scholarly journals Probing the Origins of Voids in the Distribution of Galaxies

2005 ◽  
Vol 22 (2) ◽  
pp. 166-173 ◽  
Author(s):  
Louise M. Ord ◽  
Martin Kunz ◽  
Hugues Mathis ◽  
Joseph Silk
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
External Source ◽  
Scientific Meeting ◽  
Acoustic Oscillations ◽  
De Sitter ◽  
Matter Distribution ◽  
Microwave Background ◽  
Sitter Background ◽  
Dark Matter Distribution

AbstractIf the voids that we see today in the distribution of galaxies existed at recombination, they will leave an imprint on the cosmic microwave background (CMB). On the other hand, if these voids formed much later, their effect on the CMB will be negligible and will not be observed with the current generation of experiments. In this paper, presented at the 2004 Annual Scientific Meeting of the Astronomical Society of Australia, we discuss our ongoing investigations into voids of primordial origin. We show that if voids in the cold dark matter distribution existed at the epoch of decoupling, they could contribute significantly to the apparent rise in CMB power on small scales detected by the Cosmic Background Imager (CBI) Deep Field. Here we present our improved method for predicting the effects of primordial voids on the CMB in which we treat a void as an external source in the cold dark matter (CDM) distribution employing a Boltzmann solver. Our improved predictions include the effects of a cosmological constant (Λ) and acoustic oscillations generated by voids at early times. We find that models with relatively large voids on the last scattering surface predict too much CMB power in an Einstein–de Sitter background cosmology but could be consistent with the current CMB observations in a ΛCDM universe.

scholarly journals The Dark Matter Distribution in the Central Regions of Galaxy Clusters: Implications for Cold Dark Matter

2004 ◽  
Vol 604 (1) ◽  
pp. 88-107 ◽  
Author(s):  
David J. Sand ◽  
Tommaso Treu ◽  
Graham P. Smith ◽  
Richard S. Ellis
Keyword(s):  
Dark Matter ◽  
Galaxy Clusters ◽  
Cold Dark Matter ◽  
Matter Distribution ◽  
Central Regions ◽  
Dark Matter Distribution

scholarly journals Testing the warmness of dark matter

2019 ◽  
Vol 490 (1) ◽  
pp. 1406-1414 ◽  
Author(s):  
Suresh Kumar ◽  
Rafael C Nunes ◽  
Santosh Kumar Yadav
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Hubble Space Telescope ◽  
Hubble Constant ◽  
Mass Scale ◽  
Acoustic Oscillations ◽  
Microwave Background ◽  
Mean Values ◽  
Λcdm Model ◽  
Cosmological Data

ABSTRACT Dark matter (DM) as a pressureless perfect fluid provides a good fit of the standard Λ cold dark matter (ΛCDM) model to the astrophysical and cosmological data. In this paper, we investigate two extended properties of DM: a possible time dependence of the equation of state of DM via Chevallier–Polarski–Linder parametrization, wdm = wdm0 + wdm1(1 − a), and the constant non-null sound speed $\hat{c}^2_{\rm s,dm}$. We analyse these DM properties on top of the base ΛCDM model by using the data from Planck cosmic microwave background (CMB) temperature and polarization anisotropy, baryonic acoustic oscillations (BAOs), and the local value of the Hubble constant from the Hubble Space Telescope (HST). We find new and robust constraints on the extended free parameters of DM. The most tight constraints are imposed by CMB+BAO data, where the three parameters wdm0, wdm1, and $\hat{c}^2_{\rm s,dm}$ are, respectively, constrained to be less than 1.43 × 10−3, 1.44 × 10−3, and 1.79 × 10−6 at 95 per cent CL. All the extended parameters of DM show consistency with zero at 95 per cent CL, indicating no evidence beyond the CDM paradigm. We notice that the extended properties of DM significantly affect several parameters of the base ΛCDM model. In particular, in all the analyses performed here, we find significantly larger mean values of H0 and lower mean values of σ8 in comparison to the base ΛCDM model. Thus, the well-known H0 and σ8 tensions might be reconciled in the presence of extended DM parameters within the ΛCDM framework. Also, we estimate the warmness of DM particles as well as its mass scale, and find a lower bound: ∼500 eV from our analyses.

scholarly journals Combining Probes

2014 ◽  
Vol 10 (S306) ◽  
pp. 192-201
Author(s):  
Anaïs Rassat ◽  
François Lanusse ◽  
Donnacha Kirk ◽  
Ole Host ◽  
Sarah Bridle
Keyword(s):  
Dark Matter ◽  
Cosmological Parameters ◽  
Fundamental Aspect ◽  
Wide Field ◽  
Matter Distribution ◽  
Microwave Background ◽  
Field Surveys ◽  
Galaxy Surveys ◽  
Dark Matter Distribution ◽  
Combining Information

