The virial mass discrepancy in groups and clusters of galaxies

1978 ◽  
Vol 219 ◽  
pp. 345 ◽  
Author(s):  
F. D. A. Hartwick
Keyword(s):  
Clusters Of Galaxies ◽  
Virial Mass

scholarly journals Photons in Curved Space?Time

1987 ◽  
Vol 40 (3) ◽  
pp. 449 ◽  
Author(s):  
David F Crawford
Keyword(s):  
Energy Loss ◽  
Loss Rate ◽  
Hubble Constant ◽  
Space Time ◽  
Quantum Mechanical ◽  
Clusters Of Galaxies ◽  
Hydrogen Atoms ◽  
Curved Space ◽  
Universal Expansion ◽  
Virial Mass

Because photons are described by quantum mechanical wavefunctions that have a nonzero spatial extent it follows that they can be influenced by curved space-time. It is generally assumed that this tidal interaction is far too small to have a significant effect. This paper argues that there is a significant effect that results in an interaction between the photon and the material causing the curved space-time in which the photon loses energy to low energy secondary photons. The energy loss is a function of the space-time curvature and is proportional to distance. The only situation fully considered is that of a photon in curved space-time due to a uniform distribution of matter. Because the energy loss rate is very small it is difficult to observe in the laboratory and therefore its major applications are in astronomy. If the intergalactic density of matter is n hydrogen atoms m - 3, then the predicted value for the 'Hubble' constant (assuming no universal expansion) is 51�68 n1 /2 km s - 1 Mpc - 1. The theory can solve the virial mass discrepancy observed in clusters of galaxies and it makes a definite prediction about their relative magnitudes. Other astronomical applications are considered.

scholarly journals Dark Matter in Groups and Clusters of Galaxies

1995 ◽  
Vol 164 ◽  
pp. 454-454
Author(s):  
M. Kalinkov ◽  
I. Kuneva ◽  
I. Valtchanov
Keyword(s):  
Line Of Sight ◽  
Clusters Of Galaxies ◽  
Dynamical Models ◽  
Dynamical Characteristics ◽  
Velocity Statistics ◽  
Total Luminosity ◽  
Crossing Time ◽  
Pair Separation ◽  
Virial Mass ◽  
Harmonic Radius

Samples of groups, clusters and superclusters of galaxies have been collected from existing catalogs. The group sample consisted of 70 systems, the list of clusters contains 50 systems, and there are five superclusters. Kinematical and dynamical characteristics are obtained — elongation (along the line of sight, RA and Dec), velocity statistics, total luminosity, harmonic radius, mean pair separation, crossing time, virial mass … We have compared some of the observational features with dynamical models of groups, clusters and superclusters. Aarseth's (1985) code is used.

On the Evolution of the Temperature–Virial Mass Relation for Clusters of Galaxies

1998 ◽  
Vol 500 (2) ◽  
pp. L111-L114 ◽  
Author(s):  
G. Mark Voit ◽  
Megan Donahue
Keyword(s):  
Mass Relation ◽  
Clusters Of Galaxies ◽  
Virial Mass

scholarly journals THE LARGEST VIRIALIZED DARK HALO IN THE UNIVERSE

2002 ◽  
Vol 11 (08) ◽  
pp. 1189-1193
Author(s):  
WEI ZHOU ◽  
TONG-JIE ZHANG ◽  
LI CHEN ◽  
XIANG-TAO HE ◽  
YU-MEI HUANG
Keyword(s):  
Structure Formation ◽  
Temperature Increase ◽  
Analytic Approach ◽  
Dark Halo ◽  
Clusters Of Galaxies ◽  
Λcdm Model ◽  
Present Universe ◽  
Virial Mass ◽  
The Universe ◽  
Rule Out

Using semi-analytic approach, we present an estimate of the properties of the largest virialized dark halos in the present universe for three different scenarios of structure formation: SCDM, ΛCDM and OCDM models. The resulting virial mass and temperature increase from the lowest values of 1.6 × 1015 h-1 M⊙ and 9.8 keV in OCDM, the mid-range values of 9.0 × 1015 h-1 M⊙ and 31 keV in ΛCDM, to the highest values of 20.9 × 1015h-1M⊙, 65 keV in SCDM. As compared with the largest virialized object seen in the universe, the richest clusters of galaxies, we can safely rule out the OCDM model. In addition, the SCDM model is very unlikely because of the unreasonably high virial mass and temperature. Our computation favors the prevailing ΛCDM model in which superclusters may be marginally regarded as dynamically-virialized systems.

