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Among the suggested solutions to the cosmological constant problem, we find the idea of a dynamic vacuum, with an energy density decaying with the universe expansion. We investigate the possibility of a variation in the gravitational…

General Relativity and Quantum Cosmology · Physics 2011-08-17 Saulo Carneiro

Standard cosmology predicts that prior to matter-radiation equality about 41% of the energy density was in free-streaming neutrinos. In many beyond Standard Model scenarios, however, the amount and free-streaming nature of this component is…

Cosmology and Nongalactic Astrophysics · Physics 2020-09-30 Nikita Blinov , Gustavo Marques-Tavares

We highlight recent progress in the sophistication and diversification of cosmic dawn and reionization simulations. The application of these modeling tools to current observations has allowed us narrow down the timing of reionization, which…

Cosmology and Nongalactic Astrophysics · Physics 2018-08-22 Andrei Mesinger

The physical ingredients to describe the epoch of cosmological recombination are amazingly simple and well-understood. This fact allows us to take into account a very large variety of processes, still finding potentially measurable…

Astrophysics · Physics 2008-02-06 R. A. Sunyaev , J. Chluba

We study the constraints which the next generation of radio telescopes could place on the nature of dark energy, dark matter and inflation by studying the gravitational lensing of high redshift 21 cm emission, and we compare with the…

Astrophysics · Physics 2009-06-23 R. Benton Metcalf , S. D. M. White

In the standard cosmological model the dark energy (DE) and nonrelativistic (NR) matter densities are observationally determined to be comparable at the present time, in spite of their greatly different evolution histories. This `cosmic…

Cosmology and Nongalactic Astrophysics · Physics 2022-08-30 Meir Shimon

We explore a model in which the cosmological constant $\Lambda$ and the density contrast at the time of recombination $\sigma_{rec}$ are random variables, whose range and {\it a priori} probabilities are determined by the laws of physics.…

Astrophysics · Physics 2016-08-25 Jaume Garriga , Mario Livio , Alexander Vilenkin

The standard cosmological model is sufficiently well constrained that precise estimates can be provided for the redshift of various physically defined times in the chronology of the Universe. For example, it is well known that…

Cosmology and Nongalactic Astrophysics · Physics 2024-11-13 Lukas Tobias Hergt , Douglas Scott

The density contrast of the Universe, parametrized in terms of the matter power spectrum and its variance, can amplify the signal of the free-free process in the plasma. The damping of fluctuations on scales smaller than the DM particle…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 Tiziana Trombetti , Carlo Burigana

This conference proceedings paper provides a short summary of the constraints presented in Menci et al. 2016, 2017 on the mass of thermal WDM candidates, and of the results presented in Romanello et al. 2021 on how Reionization scenarios…

Cosmology and Nongalactic Astrophysics · Physics 2023-01-11 Marco Castellano , Nicola Menci , Massimiliano Romanello

The interacting and holographic dark energy models involve two important quantities. One is the characteristic size of the holographic bound and the other is the coupling term of the interaction between dark energy and dark matter. Rather…

High Energy Physics - Theory · Physics 2008-11-26 Bo Hu , Yi Ling

We review the observable consequences of the epoch of reionization (EoR) on the cosmic microwave background (CMB), and the resulting constraints on the EoR. We discuss how Thomson scattering with the free electrons produced during EoR…

Cosmology and Nongalactic Astrophysics · Physics 2016-01-27 Christian L. Reichardt

An ionization front expanding into a neutral medium can be slowed-down significantly by recombinations. In cosmological numerical simulations the recombination rate is often computed using a 'clumping factor', that takes into account that…

Cosmology and Nongalactic Astrophysics · Physics 2016-08-17 Milan Raičević , Tom Theuns

The measurements of the 21-cm brightness temperature fluctuations from the neutral hydrogen at the Epoch of Reionization (EoR) should inaugurate the next generation of cosmological observables. In this respect, many works have concentrated…

Cosmology and Nongalactic Astrophysics · Physics 2013-01-10 Sebastien Clesse , Laura Lopez-Honorez , Christophe Ringeval , Hiroyuki Tashiro , Michel H. G. Tytgat

We study unimodular gravity in the context of cosmology, particularly some interesting consequences that might be able to describe the background cosmology and the late cosmic acceleration. We focus our attention on the hypothesis of…

General Relativity and Quantum Cosmology · Physics 2019-06-26 Miguel A. García-Aspeitia , C. Martínez-Robles , A. Hernández-Almada , Juan Magaña , V. Motta

Non-parametric reconstruction or marginalization over the history of reionization using cosmic microwave background data necessarily assumes a prior over possible histories. We show that different but reasonable choices of priors can shift…

Cosmology and Nongalactic Astrophysics · Physics 2018-10-03 Marius Millea , François Bouchet

During cosmic reionization, the 21-cm brightness fluctuations were highly non-Gaussian, and complementary statistics can be extracted from the distribution of pixel brightness temperatures that are not derivable from the 21-cm power…

Cosmology and Nongalactic Astrophysics · Physics 2012-09-27 Tony Pan , Rennan Barkana

The epoch of reionisation is a key phase in cosmic history, characterised by the ionisation of the intergalactic medium by the first luminous sources. In this work, we constrain the reionisation history of the Universe using data from the…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-18 S. Ilić , M. Tristram , M. Douspis , A. Gorce , S. Henrot-Versillé , L. T. Hergt , M. Langer , L. McBride , M. Muñoz-Echeverría , E. Pointecouteau , L. Salvati

In this paper we show how the rescattering of CMB photons after cosmic reionization can give a significant linear contribution to the temperature-matter cross-correlation measurements. These anisotropies, which arise via a late time Doppler…

Astrophysics · Physics 2008-11-26 Tommaso Giannantonio , Robert Crittenden

We use a compilation of cosmic microwave anisotropy data to constrain the epoch of reionization in the Universe, as a function of cosmological parameters. We consider spatially-flat cosmologies, varying the matter density $\Omega_0$ (the…

Astrophysics · Physics 2009-10-31 Louise M Griffiths , Domingos Barbosa , Andrew R Liddle