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 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 Clustering and halo abundances in early dark energy cosmological models

2021 ◽  
Vol 504 (1) ◽  
pp. 769-781
Author(s):  
Anatoly Klypin ◽  
Vivian Poulin ◽  
Francisco Prada ◽  
Joel Primack ◽  
Marc Kamionkowski ◽  
...  
Keyword(s):  
Dark Energy ◽  
Cold Dark Matter ◽  
Power Spectra ◽  
Hubble Constant ◽  
Cosmological Models ◽  
Acoustic Oscillations ◽  
Microwave Background ◽  
Linear Evolution ◽  
James Webb Space Telescope ◽  
Non Linear

ABSTRACT Cold Dark Matter with cosmological constant (ΛCDM) cosmological models with early dark energy (EDE) have been proposed to resolve tensions between the Hubble constant $H_0=100\, h$ km ṡ−1Ṁpc−1 measured locally, giving h ≈ 0.73, and H0 deduced from Planck cosmic microwave background (CMB) and other early-Universe measurements plus ΛCDM, giving h ≈ 0.67. EDE models do this by adding a scalar field that temporarily adds dark energy equal to about 10 per cent of the cosmological energy density at the end of the radiation-dominated era at redshift z ∼ 3500. Here, we compare linear and non-linear predictions of a Planck-normalized ΛCDM model including EDE giving h = 0.728 with those of standard Planck-normalized ΛCDM with h = 0.678. We find that non-linear evolution reduces the differences between power spectra of fluctuations at low redshifts. As a result, at z = 0 the halo mass functions on galactic scales are nearly the same, with differences only 1–2 per cent. However, the differences dramatically increase at high redshifts. The EDE model predicts 50 per cent more massive clusters at z = 1 and twice more galaxy-mass haloes at z = 4. Even greater increases in abundances of galaxy-mass haloes at higher redshifts may make it easier to reionize the universe with EDE. Predicted galaxy abundances and clustering will soon be tested by the James Webb Space Telescope (JWST) observations. Positions of baryonic acoustic oscillations (BAOs) and correlation functions differ by about 2 per cent between the models – an effect that is not washed out by non-linearities. Both standard ΛCDM and the EDE model studied here agree well with presently available acoustic-scale observations, but the Dark Energy Spectroscopic Instrument and Euclid measurements will provide stringent new tests.

8. Space telescopes

2016 ◽  
pp. 96-121
Author(s):  
Geoff Cottrell
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Gamma Ray ◽  
Background Radiation ◽  
Hubble Space Telescope ◽  
Space Telescopes ◽  
Microwave Background ◽  
Microwave Background Radiation ◽  
Standard Cosmological Model ◽  
Unknown Form

The last seven decades have seen telescopes launched into space, vastly enhancing the crispness of the images they produce and expanding the range of observable wavelengths to include UV, X- and gamma-ray wavelengths. ‘Space telescopes’ shows how the information gleaned from them has enabled us to make new discoveries and form much more complete astrophysical models. It documents the development of space telescopes—including the Hubble Space Telescope—and highlights key discoveries, such as cosmic microwave background radiation, the results of which have profound implications for cosmology. The Standard Cosmological Model is known as ‘lambda cold dark matter’, containing three main ingredients: baryonic matter, cold dark matter (the unknown form of gravitating matter), and the mysterious dark energy.

scholarly journals The Hot Big Bang and Beyond

1996 ◽  
Vol 168 ◽  
pp. 301-320
Author(s):  
Michael S. Turner
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Hubble Space Telescope ◽  
Hubble Constant ◽  
Big Bang ◽  
Small Admixture ◽  
Matter Theory ◽  
Density Perturbations ◽  
The Big Bang ◽  
The Universe

