Book

Cosmological Clues: Evidence for the Big Bang, Dark Matter and Dark Energy

December 2020

DOI:10.1201/9780367808785

ISBN: 9780367808785

Authors:

A física da radiação cósmica de fundo em micro-ondas

Article

Full-text available

Sep 2023

Luiz Filipe de Oliveira Guimarães

A radiação cósmica de fundo em micro-ondas é um dos principais observáveis da cosmologia desde a sua descoberta. Ela permite a investigação do cosmos desde seus primeiros instantes: do universo primordial, passando pela época de sua formação, e até os dias atuais. Conseguimos extrair de suas propriedades estatísticas traços deixados por todas as épocas do universo. Neste artigo, iremos detalhar como a radiação de fundo foi prevista, detectada, e como sua análise fornece as melhores descrições do universo no passado e no presente.

A New Dark Matter and Dark Energy Theory Based on the Assumption of Mass Vectorization

Article

Jan 2024

FeiFei Zhou

ResearchGate has not been able to resolve any references for this publication.

Article

Massive Structures of Galaxies at High Redshifts in the Great Observatories Origins Deep Survey Fiel...

February 2015 · Journal of The Korean Astronomical Society

If the Universe is dominated by cold dark matter and dark energy as in the currently popular ΛCDM cosmology, it is expected that large scale structures form gradually, with galaxy clusters of mass M ≥ 1014M⊙ appearing at around 6. Gyrs after the Big Bang (z ~ 1). Here, we report the discovery of 59 massive structures of galaxies with masses greater than a few times 1013M⊙ at redshifts between z = ... [Show full abstract] 0.6 and 4.5 in the Great Observatories Origins Deep Survey fields. The massive structures are identified by running top-hat filters on the two dimensional spatial distribution of magnitude-limited samples of galaxies using a combination of spectroscopic and photometric redshifts. We analyze the Millennium simulation data in a similar way to the analysis of the observational data in order to test the ΛCDM cosmology. We find that there are too many massive structures (M > 7×1013M⊙) observed at z > 2 in comparison with the simulation predictions by a factor of a few, giving a probability of < 1/2500 of the observed data being consistent with the simulation. Our result suggests that massive structures have emerged early, but the reason for the discrepancy with the simulation is unclear. It could be due to the limitation of the simulation such as the lack of key, unrecognized ingredients (strong non-Gaussianity or other baryonic physics), or simply a difficulty in the halo mass estimation from observation, or a fundamental problem of the ΛCDM cosmology. On the other hand, the over-abundance of massive structures at high redshifts does not favor heavy neutrino mass of ~ 0.3 eV or larger, as heavy neutrinos make the discrepancy between the observation and the simulation more pronounced by a factor of 3 or more.

Article

Full-text available

Big bang nucleosynthesis and CMB constraints on dark energy

March 2003 · Physical Review D

Current observational data favor cosmological models which differ from the standard model due to the presence of some form of dark energy and, perhaps, by additional contributions to the more familiar dark matter. Primordial nucleosynthesis provides a window on the very early evolution of the universe and constraints from big bang nucleosynthesis (BBN) can bound the parameters of models for dark ... [Show full abstract] matter or energy at redshifts of the order of ten billion. The spectrum of temperature fluctuations imprinted on the cosmic microwave background (CMB) radiation opens a completely different window on the universe at epochs from redshifts of the order of ten thousand to nearly the present. The CMB anisotropy spectrum provides constraints on new physics which are independent of and complementary to those from BBN. Here we consider three classes of models for the dark matter or energy: extra particles which were relativistic during the early evolution of the universe (“X”); quintessence models involving a minimally coupled scalar field (“Q”); models with a non-minimally coupled scalar field which modify the strength of gravity during the early evolution of the universe (“G”). We constrain the parameters of these models using data from BBN and the CMB and identify the allowed regions in their parameter spaces consistent with the more demanding joint BBN and CMB constraints. For “X” and “Q” such consistency is relatively easy to find; it is more difficult for the “G” models with an inverse power law potential for the scalar field.

