A5087343666- Cosmology and Gravitation Theories
- Galaxies: Formation, Evolution, Phenomena
- Black Holes and Theoretical Physics
- Geophysics and Gravity Measurements
- Pulsars and Gravitational Waves Research
- Gamma-ray bursts and supernovae
- Relativity and Gravitational Theory
- Radio Astronomy Observations and Technology
- Solar and Space Plasma Dynamics
- Astronomy and Astrophysical Research
- Advanced Differential Geometry Research
- High-pressure geophysics and materials
- Scientific Research and Discoveries
- Dark Matter and Cosmic Phenomena
- Computational Physics and Python Applications
- Astrophysics and Cosmic Phenomena
- Geophysics and Sensor Technology
- Neural dynamics and brain function
- Advanced Thermodynamics and Statistical Mechanics
- Statistical and numerical algorithms
- stochastic dynamics and bifurcation
- Optical and Acousto-Optic Technologies
- Biofield Effects and Biophysics
- Inertial Sensor and Navigation
- Renaissance Literature and Culture
Universidad de Antioquia
2015-2024
International Center for Relativistic Astrophysics
2017-2024
Kyoto University
2011-2024
European Organization for Nuclear Research
2017-2023
Bishop's University
2019-2021
King's College London
2018
University of Crete
2014-2017
National Taiwan University
2010-2014
McGill University
2014
Perimeter Institute
2012
Abstract We outline the “dark siren” galaxy catalog method for cosmological inference using gravitational wave (GW) standard sirens, clarifying some common misconceptions in implementation of this method. When a confident transient electromagnetic counterpart to GW event is unavailable, identification unique host general challenging. Instead, as originally proposed by Schutz, one can consult and implement dark siren statistical approach incorporating all potential galaxies within...
Abstract In the absence of numerous gravitational-wave detections with confirmed electromagnetic counterparts, “dark siren” method has emerged as a leading technique cosmology. The allows redshift information such events to be inferred statistically from catalogue potential host galaxies. Due selection effects, dark siren analyses necessarily depend on mass distribution compact objects and evolution their merger rate redshift. Informative priors these quantities will impact posterior...
We derive an effective equation and action for the propagation of gravitational waves (GW), encoding effects interaction self-interaction in a time, frequency polarization dependent speed. In terms appropriately defined metric, takes form massless Klein-Gordon action. This approach predicts that theories with matter coupled to Einstein frame metric ratio between electromagnetic (EM) luminosity distance depends on speed, while Jordan coupling it Planck mass. discuss how dependence GW-EM...
We derive a direct general map from the luminosity distance ${D}_{L}(z)$ to inhomogeneous matter distribution $M(r)$ in Lemaitre-Tolman-Bondi (LTB) cosmology and compute several examples. One of our examples explicitly demonstrates that it is possible tune LTB cosmological solution approximately reproduce curve flat Friedmann-Robertson-Walker universe with constant. also discuss how smooth distributions can evolve into naked singularities due shell crossing when ``curvature'' $E(r)$ function...
The impact of particle production during inflation on the primordial curvature perturbation spectrum is investigated both analytically and numerically. We obtain an oscillatory behavior small scales, while large scales unaffected. amplitude oscillations proportional to number coupled fields, their mass, square coupling constant. are due a discontinuity in second time derivative inflaton, arising from temporary violation slow-roll conditions. A similar effect power should be produced also...
We study an inflationary model driven by a single minimally coupled standard kinetic term scalar field with step in its mass modeled Heaviside function. present analytical approximation for the mode function of curvature perturbation, obtain power spectrum analytically and compare it numerical result. show that, after scale set step, contains damped oscillations that are well described our approximation. also compute dominant contribution to bispectrum equilateral squeezed limits find new...
A step-by-step approach is followed to study cosmic structures in the context of Brans-Dicke theory with positive cosmological constant Λ and parameter ω. First, it shown that regular stationary black-hole solutions not only have field ϕ, but can exist for ω=∞, which forces coincide general relativity. Generalizations order evade this no-hair theorem are presented. It also absence a event horizon asymptotic region, support nontrivial hair. Even more importantly, next presence rules out any...
Using conformal invariance of gravitational waves, we show that for a luminal modified gravity theory, the gravitational-wave propagation and luminosity distance are same as in general relativity. The relation between electromagnetic-wave gets modified, however, electromagnetism minimally coupled to Jordan frame metric. effective field theory obtained theories is also valid nonluminal with matter-gravity coupling. We generalize our analysis time-dependent speed waves matter either or...
The recent analysis of low-redshift supernovae (SN) has increased the apparent tension between value $H_0$ estimated from low and high redshift observations such as cosmic microwave background (CMB) radiation. At same time other have provided evidence existence local radial inhomogeneities extending in different directions up to a about $0.07$. About $40\%$ Cepheids used for SN calibration are directly affected because located along these inhomogeneities. We derive new simple formula...
Supernovae observations strongly support the presence of a cosmological constant, but its value, which we will call apparent, is normally determined assuming that Universe can be accurately described by homogeneous model. Even in constant cannot exclude nevertheless small local inhomogeneity could affect apparent value constant. Neglecting fact introduce systematic misinterpretation data, leading to distinction between an and true We establish theoretical framework calculate corrections...
