scholarly journals Dark Matter in the Universe

BIBECHANA ◽  
1970 ◽  
Vol 6 ◽  
pp. 27-30
Author(s):  
Devendra Adhikari ◽  
Krishna Raj Adhikari
Keyword(s):  
Dark Matter ◽  
Baryonic Matter ◽  
X Ray ◽  
Physical Phenomena ◽  
The Universe

Different physical phenomena, techniques, and evidences which give the proof for the existence of dark matter have been discussed. Keywords: Baryonic matter; dark matter; Chandra x-ray ObservatoryDOI: 10.3126/bibechana.v6i0.3936BIBECHANA Vol. 6, March 2010 pp.27-30

scholarly journals On The Symmetry of The Universe

2020 ◽  
Author(s):  
Engel Roza
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Thermodynamic Equilibrium ◽  
Vacuum Energy ◽  
Quantum Mechanical ◽  
Baryonic Matter ◽  
Time Uncertainty ◽  
Matter Effect ◽  
Mechanical Interpretation ◽  
The Universe

It is shown that the Lambda component in the cosmological Lambda-CDM model can be conceived as vacuum energy, consisting of gravitational particles subject to Heisenberg’s energy-time uncertainty. These particles can be modelled as elementary polarisable Dirac-type dipoles (“darks”) in a fluidal space at thermodynamic equilibrium, with spins that are subject to the Bekenstein-Hawking entropy. Around the baryonic kernels, uniformly distributed in the universe, the spins are polarized, thereby invoking an increase of the effective gravitational strength of the kernels. It explains the dark matter effect to the extent that the numerical value of Milgrom’s acceleration constant can be assessed by theory. Non-polarized vacuum particles beyond the baryonic kernels compose the dark energy. The result is a quantum mechanical interpretation of gravity in terms of quantitatively established shares in baryonic matter, dark matter and dark energy, which correspond with the values of the Lambda-CDM model..

NONLINEAR EVOLUTION OF COSMIC BARYON FLUID

2012 ◽  
Vol 12 ◽  
pp. 120-130
Author(s):  
LI-ZHI FANG
Keyword(s):  
Dark Matter ◽  
Gravitational Field ◽  
Velocity Field ◽  
Nonlinear Evolution ◽  
Statistical Properties ◽  
Complex Structures ◽  
Baryonic Matter ◽  
Developed Turbulence ◽  
Highly Nonlinear ◽  
The Universe

Although the gravitational field in the universe is dominated by dark matter, observations show that the statistical properties of cosmic baryonic matter are significantly and systematically decoupled from that of the underlying dark matter. This is because the cosmic baryon fluid in highly nonlinear regime is in a state of fully developed turbulence, of which the velocity field consists of shocks, vortices and complex structures. This scenario provides a coherent explanation of various phenomena referring to the decoupling of the IGM from dark matter, including the log-Poisson non-Gaussianity of Ly-alpha transmitted flux fluctuations; turbulent broadening; abnormal scaling; baryon missing in halos etc.

scholarly journals Evolution of Primordial Dark Matter Planets in the Early Universe

2020 ◽  
Author(s):  
Arun Kenath ◽  
Kiren O. V. ◽  
Sivaram C
Keyword(s):  
Dark Matter ◽  
Neutron Stars ◽  
Early Universe ◽  
Critical Thickness ◽  
Nuclear Reactions ◽  
Compact Objects ◽  
X Ray ◽  
Primordial Planets ◽  
The Universe ◽  
Observational Signature

In a recent paper we had discussed possibility of DM at high redshifts forming primordial planets composed entirely of DM to be one of the reasons for not detecting DM (as the flux of ambient DM particles would be consequently reduced). In this paper we discuss the evolution of these DM objects as the universe expands. As universe expands there will be accretion of DM, Helium and Hydrogen layers (discussed in detail) on these objects. As they accumulate more and more mass, the layers get heated up leading to nuclear reactions which burn H and He when a critical thickness is reached. In the case of heavier masses of these DM objects, matter can be ejected explosively. It is found that the time scale of ejection is smaller than those from other compact objects like neutron stars (that lead to x-ray bursts). These flashes of energy could be a possible observational signature for these dense DM objects.

