Scale-invariant density perturbations, anisotropy of the cosmic microwave background, and large-scale peculiar velocity field

1985 ◽  
Vol 293 ◽  
pp. L1 ◽  
Author(s):  
N. Vittorio ◽  
J. Silk
Keyword(s):  
Velocity Field ◽  
Cosmic Microwave Background ◽  
Large Scale ◽  
Invariant Density ◽  
Microwave Background ◽  
Scale Invariant ◽  
Peculiar Velocity ◽  
Density Perturbations

scholarly journals Large-scale peculiar velocities through the galaxy luminosity function at z ~ 0.1

2014 ◽  
Vol 11 (S308) ◽  
pp. 332-335
Author(s):  
Martin Feix ◽  
Adi Nusser ◽  
Enzo Branchini
Keyword(s):  
Velocity Field ◽  
Large Scale ◽  
Zero Point ◽  
Peculiar Velocity ◽  
Peculiar Velocities ◽  
The Galaxy ◽  
Linear Velocity Field ◽  
Density Perturbations ◽  
Velocity Moments ◽  
Galaxy Luminosity Function

AbstractPeculiar motion introduces systematic variations in the observed luminosity distribution of galaxies. This allows one to constrain the cosmic peculiar velocity field from large galaxy redshift surveys. Using around half a million galaxies from the SDSS Data Release 7 at z ~ 0.1, we demonstrate the applicability of this approach to large datasets and obtain bounds on peculiar velocity moments and σ8, the amplitude of the linear matter power spectrum. Our results are in good agreement with the ΛCDM model and consistent with the previously reported ~ 1% zero-point tilt in the SDSS photometry. Finally, we discuss the prospects of constraining the growth rate of density perturbations by reconstructing the full linear velocity field from the observed galaxy clustering in redshift space.

scholarly journals DENSITY PERTURBATIONS, GRAVITY WAVES AND THE COSMIC MICROWAVE BACKGROUND

1992 ◽  
Vol 07 (38) ◽  
pp. 3541-3551 ◽  
Author(s):  
TARUN SOURADEEP ◽  
VARUN SAHNI
Keyword(s):  
Cosmic Microwave Background ◽  
Gravity Waves ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Background Radiation ◽  
Density Perturbation ◽  
Microwave Background ◽  
Relative Contribution ◽  
Microwave Background Radiation ◽  
Density Perturbations

We assess the contribution to the observed large scale anisotropy of the cosmic microwave background radiation, arising from both gravity waves as well as adiabatic density perturbations, generated by a common inflationary mechanism in the early Universe. We find that for inflationary models predicting power law primordial spectra |δk|2∝kn, the relative contribution to the quadrupole anisotropy from gravity waves and scalar density perturbations, depends crucially upon n. For n<0.84, gravity waves perturb the CMBR by a larger amount than density perturbations, whereas for n>0.84 the reverse is true. Normalizing the amplitude of the density perturbation spectrum at large scales, using the observed value of the COBE quadrupole, we determine (δM/M)16-the rms density contrast on scales [Formula: see text] Mpc, for cosmological models with cold dark matter. We find that for n<0.75, a large amount of biasing is required in order to reconcile theory with observations. We also determine the value of the inflationary Hubble parameter and the COBE-normalized amplitude and spectrum of gravity waves from inflation.

scholarly journals Scale invariant density perturbations from cyclic cosmology

2016 ◽  
Vol 31 (13) ◽  
pp. 1650076 ◽  
Author(s):  
Paul Howard Frampton
Keyword(s):  
Large Scale ◽  
Quantum Fluctuations ◽  
Large Scale Structure ◽  
Density Fluctuations ◽  
Scale Structure ◽  
Invariant Density ◽  
Scale Invariant ◽  
Density Perturbations

It is shown how quantum fluctuations of the radiation during the contraction era of a comes back empty (CBE) cyclic cosmology can provide density fluctuations which re-enter the horizon during the subsequent expansion era and at lowest order are scale invariant, in a Harrison–Zel’dovich–Peebles sense. It is necessary to be consistent with observations of large scale structure.

scholarly journals Anisotropy of the Microwave Background and Biased Galaxy Formation

1988 ◽  
Vol 130 ◽  
pp. 43-50
Author(s):  
Nick Kaiser
Keyword(s):  
Galaxy Formation ◽  
Large Scale ◽  
Microwave Background ◽  
Galaxy Clustering ◽  
Clear View ◽  
Hot Gas ◽  
Density Perturbations ◽  
The Universe ◽  
Theoretical Developments

Fluctuations in the microwave background will have been imprinted at z ≃ 1000, when the photons and the plasma decoupled. On angular scales greater than a few degrees these fluctuations provide a clear view of any primordial density perturbations, and therefore a clean test of theories which invoke such fluctuations from which to form the structure we see in the universe. On smaller angular scales the predictions are less certain: reionization of the gas may modify the spectrum of the primordial fluctuations, and secondary fluctuations may be generated.Here I shall review some recent theoretical developments. A brief survey is made of the currently popular theories for the primordial perturbations, with emphasis on the predictions for large scale anisotropy. One major uncetainty in the predictions arises from the normalisation of the fluctuations to e.g. galaxy clustering, and much attention is given to the question of ‘biased’ galaxy formation. The effect of reionization on the primordial fluctuations is discussed, as is the anisotropy generated from scattering off hot gas in clusters, groups and galaxies.

Statistics of Cosmic Microwave Background Radiation with the Cosmic String Model

1997 ◽  
Vol 06 (05) ◽  
pp. 535-544
Author(s):  
Petri Mähönen ◽  
Tetsuya Hara ◽  
Toivo Voll ◽  
Shigeru Miyoshi
Keyword(s):  
Cosmic Microwave Background ◽  
Cosmic String ◽  
Large Scale ◽  
Background Radiation ◽  
Unit Length ◽  
Angular Size ◽  
Cosmic Microwave Background Radiation ◽  
Density Parameter ◽  
Microwave Background ◽  
Microwave Background Radiation

We have studied the cosmic microwave background radiation by simulating the cosmic string network induced anisotropies on the sky. The large-angular size simulations are based on the Kaiser–Stebbins effect calculated from full cosmic-string network simulation. The small-angular size simulations are done by Monte-Carlo simulation of perturbations from a time-discretized toy model. We use these results to find the normalization of μ, the string mass per unit length, and compare this result with one needed for large-scale structure formation. We show that the cosmic string scenario is in good agreement with COBE, SK94, and MSAM94 microwave background radiation experiments with reasonable string network parameters. The predicted rms-temperature fluctuations for SK94 and MSAM94 experiments are Δ T/T=1.57×10-5 and Δ T/T=1.62×10-5, respectively, when the string mass density parameter is chosen to be Gμ=1.4×10-6. The possibility of detecting non-Gaussian signals using the present day experiments is also discussed.

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