Article

Full-text available

Planck 2015 results. XIII. Cosmological parameters

February 2015 · Astronomy and Astrophysics

We present results based on full-mission Planck observations of temperature and polarization anisotropies of the CMB. These data are consistent with the six-parameter inflationary LCDM cosmology. From the Planck temperature and lensing data, for this cosmology we find a Hubble constant, H0= (67.8 +/- 0.9) km/s/Mpc, a matter density parameter Omega_m = 0.308 +/- 0.012 and a scalar spectral index ... [Show full abstract] with n_s = 0.968 +/- 0.006. (We quote 68% errors on measured parameters and 95% limits on other parameters.) Combined with Planck temperature and lensing data, Planck LFI polarization measurements lead to a reionization optical depth of tau = 0.066 +/- 0.016. Combining Planck with other astrophysical data we find N_ eff = 3.15 +/- 0.23 for the effective number of relativistic degrees of freedom and the sum of neutrino masses is constrained to < 0.23 eV. Spatial curvature is found to be |Omega_K| < 0.005. For LCDM we find a limit on the tensor-to-scalar ratio of r <0.11 consistent with the B-mode constraints from an analysis of BICEP2, Keck Array, and Planck (BKP) data. Adding the BKP data leads to a tighter constraint of r < 0.09. We find no evidence for isocurvature perturbations or cosmic defects. The equation of state of dark energy is constrained to w = -1.006 +/- 0.045. Standard big bang nucleosynthesis predictions for the Planck LCDM cosmology are in excellent agreement with observations. We investigate annihilating dark matter and deviations from standard recombination, finding no evidence for new physics. The Planck results for base LCDM are in agreement with BAO data and with the JLA SNe sample. However the amplitude of the fluctuations is found to be higher than inferred from rich cluster counts and weak gravitational lensing. Apart from these tensions, the base LCDM cosmology provides an excellent description of the Planck CMB observations and many other astrophysical data sets.

Article

Full-text available

Physical Alternative to the Dark Energy Paradigm

February 2017 · Open Astronomy

A. Sapar

The physical nature of the presently dominating enigmatic dark energy in the expanding universe is demonstrated to be explainable as an excess of the kinetic energy with respect to its potential energy. According to traditional Friedman cosmology, any non-zero value of the total energy integral is ascribed to the space curvature. However, as we show, in the flat universe the total energy also can ... [Show full abstract] be different from zero. Initially, a very small excess of kinetic energy originates from the early universe. The present observational data show that our universe has probably a flat space with an excess of kinetic energy. The evolutionary scenario shows that the universe presently is in the transitional stage where its radial coordinate expansion approaches the velocity of light. A possibility of the closed Bubble universe with the local Big Bang and everlasting expansion is demonstrated. Dark matter can be essentially contributed by the non-relativistic massive neutrinos, which have cooled to very low temperatures and velocities thus favoring the formation of the observed broad equipotential wells in galaxies.

Article

Cosmology of fermionic dark matter

August 2007 · Physical Review D

We explore a model for a fermionic dark matter particle family which decouples from the rest of the partices when at least all standard model particles are in equilibrium. We calculate the allowed ranges for mass and chemical potential to be compatible with big bang nucleosynthesis (BBN) calculations and WMAP-data for a flat universe with dark energy. Futhermore we estimate the free streaming ... [Show full abstract] length for fermions and antifermions to allow comparison to large scale structure data (LLS). We find that for dark matter decoupling when all standard model particles are present even the least restrictive combined BBN calculation and WMAP results allow us to constrain the initial dark matter chemical potential to a highest value of 6.3 times the dark matter temperature. In this case the resulting mass range is at most 1.8 eV < m < 53 eV, where the upper bound scales linearly with the effective degrees of freedom at decoupling. From LSS we find that similar to ordinary warm dark matter models the particle mass has to be larger than approximately 500 eV (meaning the effective degrees of freedom at decoupling have to be > 1000) to be compatible with observations of the Ly alpha forest at high redshift, but still the dark matter chemical potential over temperature ratio can exceed unity.

