scholarly journals STRONG LENSING PROBABILITIES IN A COSMOLOGICAL MODEL WITH A RUNNING PRIMORDIAL POWER SPECTRUM

2005 ◽  
Vol 20 (11) ◽  
pp. 851-859 ◽  
Author(s):  
TONG-JIE ZHANG ◽  
ZHI-LIANG YANG ◽  
XIANG-TAO HE
Keyword(s):  
Power Spectrum ◽  
Cosmological Model ◽  
Spectral Power ◽  
Density Fluctuations ◽  
Wilkinson Microwave Anisotropy Probe ◽  
First Year ◽  
Microwave Background ◽  
Primordial Power Spectrum ◽  
Λcdm Model ◽  
Image Separation

The combination of the first-year Wilkinson Microwave Anisotropy Probe (WMAP) data with other finer scale cosmic microwave background (CMB) experiments (CBI and ACBAR) and two structure formation measurements (2dFGRS and Lyman α forest) suggest a ΛCDM cosmological model with a running spectral power index of primordial density fluctuations. Motivated by this new result on the index of primordial power spectrum, we present the first study on the predicted lensing probabilities of image separation in a spatially flat ΛCDM model with a running spectral index (RSI-ΛCDM model). It is shown that the RSI-ΛCDM model suppresses the predicted lensing probabilities on small splitting angles of less than about 4″ compared with that of standard power-law ΛCDM (PL-ΛCDM) model.

scholarly journals Reconstructing the Primordial Power Spectrum

2005 ◽  
Vol 216 ◽  
pp. 28-34
Author(s):  
S. L. Bridle ◽  
A. M. Lewis ◽  
J. Weller ◽  
G. Efstathiou
Keyword(s):  
Power Spectrum ◽  
Spectral Index ◽  
Large Scale ◽  
Cosmological Parameters ◽  
Wilkinson Microwave Anisotropy Probe ◽  
Microwave Background ◽  
Primordial Power Spectrum ◽  
Initial Spectrum ◽  
Redshift Survey ◽  
Cosmic Microwave Background Data

We reconstruct the shape of the primordial power spectrum from the latest cosmic microwave background data, including the new results from the Wilkinson Microwave Anisotropy Probe (WMAP), and large scale structure data from the two degree field galaxy redshift survey (2dFGRS). We discuss two parameterizations taking into account the uncertainties in four cosmological parameters. First we parameterize the initial spectrum by a tilt and a running spectral index, finding marginal evidence for a running spectral index only if the first three WMAP multipoles (ℓ = 2, 3, 4) are included in the analysis. Secondly, to investigate further the low CMB large scale power, we modify the conventional power-law spectrum by introducing a scale above which there is no power. We find a preferred position of the cut at kc ∼ 3 × 10--4 Mpc--1 although kc = 0 (no cut) is not ruled out.

scholarly journals EARLY UNIVERSE SOURCES FOR CMB NON-GAUSSIANITY

2002 ◽  
Vol 17 (29) ◽  
pp. 4273-4280
Author(s):  
ALEJANDRO GANGUI
Keyword(s):  
Power Spectrum ◽  
Cosmic Microwave Background ◽  
Early Universe ◽  
Microwave Background ◽  
Scale Invariant ◽  
Invariant Model ◽  
Primordial Power Spectrum ◽  
Initial States ◽  
Non Gaussian ◽  
Inflationary Models

In the framework of inflationary models with non-vacuum initial states for cosmological perturbations, we study non-Gaussian signatures on the cosmic microwave background (CMB) radiation produced by a broken-scale-invariant model which incorporates a feature at a privileged scale in the primordial power spectrum.

scholarly journals Connecting the structure of dark matter haloes to the primordial power spectrum

2020 ◽  
Vol 495 (4) ◽  
pp. 4994-5013 ◽  
Author(s):  
Shaun T Brown ◽  
Ian G McCarthy ◽  
Benedikt Diemer ◽  
Andreea S Font ◽  
Sam G Stafford ◽  
...  
Keyword(s):  
Dark Matter ◽  
Power Spectrum ◽  
Cold Dark Matter ◽  
Initial Conditions ◽  
Mass Density ◽  
Large Body ◽  
Density Fluctuations ◽  
Physical Models ◽  
Halo Structure ◽  
Primordial Power Spectrum