The hot big-bang cosmology provides a reliable accounting of the Universe from about 10−2sec after the bang until the present, as well as a robust framework for speculating back to times as early as 10−43sec. Cosmology faces a number of important challenges; foremost among them are determining the quantity and composition of matter in the Universe and developing a detailed and coherent picture of how structure (galaxies, clusters of galaxies, superclusters, voids, great walls, and so on) developed. At present there is a working hypothesis—cold dark matter—which is based upon inflation and which, if correct, would extend the big bang model back to 10−32sec and cast important light on the unification of the forces. Many experiments and observations, from CBR anisotropy experiments to Hubble Space Telescope observations to experiments at Fermilab and CERN, are now putting the cold dark matter theory to the test. At present it appears that the theory is viable only if the Hubble constant is smaller than current measurements indicate (around 30 km s−1Mpc−1), or if the theory is modified slightly, e.g., by the addition of a cosmological constant, a small admixture of hot dark matter (5 eV “worth of neutrinos”), more relativistic particles, or a tilted spectrum of density perturbations.

Ω0 Concordance

2005 ◽  
Vol 201 ◽  
pp. 271-281
Author(s):  
Masataka. Fukugita
Keyword(s):  
Dark Matter ◽  
Cosmological Constant ◽  
Structure Formation ◽  
Cold Dark Matter ◽  
Mass Density ◽  
Hubble Constant ◽  
Density Parameter ◽  
Microwave Background ◽  
The Hierarchical Structure ◽  
The Universe

The determinations of the mass density parameter Ω0 are examined with a particular emphasis given to the new cosmic microwave background (CMB) experiments. It is shown that the Ω0 and the Hubble constant H0 from CMB are quite consistent with those from other observations with the aid of the hierarchical structure formation models based on cold dark matter dominance with the cosmological constant that makes the universe flat. The concordance value of Ω0 is 0.25-0.45.

scholarly journals Testing a quintessence model with Yukawa interaction from cosmological observations and N-body simulations

2019 ◽  
Vol 489 (1) ◽  
pp. 297-309 ◽  
Author(s):  
Rui An ◽  
André A Costa ◽  
Linfeng Xiao ◽  
Jiajun Zhang ◽  
Bin Wang
Keyword(s):  
Dark Matter ◽  
Gravitational Lensing ◽  
Cold Dark Matter ◽  
Interaction Model ◽  
Yukawa Interaction ◽  
Dark Sector ◽  
Microwave Background ◽  
Cosmological Observations ◽  
Cosmological Data ◽  
Quintessence Model

ABSTRACT We consider a quintessence model with Yukawa interaction between dark energy and dark matter and constrain this model by employing the recent cosmological data including the updated cosmic microwave background (CMB) measurements from Planck 2015, the weak gravitational lensing measurements from Kilo Degree Survey (KiDS), and redshift-space distortions. We find that an interaction in the dark sector is compatible with observations. The updated Planck data can significantly improve the constraints compared with the previous results from Planck 2013, while the KiDS data have less constraining power than Planck. The Yukawa interaction model is found to be moderately favoured by Planck and able to alleviate the discordance between weak lensing measurements and CMB measurements as previously inferred from the standard Lambda cold dark matter model. N-body simulations for Yukawa interaction model is also performed. We find that using the halo density profile is plausible to improve the constraints significantly in the future.

scholarly journals Cosmic Microwave Background as a Thermal Gas of SU(2) Photons: Implications for the High-z Cosmological Model and the Value of H0

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Steffen Hahn ◽  
Ralf Hofmann
Keyword(s):  
Dark Matter ◽  
Cosmological Model ◽  
Cosmic Microwave Background ◽  
Cold Dark Matter ◽  
Formal Solution ◽  
Planck Scale ◽  
Low Frequency ◽  
Hubble Constant ◽  
Microwave Background ◽  
Photon Gas

