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It is well known that the $\Lambda$-term is a very good candidate for the smooth component of the universe since it resolves the so-called ``$\Omega$-problem'' giving, at the same time, sufficiently large age of the universe. However, the…

天体物理学 · 物理学 2009-10-28 Jerzy Stelmach

We reexamine constraints on the spatial size of closed toroidal models with cold dark matter and the cosmological constant from cosmic microwave background. We carry out Bayesian analyses using the Cosmic Background Explorer (COBE) data…

天体物理学 · 物理学 2009-11-07 Kaiki Taro Inoue , Naoshi Sugiyama

We propose a new method for a numerical computation of the angular bispectrum of the CMB anisotropies arising from active models such as cosmic topological defects, using a modified Boltzmann code based on CMBFAST. The method does not use…

天体物理学 · 物理学 2009-11-06 Alejandro Gangui , Levon Pogosian , Serge Winitzki

This is the obligatory Cosmic Microwave Background review. I discuss the current status of CMB anisotropies, together with some points on the related topic of the Far-Infrared Background. We have already learned a number of important things…

天体物理学 · 物理学 2007-05-23 Douglas Scott

We compute maps of CMB temperature fluctuations seeded by cosmic strings using high resolution simulations of cosmic strings in a Friedmann-Robertson-Walker universe. We create full-sky, 18-degree and 3-degree CMB maps, including the…

宇宙学与河外天体物理 · 物理学 2011-02-23 M. Landriau , E. P. S. Shellard

Cosmic microwave background (CMB) anisotropy (spatial inhomogeneity) data provide the tightest constraints on the Hubble constant, matter density, spatial curvature, and dark energy dynamics. Other data, sensitive to the evolution of only…

宇宙学与河外天体物理 · 物理学 2019-09-04 Chan-Gyung Park , Bharat Ratra

The current enthusiam to measure fluctuations in the CMB power spectrum at angular scales between 0.1 and 1 degree is largely motivated by the expectation that CMB determinations of cosmological parameters will be of unprecedented…

天体物理学 · 物理学 2007-05-23 C. H. Lineweaver

We analyse the constraints that can be placed on a cosmological constant or quintessence-like component by combining observations of Type Ia supernovae with measurements of anisotropies in the cosmic microwave background. We use the recent…

天体物理学 · 物理学 2009-10-31 G. Efstathiou

In recent years, upper limits on the cosmic microwave background (CMB) anisotropies combined with predictions made by theories of galaxy formation, have been extremely powerful in ruling out purely baryonic dark matter (BDM) universes.…

天体物理学 · 物理学 2009-11-06 Louise M Griffiths , Alessandro Melchiorri , Joseph Silk

Using the formalism developed in a previous paper we analyze the cosmological implications of our conclusions concerning the scaling behaviour of a network of cosmic strings, in particular the idea that once gravitational back-reaction…

高能物理 - 唯象学 · 物理学 2010-01-06 Daren Austin , E. J. Copeland , T. W. B. Kibble

We investigate the anisotropies of the stochastic gravitational-wave background (SGWB) produced by cosmic strings associated with the spontaneous U(1) symmetry breaking of Grand Unified Theory, which happens at the onset of inflation. The…

宇宙学与河外天体物理 · 物理学 2021-12-21 Rong-Gen Cai , Zong-Kuan Guo , Jing Liu

We explore the large angular scale temperature anisotropies in the cosmic microwave background (CMB) due to homogeneous local dust-filled voids in a flat Friedmann-Robertson-Walker universe with a cosmological constant. In comparison with…

天体物理学 · 物理学 2008-11-26 Kaiki Taro Inoue , Joseph Silk

Using a simple analytic model based on seed superposition we obtain the spectrum of microwave background perturbations induced by cosmic strings on all angular scales larger than about 2 armin. We assume standard recombination in an…

天体物理学 · 物理学 2011-05-10 Leandros Perivolaropoulos

We examine bounds on adiabatic and isocurvature density fluctuations from $\mu$-type spectral distortions of the cosmic microwave background (CMB). Studies of such distortion are complementary to CMB measurements of the spectral index and…

宇宙学与河外天体物理 · 物理学 2013-05-30 James B. Dent , Damien A. Easson , Hiroyuki Tashiro

The number of cosmic strings in the observable universe is relevant in determining the probability of detecting such cosmic defects through their gravitational signatures. In particular, we refer to the observation of gravitational lensing…

宇宙学与河外天体物理 · 物理学 2017-03-15 Rosa Consiglio , Olga Sazhina , Giuseppe Longo , Mikhail Sazhin , Franco Pezzella

We study the effect of weak lensing by cosmic (super-)strings on the anisotropies of cosmic microwave background (CMB). In developing a method to calculate the lensing convergence field due to strings, and thereby temperature and…

宇宙学与河外天体物理 · 物理学 2015-03-19 Daisuke Yamauchi , Keitaro Takahashi , Yuuiti Sendouda , Chul-Moon Yoo

We use analytic calculations of the post-recombination gravitational effects of cosmic strings to estimate the resulting CMB power spectrum, bispectrum and trispectrum. We place a particular emphasis on multipole regimes relevant for…

宇宙学与河外天体物理 · 物理学 2014-11-20 D. M. Regan , E. P. S. Shellard

We investigate cosmological evolution and implications of cosmic strings with time-dependent tension. We derive basic equations of time development of the correlation length and the velocity of such strings, based on the one scale model.…

高能物理 - 唯象学 · 物理学 2008-11-26 Kazuhide Ichikawa , Tomo Takahashi , Masahide Yamaguchi

The emergence of several unexpected large-scale features in the cosmic microwave background (CMB) has pointed to possible new physics driving the origin of density fluctuations in the early Universe and their evolution into the large-scale…

宇宙学与河外天体物理 · 物理学 2018-09-26 Fulvio Melia

We find that current Cosmic Microwave Background (CMB) anisotropy data strongly constrain the mean spatial curvature of the Universe to be near zero, or, equivalently, the total energy density to be near critical-as predicted by inflation.…

天体物理学 · 物理学 2009-10-31 S. Dodelson , L. Knox