scholarly journals Cosmological searches for a noncold dark matter component

2017 ◽  
Vol 96 (4) ◽  
Author(s):  
Stefano Gariazzo ◽  
Miguel Escudero ◽  
Roberta Diamanti ◽  
Olga Mena
Keyword(s):  
Dark Matter ◽  
Matter Component

scholarly journals Two natural scenarios for dark matter particles coexisting with supersymmetry

2019 ◽  
Vol 34 (02) ◽  
pp. 1930001 ◽  
Author(s):  
Maxwell Throm ◽  
Reagan Thornberry ◽  
John Killough ◽  
Brian Sun ◽  
Gentill Abdulla ◽  
...  
Keyword(s):  
Dark Matter ◽  
Cross Sections ◽  
Higgs Sector ◽  
Weakly Interacting Massive Particles ◽  
Indirect Detection ◽  
Experimental Facilities ◽  
Direct And Indirect Detection ◽  
Extended Higgs Sector ◽  
Matter Component ◽  
Multicomponent Model

We describe two natural scenarios in which both dark matter, weakly interacting massive particles (WIMPs) and a variety of supersymmetric partners should be discovered in the foreseeable future. In the first scenario, the WIMPs are neutralinos, but they are only one component of the dark matter, which is dominantly composed of other relic particles such as axions. (This is the multicomponent model of Baer, Barger, Sengupta and Tata.) In the second scenario, the WIMPs result from an extended Higgs sector and may be the only dark matter component. In either scenario, both the dark matter WIMP and a plethora of other neutral and charged particles await discovery at many experimental facilities. The new particles in the second scenario have far weaker cross-sections for direct and indirect detection via their gauge interactions, which are either momentum-dependent or second-order. However, as we point out here, they should have much stronger interactions via the Higgs. We estimate that their interactions with fermions will then be comparable to (although not equal to) those of neutralinos with a corresponding Higgs interaction. It follows that these newly proposed dark matter particles should be within the reach of emerging and proposed facilities for direct, indirect and collider-based detection.

scholarly journals The Search for Dark Matter in Draco and Ursa Minor: A Three Year Progress Report

1987 ◽  
Vol 117 ◽  
pp. 153-160 ◽  
Author(s):  
M. Aaronson ◽  
E. Olszewski
Keyword(s):  
Dark Matter ◽  
Velocity Dispersion ◽  
Progress Report ◽  
Radial Velocities ◽  
Circumstantial Evidence ◽  
Dwarf Spheroidal Galaxies ◽  
Ursa Minor ◽  
Stellar Velocity ◽  
Atmospheric Motions ◽  
Matter Component

We report the cumulative results of an on-going effort to measure the stellar velocity dispersion in two nearby dwarf spheroidal galaxies. Radial velocities having an accuracy ≲ 2 km s−1 have now been secured for ten stars in Ursa Minor and eleven stars in Draco (including 16 K giants and 5 C types). Most objects have been observed at two or more epochs. Stars having non-variable velocities yield in both dwarfs a large (∼ 10 km s−1) dispersion. These results cannot be explained by atmospheric motions, and circumstantial evidence suggests that the effects of undetected binaries are also not likely to be important. Instead, it seems that both spheroidals contain a substantial dark matter component, which therefore must be “cold” in form.

scholarly journals Evidence for Light-weight Local Group Dwarf Spheroidal Galaxies

2004 ◽  
Vol 220 ◽  
pp. 365-366
Author(s):  
J. R. Kuhn ◽  
D. Kocevski
Keyword(s):  
Dark Matter ◽  
Milky Way ◽  
Local Group ◽  
Light Weight ◽  
Natural Explanation ◽  
Dwarf Spheroidal Galaxies ◽  
Ursa Minor ◽  
Matter Component ◽  
Morphological State ◽  
Spheroidal Galaxies

A simple and natural explanation for the dynamics and morphology of the Local Group Dwarf Spheroidal galaxies, Draco (Dra) and Ursa Minor (UMi), is that they are weakly unbound stellar systems with no significant dark matter component. A gentle, but persistent, Milky Way (MW) tide has left them in their current kinematic and morphological state (the “parametric tidal excitation”). A new test of a dark matter dominated dS potential follows from a careful observation of the “clumpiness” of the dS stellar surface density.

scholarly journals Dark Matter

2011 ◽  
Vol 20 (2) ◽  
Author(s):  
J. Einasto
Keyword(s):  
Dark Matter ◽  
Elementary Particles ◽  
A Minor ◽  
The Universe ◽  
Matter Component

AbstractI give a review of the development of the concept of dark matter. The dark matter story passed through several stages from a minor observational puzzle to a major challenge for theory of elementary particles. Modern data suggest that dark matter is the dominant matter component in the Universe, and that it consists of some unknown non-baryonic particles. Dark matter is the dominant matter component in the Universe, thus properties of dark matter particles determine the structure of the cosmic web.

scholarly journals DARK MATTER PREDICTION FROM CANONICAL QUANTUM GRAVITY WITH FRAME FIXING

2004 ◽  
Vol 19 (37) ◽  
pp. 2777-2784 ◽  
Author(s):  
GIOVANNI CORVINO ◽  
GIOVANNI MONTANI
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Dark Matter Candidate ◽  
New Energy ◽  
Frw Model ◽  
Canonical Quantum Gravity ◽  
The Universe ◽  
Matter Component ◽  
Canonical Quantum ◽  
Relativistic Matter

