scholarly journals A tight scaling relation of dark matter in galaxy clusters

2014 ◽  
Vol 442 (1) ◽  
pp. L14-L17 ◽  
Author(s):  
Man Ho Chan
Keyword(s):  
Dark Matter ◽  
Galaxy Clusters ◽  
Scaling Relation

scholarly journals Understanding the large inferred Einstein radii of observed low-mass galaxy clusters

2020 ◽  
Vol 494 (4) ◽  
pp. 4706-4712 ◽  
Author(s):  
Andrew Robertson ◽  
Richard Massey ◽  
Vincent Eke
Keyword(s):  
Dark Matter ◽  
Galaxy Clusters ◽  
Gravitational Lensing ◽  
Cold Dark Matter ◽  
Baryonic Matter ◽  
Analysis Method ◽  
Critical Curves ◽  
Hydrodynamical Simulation ◽  
Low Mass ◽  
Main Effects

ABSTRACT We assess a claim that observed galaxy clusters with mass ${\sim}10^{14} \mathrm{\, M_\odot }$ are more centrally concentrated than predicted in lambda cold dark matter (ΛCDM). We generate mock strong gravitational lensing observations, taking the lenses from a cosmological hydrodynamical simulation, and analyse them in the same way as the real Universe. The observed and simulated lensing arcs are consistent with one another, with three main effects responsible for the previously claimed inconsistency. First, galaxy clusters containing baryonic matter have higher central densities than their counterparts simulated with only dark matter. Secondly, a sample of clusters selected because of the presence of pronounced gravitational lensing arcs preferentially finds centrally concentrated clusters with large Einstein radii. Thirdly, lensed arcs are usually straighter than critical curves, and the chosen image analysis method (fitting circles through the arcs) overestimates the Einstein radii. After accounting for these three effects, ΛCDM predicts that galaxy clusters should produce giant lensing arcs that match those in the observed Universe.

scholarly journals Annihilating dark matter search with 12 yr of Fermi LAT data in nearby galaxy clusters

2021 ◽  
Vol 502 (3) ◽  
pp. 4039-4047
Author(s):  
Charles Thorpe-Morgan ◽  
Denys Malyshev ◽  
Christoph-Alexander Stegen ◽  
Andrea Santangelo ◽  
Josef Jochum
Keyword(s):  
Dark Matter ◽  
Galaxy Clusters ◽  
Gamma Ray ◽  
Nearby Galaxy ◽  
Galactic Latitude ◽  
Dark Matter Search ◽  
Dwarf Spheroidal Galaxies ◽  
Characteristic Signal ◽  
Small Factor ◽  
The Impact

ABSTRACT Galaxy clusters are the largest virialized objects in the Universe and, as such, have high dark matter (DM) concentrations. This abundance of dark matter makes them promising targets for indirect DM searches. Here we report the details of a search, utilizing almost 12 yr of Fermi/LAT data, for gamma-ray signatures from the pair annihilation of WIMP dark matter in the GeV energy band. From this, we present the constraints on the annihilation cross-section for the $b\overline{b}$, W+W−, and γγ channels, derived from the non-detection of a characteristic signal from five nearby, high Galactic latitude, galaxy clusters (Centaurus, Coma, Virgo, Perseus, and Fornax). We discuss the potential of a boost to the signal due to the presence of substructures in the DM haloes of selected objects, as well as the impact of uncertainties in DM profiles on the presented results. We assert that the obtained limits are, within a small factor, comparable to the best available limits of those based on Fermi/LAT observations of dwarf spheroidal galaxies.

scholarly journals Turnaround radius of galaxy clusters in N-body simulations

2020 ◽  
Vol 639 ◽  
pp. A122 ◽  
Author(s):  
Giorgos Korkidis ◽  
Vasiliki Pavlidou ◽  
Konstantinos Tassis ◽  
Evangelia Ntormousi ◽  
Theodore N. Tomaras ◽  
...  
Keyword(s):  
Dark Matter ◽  
Galaxy Clusters ◽  
Cosmological Parameters ◽  
Three Dimensional ◽  
Average Density ◽  
Matter Density ◽  
Tidal Forces ◽  
Spherical Collapse ◽  
Collapse Model ◽  
Model C