scholarly journals Dark Matter in Groups and Clusters of Galaxies

2000 ◽  
Vol 174 ◽  
pp. 360-372 ◽  
Author(s):  
Jaan Einasto ◽  
Maret Einasto
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Dynamical Evolution ◽  
Constant Term ◽  
Stellar Populations ◽  
Clusters Of Galaxies ◽  
Baryonic Matter ◽  
Dark Matter Halos ◽  
Hot Gas ◽  
The Universe

AbstractWe compare the characteristics of stellar populations with those of dark halos. Dark matter around galaxies, and in groups, clusters and voids is discussed. Modern data suggest that the overall density of matter in the Universe is ΩM = 0.3 ± 0.1, about 80 % of this matter is nonbaryonic dark matter, and about 20 % is baryonic, mostly in the form of hot intra-cluster and intragroup gas, the rest in stellar populations of galaxies. All bright galaxies are surrounded by dark matter halos of external radii 200 − 300 kpc; halos consist mostly of non-baryonic matter with some mixture of hot gas. The Universe is dominated by dark energy (cosmological constant) term. Dark matter dominates in the dynamical evolution of galaxies in groups and clusters.

scholarly journals A Cosmological View on Milgrom’s Acceleration Constant

2017 ◽  
Author(s):  
Engel Roza
Keyword(s):  
Dark Matter ◽  
Baryonic Matter ◽  
Stellar Rotation ◽  
Adequate Explanation ◽  
Cosmological Time ◽  
Acceleration Parameter ◽  
Age Of The Universe ◽  
Two Parameters ◽  
The Universe ◽  
Two Parameter

In this article a two-parameter model is developed for the universe. The two parameters are the age of the universe and the value of Einstein’s Cosmological Constant. It is shown that these are sufficient to calculate the amounts of matter and dark energy in the universe, as well as the contributions of dark matter and baryonic matter in the matter part. All this, not only for present time, but also as a function of cosmological time. Moreover, the model allows establishing the numerical value for Milgrom’s acceleration parameter for present time. The developed theory gives an adequate explanation for the phenomena of the accelerated scaling of the universe and the anomaly of the stellar rotation curves in galaxies. The numerical results are in agreement with those of the Lamda-CDM model.

scholarly journals A Cosmological View on Milgrom’s Acceleration Constant

2018 ◽  
Author(s):  
Engel Roza
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Baryonic Matter ◽  
Stellar Rotation ◽  
Adequate Explanation ◽  
Cosmological Time ◽  
Age Of The Universe ◽  
Two Parameters ◽  
The Universe ◽  
Two Parameter

In this article a two-parameter model is developed for the universe. The two parameters are the age of the universe and Milgrom’s acceleration constant. It is shown that these are sufficient to calculate the amounts of matter and dark energy in the universe, as well as the contributions of dark matter and baryonic matter in the matter part. All this, not only for present time, but also as a function of cosmological time. The developed theory gives an adequate explanation for the phenomena of the accelerated scaling of the universe and the anomaly of the stellar rotation curves in galaxies. The numerical results are in agreement with those of the Lamda-CDM model.

scholarly journals Statistical and Dynamical Decoupling of the IGM from Dark Matter

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Li-Zhi Fang ◽  
Weishan Zhu
Keyword(s):  
Dark Matter ◽  
Complex Structures ◽  
Baryonic Matter ◽  
Dynamical Decoupling ◽  
Scale Free ◽  
Developed Turbulence ◽  
Cosmological Observations ◽  
Highly Nonlinear ◽  
The Difference ◽  
The Universe