We show how, in canonical quantum cosmology, the frame fixing induces a new energy density contribution having features compatible with the (actual) cold dark matter component of the Universe. First we quantize the closed Friedmann–Robertson–Walker (FRW) model in a synchronous reference and determine the spectrum of the super-Hamiltonian in the presence of ultra-relativistic matter and a perfect gas contribution. Then we include in this model small inhomogeneous (spherical) perturbations in the spirit of the Lemaitre–Tolman cosmology. The main issue of our analysis consists in outlining that, in the classical limit, the nonzero eigenvalue of the super-Hamiltonian can account for the present value of the dark matter critical parameter. Furthermore we obtain a direct correlation between the inhomogeneities in our dark matter candidate and those that appear in the ultra-relativistic matter.

scholarly journals Cosmological baryon transfer in the simba simulations

2019 ◽  
Vol 491 (4) ◽  
pp. 6102-6119 ◽  
Author(s):  
Josh Borrow ◽  
Daniel Anglés-Alcázar ◽  
Romeel Davé
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Large Scale ◽  
Initial Conditions ◽  
Mass Range ◽  
Gas Content ◽  
Final State ◽  
Cosmological Simulations ◽  
Baryon Transfer ◽  
Matter Component

ABSTRACT We present a framework for characterizing the large-scale movement of baryons relative to dark matter in cosmological simulations, requiring only the initial conditions and final state of the simulation. This is performed using the spread metric that quantifies the distance in the final conditions between initially neighbouring particles, and by analysing the baryonic content of final haloes relative to that of the initial Lagrangian regions (LRs) defined by their dark matter component. Applying this framework to the simba cosmological simulations, we show that 40 per cent (10 per cent) of cosmological baryons have moved $\gt 1\, h^{-1}\, {\rm Mpc}{}$ ($3\, h^{-1}\, {\rm Mpc}{}$) by z = 0, primarily due to entrainment of gas by jets powered by an active galactic nucleus, with baryons moving up to $12\, h^{-1}\, {\rm Mpc}{}$ away in extreme cases. Baryons decouple from the dynamics of the dark matter component due to hydrodynamic forces, radiative cooling, and feedback processes. As a result, only 60 per cent of the gas content in a given halo at z = 0 originates from its LR, roughly independent of halo mass. A typical halo in the mass range Mvir = 1012–1013 M⊙ only retains 20 per cent of the gas originally contained in its LR. We show that up to 20 per cent of the gas content in a typical Milky Way-mass halo may originate in the region defined by the dark matter of another halo. This inter-Lagrangian baryon transfer may have important implications for the origin of gas and metals in the circumgalactic medium of galaxies, as well as for semi-analytic models of galaxy formation and ‘zoom-in’ simulations.

scholarly journals MODIFIED AVERAGING PROCESSES IN COSMOLOGY AND THE STRUCTURED FRW MODEL

2009 ◽  
Vol 18 (07) ◽  
pp. 1177-1192 ◽  
Author(s):  
SHAHRAM KHOSRAVI ◽  
REZA MANSOURI ◽  
EHSAN KOURKCHI
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Volume Averaging ◽  
Matter Density ◽  
Singular Behavior ◽  
Gauge Dependence ◽  
Frw Model ◽  
Matter Component ◽  
Ltb Metric

We study the volume averaging of inhomogeneous metrics within GR and discuss its shortcomings, such as gauge dependence, singular behavior as a result of caustics, and causality violations. To remedy these shortcomings, we suggest some modifications to this method. As a case study we focus on the inhomogeneous structured FRW model based on a flat LTB metric. The effect of averaging is then studied in terms of an effective backreaction fluid. It is shown that, contrary to the claims in the literature, the backreaction fluid behaves like a dark matter component, instead of dark energy, having a density of the order of 10-5 times the matter density, and, most importantly, it is gauge-dependent.

scholarly journals H I Imaging Surveys: Gas and Galaxy Evolution in Different Environments

2010 ◽  
Vol 6 (S277) ◽  
pp. 41-46
Author(s):  
Jacqueline van Gorkom
Keyword(s):  
Dark Matter ◽  
Star Formation ◽  
Galaxy Evolution ◽  
Large Scale ◽  
Large Scale Structure ◽  
Local Universe ◽  
Formation And Evolution ◽  
Gas Accretion ◽  
Optical Surveys ◽  
Matter Component

AbstractOur understanding of the formation and evolution of galaxies and the large scale structure has advanced enormously over the last decade, thanks to an impressive synergy between theoretical and observational efforts. While the growth of the dark matter component seems well understood, the physics of the gas, during its accretion, removal and/or depletion is less well understood. Increasingly large scale optical surveys are tracing out the cosmic web of filaments and voids and mathematical tools have been developed to describe these structures and identify galaxies in specific environments. H I imaging surveys begin to answer the question: how do galaxies get and lose their gas. The best evidence for ongoing gas accretion is found in the lowest density environments, while removal of gas in the highest density environments stops star formation and reddens the galaxies. Although current H I emission surveys are limited to redshifts less than 0.2, this is where the LSS is best defined and much can be learned in the local universe.

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