Aims. We use N-body simulations to examine whether a characteristic turnaround radius, as predicted from the spherical collapse model in a ΛCDM Universe, can be meaningfully identified for galaxy clusters in the presence of full three-dimensional effects. Methods. We use The Dark Sky Simulations and Illustris-TNG dark-matter-only cosmological runs to calculate radial velocity profiles around collapsed structures, extending out to many times the virial radius R200. There, the turnaround radius can be unambiguously identified as the largest nonexpanding scale around a center of gravity. Results. We find that: (a) a single turnaround scale can meaningfully describe strongly nonspherical structures. (b) For halos of masses M200 >  1013 M⊙, the turnaround radius Rta scales with the enclosed mass Mta as Mta1/3, as predicted by the spherical collapse model. (c) The deviation of Rta in simulated halos from the spherical collapse model prediction is relatively insensitive to halo asphericity. Rather, it is sensitive to the tidal forces due to massive neighbors when these are present. (d) Halos exhibit a characteristic average density within the turnaround scale. This characteristic density is dependent on cosmology and redshift. For the present cosmic epoch and for concordance cosmological parameters (Ωm ∼ 0.3; ΩΛ ∼ 0.7) turnaround structures exhibit a density contrast with the matter density of the background Universe of δ ∼ 11. Thus, Rta is equivalent to R11 – in a way that is analogous to defining the “virial” radius as R200 – with the advantage that R11 is shown in this work to correspond to a kinematically relevant scale in N-body simulations.

scholarly journals A Search for Neutrinos from Decaying Dark Matter in Galaxy Clusters and Galaxies with IceCube

2021 ◽  
Author(s):  
Minjin Jeong ◽  
Rasha Abbasi ◽  
Markus Ackermann ◽  
Jenni Adams ◽  
Juanan Aguilar ◽  
...  
Keyword(s):  
Dark Matter ◽  
Galaxy Clusters ◽  
Decaying Dark Matter

scholarly journals Observing Galaxy Clusters with eROSITA: Simulations

10.14311/1466 ◽  
2011 ◽  
Vol 51 (6) ◽  
Author(s):  
J. Hölzl ◽  
J. Wilms ◽  
I. Kreykenbohm ◽  
Ch. Schmid ◽  
Ch. Grossberger ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Dark Matter ◽  
Dark Energy ◽  
Galaxy Clusters ◽  
Cosmological Parameters ◽  
Mass Function ◽  
Angular Diameter ◽  
Monte Carlo Code ◽  
X Rays ◽  
Sky Survey

The eROSITA instrument on board the Russian Spectrum Roentgen Gamma spacecraft, which will be launched in 2013,will conduct an all sky survey in X-rays. A main objective of the survey is to observe galaxy clusters in order to constrain cosmological parameters and to obtain further knowledge about dark matter and dark energy. For the simulation of the eROSITA survey we present a Monte-Carlo code generating a mock catalogue of galaxy clusters distributed accordingto the mass function of [1]. The simulation generates the celestial coordinates as well as the cluster mass and redshift. From these parameters, the observed intensity and angular diameter are derived. These are used to scale Chandra cluster images as input for the survey-simulation.

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

Most of the Universe is Missing!

2019 ◽  
pp. 64-72
Author(s):  
Nicholas Mee
Keyword(s):  
Dark Matter ◽  
Galaxy Clusters ◽  
Early Universe ◽  
The World ◽  
Unknown Form ◽  
Theory Of Gravity ◽  
Stable Particles ◽  
The Universe

Most of the matter in the universe exists in an unknown form called dark matter. All estimates of the mass of galaxies and galaxy clusters suggest they contain far more matter than is visible to us in the form of stars. Conventional explanations, such as the existence of large quantities of burnt-out stars known as MACHOs or dark gas clouds, have been ruled out. The most popular explanation is that dark matter consists of vast quantities of hypothetical stable particles known as WIMPs that were produced in vast quantities in the very early universe. Many laboratories around the world are searching for signs of these particles. These include the Italian Gran Sasso laboratory running the XENON100 experiment. Some theorists have suggested the evidence for dark matter would disappear if we had a better theory of gravity. Analysis of the Bullet Cluster indicates such proposals will not work.

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