Dark matter halo with charge in pseudo-spheroidal geometry

2021 ◽  
pp. 2150178
Author(s):  
Mithun Ghosh
Keyword(s):  
Dark Matter ◽  
Equation Of State ◽  
Perfect Fluid ◽  
Circular Orbit ◽  
Galactic Halo ◽  
Rotational Velocity ◽  
Dark Matter Halo ◽  
Cosmological Observations ◽  
The Stability ◽  
Spheroidal Geometry

The concept of dark matter (DM) hypothesis comes out as a result from the input of the observed flat rotational velocity. With the assumption that the galactic halo is pseudo-spheroidal and filled with charged perfect fluid, we have obtained a solution which has inkling to a (nearly) flat universe, compatible with the modern day cosmological observations. Various other important aspects of the solution such as attractive gravity in the halo region and the stability of the circular orbit are also explored. Also, the matter in the halo region satisfies the known equation of state which indicates its non-exotic nature.

Charged perfect fluid dark matter model: Known mass density function approach

2021 ◽  
Vol 36 (07) ◽  
pp. 2150043
Author(s):  
Mithun Ghosh
Keyword(s):  
Dark Matter ◽  
Density Function ◽  
Perfect Fluid ◽  
Galactic Halo ◽  
Spiral Galaxies ◽  
Mass Density ◽  
Rotational Velocity ◽  
Cosmological Observations ◽  
Matter Model ◽  
Dark Matter Model

The concept of dark matter has been imported to explain the observed velocity profile of the spiral galaxies, the flat rotational velocity. Taking the flatness of rotation curves as an input and assuming that the galactic halo is filled with charged perfect fluid having known mass density function, we obtain a space time metric in the galactic halo region. The acquired solution indicates to a (nearly) flat universe, consistent with the present day cosmological observations. Various other aspects of the solution such as attractive gravity in the halo region, stability of the circular orbit, etc., are also analyzed.

scholarly journals Observational Role of Dark Matter in f(R) Models for Structure Formation

2018 ◽  
Vol 46 ◽  
pp. 1860045
Author(s):  
Murli Manohar Verma ◽  
Bal Krishna Yadav
Keyword(s):  
Dynamical System ◽  
Dark Matter ◽  
Fixed Points ◽  
Gravity Models ◽  
Stability Conditions ◽  
Cosmological Observations ◽  
General Relativistic ◽  
The Stability ◽  
The Universe

The fixed points for the dynamical system in the phase space have been calculated with dark matter in the [Formula: see text] gravity models. The stability conditions of these fixed points are obtained in the ongoing accelerated phase of the universe, and the values of the Hubble parameter and Ricci scalar are obtained for various evolutionary stages of the universe. We present a range of some modifications of general relativistic action consistent with the [Formula: see text]CDM model. We elaborate upon the fact that the upcoming cosmological observations would further constrain the bounds on the possible forms of [Formula: see text] with greater precision that could in turn constrain the search for dark matter in colliders.

Rotation Curve and Dark Matter Halo profile in Finsler Geometry

2020 ◽  
Author(s):  
Nupur Paul ◽  
Farook Rahaman ◽  
Nasarul Islam ◽  
S.S. De
Keyword(s):  
Dark Matter ◽  
Rotational Velocity ◽  
Finsler Geometry ◽  
Outer Region ◽  
Recent Time ◽  
Dark Matter Halo ◽  
Dark Matter Halos ◽  
Radial Profiles ◽  
Galactic Dark Matter ◽  
Specific Equation

Galactic dark matter is an active area of research in recent time. Several researchers proposed several descriptions of radial profiles of dark matter halos by using N-body simulations. Among them, Navarro, Frenk and White (NFW) dark matter profile provides the most accurate description of dark matter halos. It is believed that dark matter is smooth and distributed uniformly throughout space. Using Finslerian geometrical background and a specific equation of state, we propose a new way to estimate the rotational velocity of galaxies based on the NFW dark matter profile. On small scales the first few distances (about 30 kpc) the velocity increases whereas in the outer region of the galaxies, the rotational velocity is found to be more or less constant which supports observed rotational velocities.

scholarly journals SOME PROPERTIES OF THE "STRING GAS" WITH THE EQUATION OF STATE $p = -\frac{1}{3} \rho$

2012 ◽  
Vol 21 (01) ◽  
pp. 1250004 ◽  
Author(s):  
ALEXANDER YU. KAMENSHCHIK ◽  
ISAAK M. KHALATNIKOV
Keyword(s):  
Dark Matter ◽  
Equation Of State ◽  
Perfect Fluid ◽  
Spherically Symmetric ◽  
Rotation Curves ◽  
Matter Effects ◽  
Symmetric Spacetimes ◽  
State Formula ◽  
Spherically Symmetric Spacetimes

We show that the string gas — a perfect fluid with the equation of state [Formula: see text] possesses rather interesting properties. In Friedmann universes its presence can change the observable topology of the space; in the spherically symmetric spacetimes it produces rather bizzare geometries and in a way its influence on the rotation curves mimics the dark matter effects.