Article

Modern Cosmology

March 2003 · Physics Today

Scott Dodelson

Modern Cosmology begins with an introduction to the smooth, homogeneous universe described by a Friedmann-Robertson-Walker metric, including careful treatments of dark energy, big bang nucleosynthesis, recombination, and dark matter. From this starting point, the reader is introduced to perturbations about an FRW universe: their evolution with the Einstein-Boltzmann equations, their generation by ... [Show full abstract] primordial inflation, and their observational consequences. These consequences include the anisotropy spectrum of the cosmic microwave background (CMB) featuring acoustic peaks and polarization, the matter power spectrum with baryonic wiggles, and their detection via photometric galaxy surveys, redshift distortions, cluster abundances, and Modern Cosmology is the first book to explain in detail the structure of the acoustic peaks in the CMB, the E/B decomposition in polarization which may allow for detection of primordial gravity waves, and the modern analysis techniques used on increasingly large cosmological data sets. Readers will gain the tools needed to work in cosmology and learn how modern observations are rapidly revolutionizing our picture of the universe.

Article

Full-text available

Modified holographic Ricci dark energy coupled to interacting dark matter and a non interacting bary...

January 2013 · The European Physical Journal C

We examine a Friedmann–Robertson–Walker universe filled with interacting dark matter, modified holographic Ricci dark energy (MHRDE), and a decoupled baryonic component. The estimations of the cosmic parameters with Hubble data lead to an age of the universe of 13.17 Gyr and show that the MHRDE is free from the cosmic-age problem at low redshift (0≤z≤2) in contrast to holographic Ricci dark ... [Show full abstract] energy (HRDE) case. We constrain the parameters with the Union2 data set and contrast with the Hubble data. We also study the behavior of dark energy at early times by taking into account the severe bounds found at recombination era and/or at big bang nucleosynthesis. The inclusion of a non-interacting baryonic matter forces that the amount of dark energy at

z_{t} \sim\mathcal{O}(1)

changes abruptly implying that Ω x (z≃1100)=0.03, so the bounds reported by the forecast of Planck and CMBPol experiments are more favored for the MHRDE model than in the case of HRDE cutoff. For the former model, we also find that at high redshift the fraction of dark energy varies from 0.006 to 0.002, then the amount of Ω x at the big bang nucleosynthesis era does not disturb the observed helium abundance in the universe provided that the bound Ω x (z≃1010)<0.21 is hold.

Article

Full-text available

A origem do universo

December 2006 · Estudos Avançados

J. E. Steiner

The various cosmological models along history are briefly reviewed. The evolution of the ideas may be understood as successive models such as the flat earth, the geocentric models as well as the heliocentric and the galacto-centric ones. In the last century, a concept was developed, the big-bang theory, that describes the most sophisticated observations on hand today and shows that the universe ... [Show full abstract] had an origin that can be search with scientific methods. In recent decades this model was refined to a new concept: inflation. By the end of the century and millenium new discoveries showed that all known matter is only the tip of the iceberg in a universe dominated by dark energy and dark matter whose natures remain mysterious.

Article

The Cosmic Microwave Background Radiation - A Unique Window on the Early Universe

January 2009

G. Hinshaw

The cosmic microwave background radiation is the remnant heat from the Big Bang. It provides us with a unique probe of conditions in the early universe, long before any organized structures had yet formed. The anisotropy in the radiation's brightness yields important clues about primordial structure and additionally provides a wealth of information about the physics of the early universe. Within ... [Show full abstract] the framework of inflationary dark matter models, observations of the anisotropy on sub-degree angular scales reveals the signatures of acoustic oscillations of the photon-baryon fluid at a redshift of 1100. Data from the Wilkinson Microwave Anisotropy Probe (WMAP) satellite provide detailed full-sky maps of the cosmic microwave background temperature and polarization anisotropy. Together, the data provide a wealth of cosmological information, including the age of the universe, the epoch when the first stars formed, and the overall composition of baryonic matter, dark matter, and dark energy. The results also provide constraints on the period of inflationary expansion in the very first moments of time.