Although the gravitational field in the universe is dominated by dark matter, cosmological observations show that the statistical properties of cosmic baryonic matter are significantly and systematically decoupled from that of the underlying dark matter. The dynamical reason of the decoupling is the difference of the nonlinear evolution of baryon fluid from that of collisionless dark matter. In highly nonlinear regime, the cosmic baryon fluid on scale free range evolves into the state of fully developed turbulence, of which the velocity field consists of shocks, vortices and complex structures. This scenario provides a coherent explanation of various phenomena referring to the statistical and dynamical decoupling of the IGM from dark matter.

scholarly journals The Distribution Of Dark Mass In Galaxies

1996 ◽  
Vol 173 ◽  
pp. 165-174 ◽  
Author(s):  
Penny D. Sackett
Keyword(s):  
Dark Matter ◽  
Temperature Profile ◽  
Gravitational Lensing ◽  
Milky Way ◽  
Stellar Kinematics ◽  
X Ray ◽  
Neutral Gas ◽  
Complementary Techniques ◽  
Gas Layer ◽  
The Universe

Gravitational lensing is one of a number of methods used to probe the distribution of dark mass in the Universe. On galactic scales, complementary techniques include the use of stellar kinematics, the kinematics and morphology of the neutral gas layer, kinematics of satellites, and the morphology and temperature profile of X-ray halos. These methods are compared, with emphasis on their relative strengths and weaknesses in constraining the distribution and extent of dark matter in the Milky Way and other galaxies. It is concluded that (1) the extent of dark halos remains ill-constrained, (2) halos need not be isothermal, and (3) the dark mass is probably quite flattened.

scholarly journals Clustering of X-Ray-Selected AGN

2012 ◽  
Vol 2012 ◽  
pp. 1-19 ◽  
Author(s):  
N. Cappelluti ◽  
V. Allevato ◽  
A. Finoguenov
Keyword(s):  
Dark Matter ◽  
Spatial Distribution ◽  
Galaxy Evolution ◽  
Dark Matter Halos ◽  
Galaxy Mergers ◽  
X Ray ◽  
Galaxy Groups ◽  
Two Generations ◽  
The Times ◽  
The Universe

The study of the angular and spatial structure of the X-ray sky has been under investigation since the times of theEinsteinX-ray Observatory. This topic has fascinated more than two generations of scientists and slowly unveiled an unexpected scenario regarding the consequences of the angular and spatial distribution of X-ray sources. It was first established from the clustering of sources making the CXB that the source spatial distribution resembles that of optical QSO. It then became evident that the distribution of X-ray AGN in the Universe was strongly reflecting that of Dark Matter. In particular, one of the key results is that X-ray AGNs are hosted by dark matter halos of mass similar to that of galaxy groups. This result, together with model predictions, has lead to the hypothesis that galaxy mergers may constitute the main AGN-triggering mechanism. However, detailed analysis of observational data, acquired with modern telescopes, and the use of the new halo occupation formalism has revealed that the triggering of an AGN could also be attributed to phenomena-like tidal disruption or disk instability and to galaxy evolution. This paper reviews results from 1988 to 2011 in the field of X-ray-selected AGN clustering.

scholarly journals Clusters of Galaxies in a Flat CHDM Universe

1998 ◽  
Vol 188 ◽  
pp. 299-299
Author(s):  
A. Habe ◽  
C. Hanyu ◽  
S. Yachi
Keyword(s):  
Dark Matter ◽  
Large Scale ◽  
Large Scale Structure ◽  
Numerical Results ◽  
Clusters Of Galaxies ◽  
Statistical Features ◽  
X Ray ◽  
Numerical Resolution ◽  
Radiative Processes ◽  
The Universe

Cold and hot dark matter (CHDM) model is one of viable models which can reproduce the large scale structure of the universe. HDM may affect structure of clusters of galaxies in CHDM universe. Bryan et al. (1994) gave numerical results of CHDM model that explain some statistical features of X-ray clusters of galaxies, e.g. X-ray luminosiry-temperature realtion, L ∝~ T3.5, without considering radiative processes. However their numerical resolution is insufficient to resolve the cores of X-ray clusters. So, we simulate the formation of clusters in CHDM universe more carefully.

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