scholarly journals Hot gas in Milky Way size galaxies at z=0

2016 ◽  
Vol 11 (S321) ◽  
pp. 72-74
Author(s):  
Santi Roca-Fàbrega ◽  
Pedro Colin ◽  
Octavio Valenzuela ◽  
Francesca Figueras ◽  
Yair Krongold
Keyword(s):  
Dark Matter ◽  
Column Density ◽  
Milky Way ◽  
Galactic Halo ◽  
Careful Analysis ◽  
Dark Matter Halo ◽  
Hot Gas ◽  
Satellite Galaxy ◽  
Real Distribution ◽  
Axisymmetric Structures

AbstractWe present a new set of cosmological Milky Way size galaxy simulations using ART. In our simulations the main system has been evolved inside a 28 Mpc cosmological box with a spatial resolution of 109 pc. At z=0 our systems have an Mvir = 6 − 8 × 1011 M⊙. In several of out models we have observed how a well defined disk is formed inside the dark matter halo and the overall amount of gas and stars is comparable with MW observations. Several non-axisymmetric structures arise out of the disk: spirals, bars and also a warp. We have also observed that a huge reservoir of hot gas is present at large distances from the disk, embedded in the dark matter halo region, accounting for only a fraction of the ”missing baryons”. Gas column density, emission (EM) and dispersion (DM) measure have been computed from inside the simulated disk at a position of 8 kpc from the center and in several directions. Our preliminary results reveal that the distribution of hot gas is non-isotropic according with observations (Gupta et al. 2012, Gupta et al. 2014). Also its metallic content presents a clear bimodality what is a consequence of a recent accretion of a satellite galaxy among others. After a careful analysis we confirm that due to the anisotropy in the gas distribution a new observational parameter needs to be defined to recover the real distribution of hot gas in the galactic halo (Roca-Fàbrega et al. 2016).

scholarly journals Revealing the Network of Periodic Orbits in Galaxy Models with a Prolate or an Oblate Dark Matter Halo Component

2016 ◽  
Vol 25 (2) ◽  
Author(s):  
Euaggelos E. Zotos
Keyword(s):  
Dark Matter ◽  
Periodic Orbits ◽  
Dark Matter Halo ◽  
Meridional Plane ◽  
Stability Of Periodic Orbits ◽  
The Stability

AbstractLocating the position of periodic orbits in galaxies is undoubtedly an issue of paramount importance. We reveal the position and the stability of periodic orbits of stars moving in the meridional plane (

scholarly journals Bounce universe induced by an inhomogeneous dark fluid coupled with dark matter

2014 ◽  
Vol 29 (15) ◽  
pp. 1450078 ◽  
Author(s):  
I. Brevik ◽  
V. V. Obukhov ◽  
A. V. Timoshkin
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Equation Of State ◽  
Power Law ◽  
Time Dependent ◽  
Late Time ◽  
Exponential Form ◽  
Small Perturbations ◽  
Double Exponential ◽  
The Stability

We investigate cosmological models with a linear inhomogeneous time-dependent equation-of-state (EoS) for the dark energy, coupled with dark matter, leading to a bounce cosmology. Equivalent descriptions in terms of the EoS parameters for an exponential, a power-law, or a double exponential form of the scale factor a is obtained. The stability of the solutions is explored, by considering small perturbations around the critical points for the bounce in the early and in the late-time universe.

scholarly journals ON THIN-SHELL WORMHOLES EVOLVING IN FLAT FRW SPACETIMES

2011 ◽  
Vol 26 (12) ◽  
pp. 857-863 ◽  
Author(s):  
M. LA CAMERA
Keyword(s):  
Stability Analysis ◽  
Equation Of State ◽  
Perfect Fluid ◽  
Dynamic Systems ◽  
Spherical Symmetry ◽  
Thin Shell ◽  
Time Dependent ◽  
State Formula ◽  
Thin Shell Wormholes ◽  
The Stability

We analyze the stability of a class of thin-shell wormholes with spherical symmetry evolving in flat FRW spacetimes. The wormholes considered here are supported at the throat by a perfect fluid with equation of state [Formula: see text] and have a physical radius equal to aR, where a is a time-dependent function describing the dynamics of the throat and R is the background scale factor. The study of wormhole stability is done by means of the stability analysis of dynamic systems.

DARK ENERGY AND DARK MATTER FROM COSMOLOGICAL OBSERVATIONS

2006 ◽  
Vol 21 (08n09) ◽  
pp. 1938-1949 ◽  
Author(s):  
STEEN HANNESTAD
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Equation Of State ◽  
Physical Properties ◽  
Speed Of Sound ◽  
Present Status ◽  
Cosmological Observations ◽  
Review Current ◽  
Effective Speed

The present status of our knowledge about the dark matter and dark energy is reviewed. Particular emphasis is put on the bounds on the content of cold and hot dark matter from cosmological observations are discussed in some detail. I also review current bounds on the physical properties of dark energy, mainly its equation of state and effective speed of sound.

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