نتایج جستجو برای: cmb model

تعداد نتایج: 2108334  

2013
Anthony Challinor

The cosmic microwave background (CMB) provides us with our most direct observational window to the early universe. Observations of the temperature and polarization anisotropies in the CMB have played a critical role in defining the now-standard cosmological model. In this contribution we review some of the basics of CMB science, highlighting the role of observations made with ground-based and b...

2003
Alejandro Gangui

The common belief that the CMB is Gaussian distributed can be directly traced back to the generic assumption that the quantum fluctuations of the inflaton field are placed in the vacuum state 1. Relaxing this assumption might lead to detectable signatures in various astrophysical tests, most interestingly in future CMB and large-scale structure observations. In this note, we study CMB non-Gauss...

حسین پور, احمد, زارعی, مسلم, قاضی عسگر, سپیده,

The measurement of the polarization of cosmic microwave background (CMB) provides considerable useful information about different physical phenomena at the last scattering surface. The polarization of CMB is due to Compton scattering. In this work, we consider the parity violation of Compton scattering. Then we insert the new amplitude into the quantum Boltzmann equation and show that the forwa...

1998
Charles H. Lineweaver

I present several simple figures to illustrate cosmology and structure formation in a nutshell. Then I discuss the following argument: if we assume that ΩΛ = 0 then the CMB results favor high Ωm while the supernova results favor low Ωm. This large inconsistency is strong evidence for the incorrectness of the ΩΛ = 0 assumption. Finally I discuss recent CMB results on the slope and normalization ...

1999
C. Burigana D. Maino N. Mandolesi F. Villa L. Valenziano M. Bersanelli L. Danese

We simulate Planck observations by adopting a detailed model of the microwave sky including monopole, dipole, anisotropies of the cosmic microwave background (CMB) and galactic and extragalactic foregrounds. We estimate the impact of main beam optical aberrations on CMB anisotropy measurements in presence of extragalactic source fluctuations and we discuss the main implications for the Planck t...

2007
Weijia Kuang Benjamin Fong Chao

A 3-dimensional, fully nonlinear numerical geodynamo model is used to study the core-mantle coupling arising from a non-hydrostatic pressure field acting on an aspherical core-mantle boundary (CMB) based on a seismological model. The simulation results demonstrate that the topographic coupling torque is close to being proportional to the square of the amplitude of the CMB topography. We conclud...

2008
H. K. Eriksen C. Dickinson J. B. Jewell A. J. Banday K. M. Górski C. R. Lawrence

Using a Gibbs sampling algorithm for joint CMB estimation and component separation, we compute the large-scale CMB and foreground posteriors of the 3-yr WMAP temperature data. Our parametric data model includes the cosmological CMB signal and instrumental noise, a single power law foreground component with free amplitude and spectral index for each pixel, a thermal dust template with a single f...

1993
Sergio Torres

Geometric characteristics of random fields are exploited to test the consistency of density perturbation model spectra with COBE data. These CMB maps are analyzed using the number of anisotropy hot spots and their boundary curvature. CMB maps which account for instrumental effects and sky coverage are Monte Carlo generated. These simulations show that a scale invariant HarrisonZeldovich primord...

Journal: :Journal of Cosmology and Astroparticle Physics 2010

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