine structure constant, α. Therefore, if α a time-dependent quantity, e.g., = α0ϕ(z), where ϕ function redshift, argue current data do not provide real distance, DA(z), cluster, but instead DAdata(z) ϕ(z)2 DA(z). We use result derive constraints...
We propose a new method to probe possible time evolution of the fine structure constant $\alpha$ from X-ray and Sunyaev-Zeldovich measurements gas mass fraction ($f_{gas}$) in galaxy clusters. Taking into account direct relation between variations violations distance-duality relation, we discuss constraints on for class dilaton runaway models. Although not yet competitive with bounds high-$z$ quasar absorption systems, our constraints, considering sample 29 $f_{gas}$, redshift interval $0.14...
A discrete space-time structure lying at about the Planck scale may become manifest in form of very small violations conservation matter energy-momentum tensor. In order to include such kind violations, forbidden within general relativity framework, theory unimodular gravity seems as simplest option describe gravitational interaction. cosmological context, a direct consequence violation energy might be heuristically viewed ``diffusion process (both dark and ordinary)'' into an effective term...
We study the time variation of fundamental constants in early Universe. Using data from primordial light nuclei abundances, cosmic microwave background, and 2dFGRS power spectrum, we put constraints on fine structure constant $\ensuremath{\alpha}$ Higgs vacuum expectation value $⟨v⟩$ without assuming any theoretical framework. A leads to a electron mass, among other effects. Along same line, mass ${m}_{e}$. In purely phenomenological fashion, derive relationship between both variations.
Bolometric interferometry is a novel technique that has the ability to perform spectral imaging. A bolometric interferometer observes sky in wide frequency band and can reconstruct maps several sub-bands within physical post-processing of data. This provides powerful method discriminate between cosmic microwave background (CMB) astrophysical foregrounds. In this paper, methodology illustrated with examples based on Q \& U Interferometer for Cosmology (QUBIC) which ground-based instrument...
We present a comprehensive analysis of statistical tools for evaluating tensions in cosmological parameter estimates arising from distinct datasets. Focusing on the unresolved Hubble constant (H0) tension, we explore Pantheon Plus + SH0ES (PPS) compilation, which includes low-redshift Cepheid data collaboration, along with latest release CMB Planck Cosmic Chronometers (CC) dataset and most recent Baryonic Acoustic Oscillation (BAO) Employing various tension metrics, quantitatively assess...
We update the constraints on time variation of fine structure constant $\alpha$ and electron mass $m_e$, using latest CMB data, including 7-yr release WMAP. made statistical analyses each one constants their joint variation, together with basic set cosmological parameters. used a modified version CAMB COSMOMC to account for these possible variations. present bounds different data sets, show how results depend them. When plus power spectrum from Sloan Digital Sky Survey LRG, we find that...
The hypothesis of the self-induced collapse inflaton wave function was proposed as responsible for emergence inhomogeneity and anisotropy at all scales. This proposal studied within an almost de Sitter space-time approximation background, which led to a perfect scale-invariant power spectrum, also quasi-de allows distinguish departures from standard approach due inclusion hypothesis. In this work we perform Bayesian model comparison two different choices in full expansion scenario....
Recently, active galactic nuclei (AGN) have been proposed as ``standardizable candles,'' thanks to an observed nonlinear relation between their x-ray and optical-ultraviolet (UV) luminosities, which provides independent measurement of distances. In this paper, we use these observables for the first time estimate parameters $f(R)$ gravity models (specifically, Hu-Sawicki exponential models) together with cosmological parameters. The importance types modified theories lies in fact that they...
The field of machine learning has drawn increasing interest from various other fields due to the success its methods at solving a plethora different problems. An application these been train artificial neural networks solve differential equations without need numerical solver. This particular offers an alternative conventional methods, with advantages such as lower memory required store solutions, parallelization, and, in some cases, overall computational cost than counterparts. In this...
We fit the BOOMERANG, MAXIMA and COBE-DMR measurements of cosmic microwave background anisotropy in spatially flat cosmological models where departures from standard recombination primeval plasma are parametrized through a change fine structure constant $\ensuremath{\alpha}$ compared to its present value. In addition we vary baryon dark matter densities, spectral index scalar fluctuations, Hubble constant. Within class considered, lack prominent second acoustic peak measured spectrum can be...
It has been recently claimed that cosmologies with a time dependent speed of light might solve some the problems standard cosmological scenario, as well inflationary scenarios. In this Rapid Communication we show most these models, when analyzed in consistent way, lead to large violations charge conservation. Thus, they are severely constrained by experiment, including those where c is power scale factor and whose source term trace energy-momentum tensor. addition, early universe scenarios...
The possible time variation of the fundamental constants nature has been an active subject research since large-number hypothesis was proposed by Dirac. In this paper, we propose a new method to investigate speed light ($c$) along with fine-structure constant ($\alpha$) using Strong Gravitational Lensing (SGL) and Type Ia Supernovae (SNe Ia) observations. We assume general approach describe mass distribution lens-type galaxies, one in favor power-law index model (PLAW). also consider runaway...
We use the semi-analytic method of Esmailzadeh et al (1991 Astrophys.J. 378 504-18) to calculate abundances helium and deuterium produced during Big Bang nucleosynthesis assuming fine structure constant Higgs vacuum expectation value may vary in time.We analyse dependence on fundamental constants nucleon mass, nuclear binding energies cross sections involved calculation abundances.Unlike previous works, we do not assume chiral limit QCD.Rather, take into account quark masses consider...
Most theories that predict time and/or space variation of fundamental constants also violations the Weak Equivalence Principle. In 2004 Khoury and Weltman proposed so called chameleon field arguing it could help avoiding experimental bounds on WEP while having a non-trivial cosmological impact. this paper we revisit extent to which these expectations continue hold as enter regime high precision tests. The basis study is development new method for computing force between two massive bodies...
The self-induced collapse hypothesis was introduced by D. Sudarsky and collaborators to explain the origin of cosmic structure from a perfect isotropic homogeneous universe during inflationary regime. In this paper, we calculate power spectrum for tensor modes, within semiclassical gravity approximation, with additional generic inflaton's wave function; also compute an estimate tensor-to-scalar ratio. Based on calculation, show that considered proposal exhibits strong suppression modes...
The possibility of variation the fundamental constants nature has been a long-standing question, with important consequences for physics and cosmology. In particular, it shown that variations in fine-structure constant, α, are directly related to violation distance duality relation (DDR), which holds true as long photons travel on unique null geodesics their number is conserved. this paper we use currently available measurements Δ α/α impose most stringent constraints departures DDR date,...