AbstractWith the advent of wide-field surveys, cosmology has entered a new golden age of data where our cosmological model and the nature of dark universe will be tested with unprecedented accuracy, so that we can strive for high precision cosmology. Observational probes like weak lensing, galaxy surveys and the cosmic microwave background as well as other observations will all contribute to these advances. These different probes trace the underlying expansion history and growth of structure in complementary ways and can be combined in order to extract cosmological parameters as best as possible. With future wide-field surveys, observational overlap means these will trace the same physical underlying dark matter distribution, and extra care must be taken when combining information from different probes. Consideration of probe combination is a fundamental aspect of cosmostatistics and important to ensure optimal use of future wide-field surveys.

The Future of Dwarf Galaxy Research: What Simulations will Predict?

2018 ◽  
Vol 14 (S344) ◽  
pp. 17-26
Author(s):  
Laura V. Sales
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Cold Dark Matter ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Matter Content ◽  
Dark Matter Halos ◽  
Matter Distribution ◽  
The Future ◽  
Dark Matter Distribution

AbstractWe present a summary of the predictions from numerical simulations to our understanding of dwarf galaxies. It centers the discussion around the Λ Cold Dark Matter scenario (ΛCDM) but discusses also implications for alternative dark matter models. Four key predictions are identified: the abundance of dwarf galaxies, their dark matter content, their relation with environment and the existence of dwarf satellites orbiting dwarf field galaxies. We discuss tensions with observations and identify the most exciting predictions expected from simulations in the future, including i) the existence of “dark galaxies” (dark matter halos without stars), ii) the ability to resolve the structure (size, morphology, dark matter distribution) in dwarfs and iii) the number of ultra-faint satellites around dwarf galaxies. All of these predictions shall inform future observations, not only the faintest galaxies to be discovered within the Local Volume but also distant dwarfs driving galaxy formation in the early universe.

Interpreting deviations between AR-VTG and GR

2019 ◽  
Vol 28 (01) ◽  
pp. 1930002
Author(s):  
Roberto Dale ◽  
Diego Sáez
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Microwave Background ◽  
Tensor Theory ◽  
Cosmological Observations ◽  
The Standard Model ◽  
Cross Correlations ◽  
Theory Of Gravitation ◽  
Dark Matter Distribution

The cosmic microwave background (CMB) anisotropies predicted by two cosmological models are compared, one of them is the standard model of general relativity with cold dark matter and cosmological constant, whereas the second model is based on a consistent vector-tensor theory of gravitation explaining solar system and cosmological observations. It is proved that the resulting differences — between the anisotropies of both models — are due to the so-called late integrated Sachs–Wolfe effect and, consequently, cross-correlations between maps of CMB temperatures and tracers of the dark matter distribution could be used in future to select one of the above models. The role of reionization is analyzed in detail.

scholarly journals DARK MATTER DYNAMICS AND INDIRECT DETECTION

2005 ◽  
Vol 20 (14) ◽  
pp. 1021-1036 ◽  
Author(s):  
GIANFRANCO BERTONE ◽  
DAVID MERRITT
Keyword(s):  
Dark Matter ◽  
Total Mass ◽  
Galactic Center ◽  
Direct Detection ◽  
Indirect Detection ◽  
Matter Distribution ◽  
Dark Matter Distribution ◽  
Particle Dark Matter ◽  
The Universe ◽  
Rule Out

Non-baryonic, or "dark", matter is believed to be a major component of the total mass budget of the Universe. We review the candidates for particle dark matter and discuss the prospects for direct detection (via interaction of dark matter particles with laboratory detectors) and indirect detection (via observations of the products of dark matter self-annihilations), focusing in particular on the Galactic center, which is among the most promising targets for indirect detection studies. The gravitational potential at the Galactic center is dominated by stars and by the supermassive black hole, and the dark matter distribution is expected to evolve on sub-parsec scales due to interaction with these components. We discuss the dominant interaction mechanisms and show how they can be used to rule out certain extreme models for the dark matter distribution, thus increasing the information that can be gleaned from indirect detection searches.

scholarly journals Dark matter distribution induced by a cosmic string wake in the nonlinear regime

2018 ◽  
Vol 98 (8) ◽  
Author(s):  
Disrael Camargo Neves da Cunha ◽  
Joachim Harnois-Deraps ◽  
Robert Brandenberger ◽  
Adam Amara ◽  
Alexandre Refregier
Keyword(s):  
Dark Matter ◽  
Cosmic String ◽  
Nonlinear Regime ◽  
Matter Distribution ◽  
Dark Matter Distribution
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