Beyond the Schwarzschild Metric

2018 ◽  
Author(s):  
David M. Wittman
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Gravitational Waves ◽  
Test Particle ◽  
Direct Detection ◽  
Relativistic Effects ◽  
Big Bang ◽  
Clusters Of Galaxies ◽  
General Relativistic ◽  
The Universe

General relativity explains much more than the spacetime around static spherical masses.We briefly assess general relativity in the larger context of physical theories, then explore various general relativistic effects that have no Newtonian analog. First, source massmotion gives rise to gravitomagnetic effects on test particles.These effects also depend on the velocity of the test particle, which has substantial implications for orbits around black holes to be further explored in Chapter 20. Second, any changes in the sourcemass ripple outward as gravitational waves, and we tell the century‐long story from the prediction of gravitational waves to their first direct detection in 2015. Third, the deflection of light by galaxies and clusters of galaxies allows us to map the amount and distribution of mass in the universe in astonishing detail. Finally, general relativity enables modeling the universe as a whole, and we explore the resulting Big Bang cosmology.

Magnetic Field Evolution in Merging Clusters of Galaxies

1999 ◽  
Vol 518 (2) ◽  
pp. 594-602 ◽  
Author(s):  
Kurt Roettiger ◽  
James M. Stone ◽  
Jack O. Burns
Keyword(s):  
Magnetic Field ◽  
Clusters Of Galaxies ◽  
Field Evolution

scholarly journals Constraining the Swiss-Cheese IR-Fixed Point Cosmology with Cosmic Expansion

Universe ◽  
2021 ◽  
Vol 7 (8) ◽  
pp. 263
Author(s):  
Ayan Mitra ◽  
Vasilios Zarikas ◽  
Alfio Bonanno ◽  
Michael Good ◽  
Ertan Güdekli
Keyword(s):  
Fixed Point ◽  
Cosmological Constant ◽  
Cosmic Acceleration ◽  
Fine Tuning ◽  
Clusters Of Galaxies ◽  
Swiss Cheese ◽  
Coincidence Problem ◽  
Cosmological Expansion ◽  
Cosmic Evolution ◽  
Previous Assumption

A recent work proposed that the recent cosmic passage to a cosmic acceleration era is the result of the existence of small anti-gravity sources in each galaxy and clusters of galaxies. In particular, a Swiss-cheese cosmology model, which relativistically integrates the contribution of all these anti-gravity sources on a galactic scale has been constructed assuming the presence of an infrared fixed point for a scale dependent cosmological constant. The derived cosmological expansion provides an explanation for both the fine tuning and the coincidence problem. The present work relaxes the previous assumption on the running of the cosmological constant and allows for a generic scaling around the infrared fixed point. Our analysis reveals that, in order to produce a cosmic evolution consistent with the best ΛCDM model, the IR-running of the cosmological constant is consistent with the presence of an IR-fixed point.

scholarly journals NIHAO – XXV. Convergence in the cusp-core transformation of cold dark matter haloes at high star formation thresholds

2020 ◽  
Vol 499 (2) ◽  
pp. 2648-2661
Author(s):  
Aaron A Dutton ◽  
Tobias Buck ◽  
Andrea V Macciò ◽  
Keri L Dixon ◽  
Marvin Blank ◽  
...  
Keyword(s):  
Dark Matter ◽  
Star Formation ◽  
Galaxy Formation ◽  
Cold Dark Matter ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Good Description ◽  
Good Match ◽  
Virial Mass ◽  
Density Threshold

ABSTRACT We use cosmological hydrodynamical galaxy formation simulations from the NIHAO project to investigate the response of cold dark matter (CDM) haloes to baryonic processes. Previous work has shown that the halo response is primarily a function of the ratio between galaxy stellar mass and total virial mass, and the density threshold above which gas is eligible to form stars, n[cm−3]. At low n all simulations in the literature agree that dwarf galaxy haloes are cuspy, but at high n ≳ 100 there is no consensus. We trace halo contraction in dwarf galaxies with n ≳ 100 reported in some previous simulations to insufficient spatial resolution. Provided the adopted star formation threshold is appropriate for the resolution of the simulation, we show that the halo response is remarkably stable for n ≳ 5, up to the highest star formation threshold that we test, n = 500. This free parameter can be calibrated using the observed clustering of young stars. Simulations with low thresholds n ≤ 1 predict clustering that is too weak, while simulations with high star formation thresholds n ≳ 5, are consistent with the observed clustering. Finally, we test the CDM predictions against the circular velocities of nearby dwarf galaxies. Low thresholds predict velocities that are too high, while simulations with n ∼ 10 provide a good match to the observations. We thus conclude that the CDM model provides a good description of the structure of galaxies on kpc scales provided the effects of baryons are properly captured.

Sign in / Sign up

Export Citation Format

Share Document