ABSTRACT A large body of work based on collisionless cosmological N-body simulations going back over two decades has advanced the idea that collapsed dark matter (DM) haloes have simple and approximately universal forms for their mass density and pseudo-phase-space density (PPSD) distributions. However, a general consensus on the physical origin of these results has not yet been reached. In the present study, we explore to what extent the apparent universality of these forms holds when we vary the initial conditions (i.e. the primordial power spectrum of density fluctuations) away from the standard CMB-normalized case, but still within the context of lambda cold dark matter with a fixed expansion history. Using simulations that vary the initial amplitude and shape, we show that the structure of DM haloes retains a clear memory of the initial conditions. Specifically, increasing (lowering) the amplitude of fluctuations increases (decreases) the concentration of haloes and, if pushed far enough, the density profiles deviate strongly from the NFW form that is a good approximation for the CMB-normalized case. Although, an Einasto form works well. Rather than being universal, the slope of the PPSD (or pseudo-entropy) profile steepens (flattens) with increasing (decreasing) power spectrum amplitude and can exhibit a strong halo mass dependence. Our results therefore indicate that the previously identified universality of the structure of DM haloes is mostly a consequence of adopting a narrow range of (CMB-normalized) initial conditions for the simulations. Our new suite provides a useful test-bench against which physical models for the origin of halo structure can be validated.

f(R) COSMOLOGY AND MASSIVE NEUTRINOS

2012 ◽  
Vol 10 ◽  
pp. 35-42 ◽  
Author(s):  
HAYATO MOTOHASHI ◽  
ALEXEI A. STAROBINSKY ◽  
JUN'ICHI YOKOYAMA
Keyword(s):  
Equation Of State ◽  
Power Spectrum ◽  
State Parameter ◽  
Density Fluctuations ◽  
Matter Power Spectrum ◽  
Small Scales ◽  
Λcdm Model ◽  
Equation Of State Parameter ◽  
Massive Neutrinos ◽  
Anomalous Growth

f(R) gravity provides viable cosmology alternative to the ΛCDM model. We discuss the effect of massive neutrinos on matter power spectrum in this theory, to show that the anomalous growth of density fluctuations on small scales due to the scalaron force can be compensated by free streaming of neutrinos. As a result, models which predict observable deviation of the equation-of-state parameter w DE from w DE = -1 may be reconciled with observations of matter clustering if the total neutrino mass is O(0.5 eV ).

scholarly journals PRISM: Sparse recovery of the primordial spectrum from WMAP9 and Planck datasets

2014 ◽  
Vol 10 (S306) ◽  
pp. 60-63
Author(s):  
P. Paykari ◽  
F. Lanusse ◽  
J.-L. Starck ◽  
F. Sureau ◽  
J. Bobin
Keyword(s):  
Inverse Problem ◽  
Power Spectrum ◽  
Structure Formation ◽  
Simulated Data ◽  
Inversion Method ◽  
Formation Mechanisms ◽  
Parametric Approach ◽  
Microwave Background ◽  
Scale Invariant ◽  
Primordial Power Spectrum

AbstractThe primordial power spectrum is an indirect probe of inflation or other structure-formation mechanisms. We introduce a new method, named PRISM, to estimate this spectrum from the empirical cosmic microwave background (CMB) power spectrum. This is a sparsity-based inversion method, which leverages a sparsity prior on features in the primordial spectrum in a wavelet dictionary to regularise the inverse problem. This non-parametric approach is able to reconstruct the global shape as well as localised features of the primordial spectrum accurately and proves to be robust for detecting deviations from the currently favoured scale-invariant spectrum. We investigate the strength of this method on a set of WMAP nine-year simulated data for three types of primordial spectra and then process the WMAP nine-year data as well as the Planck PR1 data. We find no significant departures from a near scale-invariant spectrum.

scholarly journals Early Structure Formation and Reionization in a Cosmological Model with a Running Primordial Power Spectrum

2003 ◽  
Vol 598 (1) ◽  
pp. 73-85 ◽  
Author(s):  
Naoki Yoshida ◽  
Aaron Sokasian ◽  
Lars Hernquist ◽  
Volker Springel
Keyword(s):  
Power Spectrum ◽  
Cosmological Model ◽  
Structure Formation ◽  
Primordial Power Spectrum
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