Article

Recent progress in simulating galaxy formation from the largest to the smallest scales

April 2018 · Nature Astronomy

Claude-André Faucher-Giguère

Galaxy formation simulations are an essential part of the modern toolkit of astrophysicists and cosmologists alike. Astrophysicists use the simulations to study the emergence of galaxy populations from the Big Bang, as well as the formation of stars and supermassive black holes. For cosmologists, galaxy formation simulations are needed to understand how baryonic processes affect measurements of ... [Show full abstract] dark matter and dark energy. Owing to the extreme dynamic range of galaxy formation, advances are driven by novel approaches using simulations with different tradeoffs between volume and resolution. Large-volume but low-resolution simulations provide the best statistics, while higher-resolution simulations of smaller cosmic volumes can be evolved with self-consistent physics and reveal important emergent phenomena. I summarize recent progress in galaxy formation simulations, including major developments in the past five years, and highlight some key areas likely to drive further advances over the next decade. Due to the extreme dynamic range, galaxy formation simulations rely on different tradeoffs between volume and resolution. Recent progress is summarized and some key areas likely to drive further advances over the next decade are highlighted.

Article

The cosmic web and microwave background fossilize the first turbulent combustion

June 2014 · Proceedings of the International Astronomical Union

Collisional fluid mechanics theory predicts a turbulent hot big bang at Planck conditions from large, negative, turbulence stresses below the Fortov-Kerr limit (< −10 ¹¹³Pa ). Big bang turbulence fossilized when quarks formed, extracting the mass energy of the universe by extreme negative viscous stresses of inflation, expanding to length scales larger than the horizon scale ct. ... [Show full abstract] Viscous-gravitational structure formation by fragmentation was triggered at big bang fossil vorticity turbulence vortex lines during the plasma epoch, as observed by the Planck space telescope. A cosmic web of protogalaxies, protogalaxyclusters, and protogalaxysuperclusters that formed in turbulent boundary layers of the spinning voids are hereby identified as expanding turbulence fossils that falsify CDMHC cosmology.

Article

Full-text available

A Cosmological Model without Singularity and Dark Matter

January 2010

Shi-Hao Chen

According to the cosmological model without singularity, there are s-matter and v-matter which are symmetric and have oppose gravitational masses. In V-breaking s-matter is similar to dark energy to cause expansion of the universe with an acceleration now, and v-matter is composed of v-F-matter and v-W-matter which are symmetric and have the same gravitational masses and forms the world. The ... [Show full abstract] ratio of s-matter to v-matter is changeable. Based on the cosmological model, we confirm that big bang nucleosynthesis is not spoiled by that the average energy density of W-matter (mirror matter) is equal to that of F-matter (ordinary matter). According to the present model, there are three sorts of dark matter which are v-W-baryon matter (4/27), unknown v-F-matter (9.5/27) and v-W-matter (9.5/27). Given v-F-baryon matter (4/27) and v-W-baryon matter can cluster and respectively form the visible galaxies and dark galaxies. Unknown v-F-matter and v-W-matter cannot cluster to form any celestial body, loosely distribute in space, are equivalent to cold dark matter, and their compositions are unknown. The number in a bracket is the ratio of the density of a sort of matter to total density of v-matter. The decisive predict is that there are dark celestial bodies and dark galaxies. The energy of F-matter can transform into the energy of W-matter by such a process in which the reaction energy is high enough. Comment: 10 pages, 3 figures