Vallejo-Peña, Sergio Andrés - Søkeresultater

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The MESS of the CMB / Rodrguez, Manuel Alejandro Jaramillo (ICRA, Pescara ; Antioquia U.) ; Romano, Antonio Enea (ICRA, Pescara ; Antioquia U. ; CERN) ; Vallejo-Peña, Sergio Andrés (ICRA, Pescara ; Antioquia U.)
We analyze cosmic microwave background (CMB) data taking into account the effects of a momentum dependent effective sound speed (MESS). This approach allows to study the effects of primordial entropy in a model independent way, and its implementation requires a minimal modification of existing CMB fitting numerical codes developed for single scalar field models. [...]
arXiv:2006.03395.- 2021-02-17 - 14 p. - Published in : JCAP 2102 (2021) 033 Fulltext: PDF;

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Model-independent approach to effective sound speed in multi-field inflation / Romano, Antonio Enea (CERN ; ICRA, Pescara ; Antioquia U.) ; Vallejo-Peña, Sergio Andrés (ICRA, Pescara ; Antioquia U.) ; Turzyński, Krzysztof (Warsaw U.)
For any physical system satisfying the Einstein's equations, the comoving curvature perturbations satisfy an equation involving the momentum-dependent effective sound speed, valid for any system with a well defined energy-stress tensor, including multi-fields models of inflation. We derive a general model-independent formula for the effective sound speed of comoving adiabatic perturbations, valid for a generic field-space metric, without assuming any approximation to integrate out entropy perturbations, but expressing the momentum-dependent effective sound speed in terms of the components of the total energy-stress tensor. [...]
arXiv:2006.00969.- 2022-08-30 - 16 p. - Published in : Eur. Phys. J. C 82 (2022) 767 Fulltext: Publication - PDF; 2006.00969 - PDF;

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Coordinate independent approach to the calculation of the effects of local structure on the luminosity distance / Vallejo-Peña, Sergio Andrés (ICRA, Pescara ; Antioquia U.) ; Romano, Antonio Enea (CERN ; ICRA, Pescara ; Bishop's U., Sherbrooke ; Antioquia U.)
Local structure can have important effects on luminosity distance observations, which could for example affect the local estimation of the Hubble constant based on low red-shift type Ia supernovae. Using a spherically symmetric exact solution of the Eistein's equations and a more accurate expansion of the solution of the geodesic equations, we improve the low red-shift expansion of the monopole of the luminosity distance in terms of the curvature function. [...]
arXiv:1906.04946.- 2020-03-09 - 18 p. - Published in : JCAP 2003 (2020) 023 Fulltext: PDF;

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The effect of anisotropic stress and non-adiabatic pressure perturbations on the evolution of the comoving curvature perturbation / Naruko, Atsushi (Tohoku U. ; Kyoto U., Yukawa Inst., Kyoto) ; Romano, Antonio Enea (Antioquia U. ; CERN ; Bishop's U., Sherbrooke) ; Sasaki, Misao (Kyoto U., Yukawa Inst., Kyoto ; Tokyo U., IPMU ; Taiwan, Natl. Taiwan U.) ; Vallejo-Peña, Sergio Andrés (Antioquia U.)
We derive the equation for the evolution of the curvature perturbation on the comoving time slice, $\mathcal{R}_c$, in the presence of anisotropic and non-adiabatic terms in the energy-momentum tensor of matter fields. The equation is obtained by manipulating the perturbed Einstein's equations in the comoving time slice. [...]
arXiv:1804.05005; TU-1059; YITP-17-116; IPMU18-0075.- 2019-11-29 - 9 p. - Published in : Class. Quantum Gravity 37 (2020) 017001 Fulltext: PDF;

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Effects of the modification of gravity on the production of primordial black holes / Vallejo-Peña, Sergio Andrés (ICRA, Pescara ; Antioquia U.) ; Romano, Antonio Enea (CERN ; ICRA, Pescara ; Bishop's U., Sherbrooke ; Antioquia U.)
The enhancement of the spectrum of primordial comoving curvature perturbation $\R$ can induce the production of primordial black holes (PBH) which could account for part of present day dark matter. As an example of the effects of the modification of gravity on the production of PBHs, we investigate the effects on the spectrum of $\R$ produced by the modification of gravity in the case of G-inflation, deriving the relation between the unitary gauge curvature perturbation $\zeta$ and the comoving curvature perturbation $\R$, and identifying a background dependent enhancement function $\E$ which can induce large differences between the two gauge invariant variables. [...]
arXiv:1911.03327.- 2021-06-10 - 6 p. - Published in : Phys. Lett. B 817 (2021) 136289 Article from SCOAP3: PDF; Fulltext: PDF; Fulltext from publisher: PDF;

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Are primordial black holes produced by entropy perturbations in single field inflationary models? / Vallejo-Peña, Sergio Andrés (ICRA, Pescara ; Antioquia U.) ; Romano, Antonio Enea (CERN ; ICRA, Pescara ; Antioquia U.)
We show that in single field inflationary models the super-horizon evolution of curvature perturbations on comoving slices $\mathcal{R}$, which can cause the production of primordial black holes (PBH), is not due to entropy perturbations, but to the background evolution effect on the conversion between entropy and curvature perturbations. We derive a general relation between the time derivative of comoving curvature perturbations and entropy perturbations, in terms of a conversion factor depending on the background evolution. [...]
arXiv:1904.07503.- 2019-11-14 - 16 p. - Published in : JCAP 1911 (2019) 015 Fulltext: PDF;

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Se også: lignende forfatternavn
2	Vallejo-Peña, S.A.
1	Vallejo-Peña, Sergio A.

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