Large-scale structure of the Taurus molecular complex. I - Density fluctuations - A fossil Jeans length?

1984 ◽  
Vol 286 ◽  
pp. 255 ◽  
Author(s):  
S. C. Kleiner ◽  
R. L. Dickman
Keyword(s):  
Molecular Complex ◽  
Complex I ◽  
Large Scale ◽  
Large Scale Structure ◽  
Density Fluctuations ◽  
Scale Structure

scholarly journals Large Scale Structure of the Universe

1998 ◽  
Vol 179 ◽  
pp. 317-328 ◽  
Author(s):  
N.A. Bahcall
Keyword(s):  
Large Scale ◽  
Initial Conditions ◽  
Large Scale Structure ◽  
Density Fluctuations ◽  
Scale Structure ◽  
Sloan Digital Sky Survey ◽  
Sky Survey ◽  
Initial Spectrum ◽  
Formation And Evolution ◽  
The Universe

How is the universe organized on large scales? How did this structure evolve from the unknown initial conditions of a rather smooth early universe to the present time? The answers to these questions will shed light on the cosmology we live in, the amount, composition and distribution of matter in the universe, the initial spectrum of density fluctuations that gave rise to this structure, and the formation and evolution of galaxies, lusters of galaxies, and larger scale structures.To address these fundamental questions, large and accurate sky surveys are needed—in various wavelengths and to various depths. In this presentation I review current observational studies of large scale structure, present the constraints these observations place on cosmological models and on the amount of dark matter in the universe, and highlight some of the main unsolved problems in the field of large-scale structure that could be solved over the next decade with the aid of current and future surveys. I briefly discuss some of these surveys, including the Sloan Digital Sky Survey that will provide a complete imaging and spectroscopic survey of the high-latitude northern sky, with redshifts for the brightest ∼ 106 galaxies, 105 quasars, and 103.5 rich clusters of galaxies. The potentialities of the SDSS survey, as well as of cross-wavelength surveys, for resolving some of the unsolved problems in large-scale structure and cosmology are discussed.

scholarly journals Constraints on neutrino masses from the study of the nearby large-scale structure and galaxy cluster counts

2016 ◽  
Vol 31 (21) ◽  
pp. 1640008 ◽  
Author(s):  
Hans Böhringer ◽  
Gayoung Chon
Keyword(s):  
Large Scale ◽  
Cosmological Parameters ◽  
Large Scale Structure ◽  
Matter Density ◽  
Density Fluctuations ◽  
Scale Structure ◽  
Neutrino Masses ◽  
Microwave Background ◽  
X Ray ◽  
Massive Neutrinos

The high precision measurements of the cosmic microwave background by the Planck survey yielded tight constraints on cosmological parameters and the statistics of the density fluctuations at the time of recombination. This provides the means for a critical study of structure formation in the Universe by comparing the microwave background results with present epoch measurements of the cosmic large-scale structure. It can reveal subtle effects such as how different forms of Dark Matter may modify structure growth. Currently most interesting is the damping effect of structure growth by massive neutrinos. Different observations of low redshift matter density fluctuations provided evidence for a signature of massive neutrinos. Here we discuss the study of the cosmic large-scale structure with a complete sample of nearby, X-ray luminous clusters from our REFLEX cluster survey. From the observed X-ray luminosity function and its reproduction for different cosmological models, we obtain tight constraints on the cosmological parameters describing the matter density, [Formula: see text], and the density fluctuation amplitude, [Formula: see text]. A comparison of these constraints with the Planck results shows a discrepancy in the framework of a pure [Formula: see text]CDM model, but the results can be reconciled, if we allow for a neutrino mass in the range of 0.17 eV to 0.7 eV. Also some others, but not all of the observations of the nearby large-scale structure provide evidence or trends for signatures of massive neutrinos. With further improvement in the systematics and future survey projects, these indications will develop into a definitive measurement of neutrino masses.

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 Theories of Large Scale Structure

1988 ◽  
Vol 130 ◽  
pp. 273-280
Author(s):  
S. F. Shandarin
Keyword(s):  
Large Scale ◽  
Gravitational Instability ◽  
Large Scale Structure ◽  
Density Fluctuations ◽  
Weakly Interacting Massive Particles ◽  
Scale Structure ◽  
Main Process ◽  
Inflationary Model ◽  
Important Class ◽  
Gaussian Density

This talk is concerned with one of the most important class of theories of Large Scale Structure (hereafter LSS) based on two principal assumptions. It is supposed that (i) the main process is gravitational instability in expanding universe and (ii) the primordial perturbations a r e small Gaussian density fluctuations. Both assumptions are natural in inflationary model of the very early universe as well as in cosmological models dominated by Dark Matter (DM) in the form of Weakly Interacting Massive Particles (WIMPs). Other possible models of LSS formation are discussed by N. Turok, J. Ostriker and A. Dekel.

scholarly journals On the relative bias of void tracers in the Dark Energy Survey

2019 ◽  
Vol 487 (2) ◽  
pp. 2836-2852 ◽  
Author(s):  
G Pollina ◽  
N Hamaus ◽  
K Paech ◽  
K Dolag ◽  
J Weller ◽  
...  
Keyword(s):  
Dark Energy ◽  
Large Scale ◽  
Three Dimensional ◽  
Large Scale Structure ◽  
Density Fluctuations ◽  
Scale Structure ◽  
Relative Bias ◽  
Dark Energy Survey ◽  
Luminous Objects ◽  
Energy Survey

Abstract Luminous tracers of large-scale structure are not entirely representative of the distribution of mass in our Universe. As they arise from the highest peaks in the matter density field, the spatial distribution of luminous objects is biased towards those peaks. On large scales, where density fluctuations are mild, this bias simply amounts to a constant offset in the clustering amplitude of the tracer, known as linear bias. In this work we focus on the relative bias between galaxies and galaxy clusters that are located inside and in the vicinity of cosmic voids, extended regions of relatively low density in the large-scale structure of the Universe. With the help of mock data we verify that the relation between galaxy and cluster overdensity around voids remains linear. Hence, the void-centric density profiles of different tracers can be linked by a single multiplicative constant. This amounts to the same value as the relative linear bias between tracers for the largest voids in the sample. For voids of small sizes, which typically arise in higher density regions, this constant has a higher value, possibly showing an environmental dependence similar to that observed for the linear bias itself. We confirm our findings by analysing data obtained during the first year of observations by the Dark Energy Survey. As a side product, we present the first catalogue of three-dimensional voids extracted from a photometric survey with a controlled photo-z uncertainty. Our results will be relevant in forthcoming analyses that attempt to use voids as cosmological probes.

scholarly journals The cosmic web: a selective history and outlook

2014 ◽  
Vol 11 (S308) ◽  
pp. 125-142
Author(s):  
John A. Peacock
Keyword(s):  
Large Scale ◽  
Large Scale Structure ◽  
Matter Content ◽  
Density Fluctuations ◽  
Scale Structure ◽  
Central Importance ◽  
The Future ◽  
The Universe

AbstractIn the Century since Slipher's first observations, roughly three million galaxy redshifts have been measured. The resulting maps of large-scale structure have taught us much of central importance in cosmology, ranging from the matter content of the universe to the study of the primordial density fluctuations. This talk aims to review some of the key observational and theoretical milestones on this journey, and to speculate about what the future may bring.

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