We study the effects of a class features inflaton potential, corresponding to discontinuities in its derivatives. perform fully numerical calculations and derive analytical approximations for curvature perturbations spectrum bispectrum which are good agreement with results. The primordial has oscillations around scale $$k_0$$ leaves horizon at time $$\tau _0$$ when feature occurs, amplitude phase determined by size order discontinuity. large squeezed equilateral limits have very similar form...
The maximum size of a cosmic structure is given by the turnaround radius -- scale where attraction due to its mass balanced repulsion dark energy. We derive generic formulae for estimation in any theory gravity obeying Einstein equivalence principle, two situations: on spherically symmetric spacetime and perturbed Friedman-Robertson-Walker spacetime. show that agree. As an application our formula, we calculate case Brans-Dicke gravity. find this theory, such sizes always lie above \LCDM...
In the context of single-field inflation, conservation curvature perturbation on comoving slices, $\R_c$, super-horizon scales is one assumptions necessary to derive consistency condition between squeezed limit bispectrum and spectrum primordial perturbation. However, $\R_c$ holds only after has reached adiabatic where constant mode dominates over other (usually decaying) mode. this case, non-adiabatic pressure defined in thermodynamic sense, $\delta P_{nad}\equiv\delta P-c_w^2\delta\rho$...
We show that positive averaged acceleration ${a}_{D}$ obtained in Lemaitre-Tolman-Bondi (LTB) models through spatial averaging can require integration over a region beyond the event horizon of central observer. provide an example LTB model with which luminosity distance ${D}_{L}(z)$ does not contain information about entire spatially region, making unobservable. Since cosmic ${a}^{\mathrm{FRW}}$ is from fitting observed to Friedmann-Robertson-Walker (FRW) we conclude general imply...
We carefully study the implications of adiabaticity for behavior cosmological perturbations. There are essentially three similar but different definitions non-adiabaticity: one is appropriate a thermodynamic fluid δPnad, another general matter field δPc,nad, and last valid only on superhorizon scales. The first two coincide if cs2=cw2 where cs propagation speed perturbation, while cw2=P˙/ρ˙. Assuming in sense, δPc,nad=0, we derive relation between lapse function comoving slicing Ac δPnad...
Assuming the definition of inversion problem (IP) as exact matching terms in low redshift expansion cosmological observables calculated for different models, we solve IP ${D}_{L}(z)$ and spherical shell mass density $mn(z)$ a central observer Lemaitre-Tolman-Bondi (LTB) space without constant generic $\ensuremath{\Lambda}\mathrm{CDM}$ model. We show that solution is unique, corresponds to matter profile which not smooth at center, same conclusions can be reached expanding self-consistently...
As an alternative to dark energy it has been suggested that we may be at the center of inhomogeneous isotropic universe described by a Lemaitre-Tolman-Bondi (LTB) solution Einstein's field equations. In order test such hypothesis calculate low redshift expansion luminosity distance DL(z) and spherical shell mass density mn(z) for central observer in LTB space without cosmological constant show how they cannot fit observations implied ΛCDM model if conditions avoid weak singularity are...
We study the effects of a class features potential slow-roll inflationary models corresponding to step symmetrically dumped by an even power negative exponential factor, which we call local features. Local-type differ from other branch-type considered previously, because is only affected in limited range scalar field value, and they are symmetric with respect location feature. This type feature affects spectrum bispectrum narrow scales leave horizon during time interval modification...
We introduce the redshift spherical shell energy, which can be used to test in space radial inhomogeneity of an isotropic universe, providing additional constraints for Lemaitre-Tolman-Bondi models, and a more general cosmic homogeneity.
We present a general analytical formalism to calculate accurately several statistics related underdense regions in the Universe. The are computed for dark matter halo and galaxy distributions both real space redshift at any redshift. Using this formalism, we found that void can be obtained, very good approximation, assuming galaxies have same clustering properties as halos above certain mass. deducted relationship between mass of with accumulated number density galaxies. also dependence on...
As an alternative to dark energy it has been suggested that we may be at the center of inhomogeneous isotropic universe described by a Lemaitre-Tolman-Bondi (LTB) solution Einstein's field equations. In order test this hypothesis calculate general analytical formula fifth for redshift spherical shell mass. Using same method write metric in light-cone introducing gauge invariant quantity $G(z)$ which together with luminosity distance $D_L(z)$ completely determine geometry LTB model.
Recent measurements of the cosmic microwave background (CMB) radiation have shown an apparent tension with present value Hubble parameter inferred from local observations supernovae, which look closer, i.e. brighter, than what is expected in a homogeneous model H0 equal to one estimated CMB observations.We examine possibility that such discrepancy consequence presence inhomogeneity seeded by primordial curvature perturbations, finding negative peak order less two standard deviations could...
Abstract There is a strong discrepancy between the value of Hubble parameter $$H_0^P$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>H</mml:mi> <mml:mn>0</mml:mn> <mml:mi>P</mml:mi> </mml:msubsup> </mml:math> obtained from large scale observations such as Planck mission, and small $$H_0^R$$ <mml:mi>R</mml:mi> , low redshift supernovae (SNe). The absolute magnitude $$M^{Hom}$$ <mml:msup> <mml:mi>M</mml:mi> <mml:mrow> <mml:mi>Hom</mml:mi> </mml:mrow>...