Presently, we are facing a 3σ tension in the most basic cosmological parameter, the Hubble constant H0. This tension arises when fitting the Lambda-cold-dark-matter model (ΛCDM) to the high-precision temperature-temperature (TT) power spectrum of the Cosmic Microwave Background (CMB) and to local cosmological observations. We propose a resolution of this problem by postulating that the thermal photon gas of the CMB obeys an SU(2) rather than U(1) gauge principle, suggesting a high-z cosmological model which is void of dark-matter. Observationally, we rely on precise low-frequency intensity measurements in the CMB spectrum and on a recent model independent (low-z) extraction of the relation between the comoving sound horizon rs at the end of the baryon drag epoch and H0 (rsH0=const). We point out that the commonly employed condition for baryon-velocity freeze-out is imprecise, judged by a careful inspection of the formal solution to the associated Euler equation. As a consequence, the above-mentioned 3σ tension actually transforms into a 5σ discrepancy. To make contact with successful low-z  ΛCDM cosmology we propose an interpolation based on percolated/depercolated vortices of a Planck-scale axion condensate. For a first consistency test of such an all-z model we compute the angular scale of the sound horizon at photon decoupling.

scholarly journals Bayesian comparison of interacting modified holographic Ricci dark energy scenarios

2021 ◽  
Vol 81 (1) ◽  
Author(s):  
Antonella Cid ◽  
Carlos Rodriguez-Benites ◽  
Mauricio Cataldo ◽  
Gonzalo Casanova
Keyword(s):  
Dark Energy ◽  
Hubble Constant ◽  
Joint Analysis ◽  
Acoustic Oscillations ◽  
Microwave Background ◽  
Ricci Dark Energy ◽  
Type Ia ◽  
Cosmological Data ◽  
Ia Supernovae ◽  
Local Value

AbstractWe perform a Bayesian model selection analysis for interacting scenarios of dark matter and modified holographic Ricci dark energy (MHRDE) with linear interacting terms. We use a combination of some of the latest cosmological data such as type Ia supernovae, cosmic chronometers, the local value of the Hubble constant, baryon acoustic oscillations measurements and cosmic microwave background through the angular scale of the sound horizon at last scattering. We find moderate/strong evidence against all the MHRDE interacting scenarios studied with respect to $$\Lambda $$ Λ CDM when the full joint analysis is considered.

scholarly journals New constraint of the Hubble constant by proper motions of radio components observed in AGN twin-jets

2021 ◽  
Vol 21 (10) ◽  
pp. 261
Author(s):  
Wei-Jian Lu ◽  
Yi-Ping Qin
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Hubble Constant ◽  
Proper Motions ◽  
Microwave Background ◽  
Background Data ◽  
Local Distance ◽  
Twin Jets ◽  
Real Value ◽  
Cosmic Microwave Background Data

Abstract As the advent of precision cosmology, the Hubble constant (H 0) inferred from the Lambda Cold Dark Matter fit to the Cosmic Microwave Background data is increasingly in tension with the measurements from the local distance ladder. To approach its real value, we need more independent methods to measure, or to make constraint of, the Hubble constant. In this paper, we apply a plain method, which is merely based on the Friedman-Lemaître-Robertson-Walker cosmology together with geometrical relations, to constrain the Hubble constant by proper motions of radio components observed in AGN twin-jets. Under the assumption that the ultimate ejection strengths in both sides of the twin-jet concerned are intrinsically the same, we obtain a lower limit of H 0,min = 51.5 ± 2.3 km s−1 Mpc−1 from the measured maximum proper motions of the radio components observed in the twin-jet of NGC 1052.

DYNAMICS AND THE SECOND PEAK: COLD DARK MATTER?

2001 ◽  
Vol 16 (supp01c) ◽  
pp. 1031-1033 ◽  
Author(s):  
STACY MCGAUGH
Keyword(s):  
Dark Matter ◽  
Power Spectrum ◽  
Cold Dark Matter ◽  
Background Radiation ◽  
Angular Spectrum ◽  
Microwave Background ◽  
Λcdm Model ◽  
Microwave Background Radiation ◽  
Second Peak ◽  
Modified Dynamics

The amplitude of the second peak in the angular spectrum of the cosmic microwave background radiation is constrained to be small by recent experiments like Boomerang. This is surprising in the context of the ΛCDM model, which predicted a large second peak. However, this result is expected if CDM does not exist. The observed shape of the power spectrum was accurately predicted (before the fact) by a model motivated by the surprising recent successes of the modified dynamics (MOND) hypothesized by Milgrom.

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