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An important consequence which comes from noncommutativity (NC) is undoubtedly the energy density characterized by a microscopic free parameter; indeed a Trans-Planckian parameter. However, its functional form is an interesting and useful…

General Relativity and Quantum Cosmology · Physics 2017-08-08 Miguel A. Garcia-Aspeitia , J. C. Lopez-Dominguez , C. Ortiz , Sinhue Hinojosa-Ruiz , Mario A. Rodriguez-Meza

We demonstrate a general relativistic approach to model dark matter halos using the Einstein cluster, with the matter stress-energy generated by collisionless particles moving on circular geodesics in all possible angular directions and…

General Relativity and Quantum Cosmology · Physics 2025-05-23 Ritwik Acharyya , Pritam Banerjee , Sayan Kar

We investigate the non-gaussian properties of cosmic-string-seeded linear density perturbations with cold and hot dark matter backgrounds, using high-resolution numerical simulations. We compute the one-point probability density function of…

Astrophysics · Physics 2009-10-30 P. P. Avelino , E. P. S. Shellard , J. H. P. Wu , B. Allen

Stellar and gas kinematics of galaxies are a sensitive probe of the dark matter distribution in the halo. The popular fuzzy dark matter models predict the peculiar shape of density distribution in galaxies: specific dense core with sharp…

Cosmology and Nongalactic Astrophysics · Physics 2023-06-07 Mariia Khelashvili , Anton Rudakovskyi , Sabine Hossenfelder

Nuclear Star Clusters (NSCs) are dense clusters of stars that reside in the centers of a majority of the galaxies. In this paper, we study the density profiles for 29 galaxies in a volume-limited survey within 10 Mpc to characterize their…

Astrophysics of Galaxies · Physics 2020-09-09 Renuka Pechetti , Anil Seth , Nadine Neumayer , Iskren Georgiev , Nikolay Kacharov , Mark den Brok

Density profiles of simulated galaxy cluster-sized dark matter haloes are analysed in the context of a recently introduced nonextensive theory of dark matter and gas density distributions. Nonextensive statistics accounts for long-range…

Astrophysics · Physics 2009-11-11 T. Kronberger , M. P. Leubner , E. van Kampen

Given the dimensions (including thickness) of a galaxy, and its rotation profile, a method is shown that finds the mass and density distributions in the defined envelope that will cause that rotation profile with near-exact speed matches.…

Astrophysics · Physics 2007-05-23 Kenneth F. Nicholson

In this paper a new theory of Dark Matter is proposed. Experimental analysis of several Galaxies show how the non-gravitational contribution to galactic Velocity Rotation Curves can be interpreted as that due to the Cosmological Constant…

Astrophysics · Physics 2007-05-23 G. V. Kraniotis , S. B. Whitehouse

Noncommutativity is an idea dating back to the early times of Quantum Mechanics and that string theory induced noncommutative (NC) geometry which provides an effective framework to study short distance spacetime dynamics. Also, string…

General Relativity and Quantum Cosmology · Physics 2018-08-02 Dharm Veer Singh , Md Sabir Ali , Sushant G. Ghosh

We present a simple model for the shape of the distribution function of galaxy peculiar velocities. We show how both nonlinear and linear theory terms combine to produce a distribution which has an approximately Gaussian core with…

Astrophysics · Physics 2009-10-31 Ravi K. Sheth , Antonaldo Diaferio

We study a Newtonian cosmological model in the context of a noncommutative space. It is shown that the trajectories of a test particle undergo modifications such that it no longer satisfies the cosmological principle. For the case of a…

High Energy Physics - Theory · Physics 2010-11-05 Juan M. Romero , J. A. Santiago

We study a classical, noncommutative (NC), Friedmann-Robertson-Walker cosmological model. The spatial sections may have positive, negative or zero constant curvatures. The matter content is a generic perfect fluid. The initial…

General Relativity and Quantum Cosmology · Physics 2016-02-12 G. A. Monerat , E. V. Corrêa Silva , C. Neves , G. Oliveira-Neto , L. G. Rezende Rodrigues , M. Silva de Oliveira

We investigate the properties of clusters of galaxies in two cosmological models using N-body simulations and the Press-Schecter (PS) theory. In the first model, the initial power spectrum of density fluctuations is in the form P(k) \propto…

Astrophysics · Physics 2009-10-30 Ivan Suhhonenko , Mirt Gramann

This paper discusses a new model for galactic dark matter by combining an anisotropic pressure field corresponding to normal matter and a quintessence dark energy field having a characteristic parameter $\omega_q$ such that $-1<\omega_q<…

General Relativity and Quantum Cosmology · Physics 2011-07-15 F. Rahaman , Peter K. F. Kuhfittig , K. Chakraborty , M. Kalam , D. Hossain

(Abridged) The analysis of the rotation curves (RCs) of spiral galaxies provides an efficient diagnostic for studying the properties of dark matter halos and their relations with the baryonic material. We have modeled the RCs of galaxies…

Cosmology and Nongalactic Astrophysics · Physics 2011-09-21 Laurent Chemin , W. J. G. de Blok , Gary A. Mamon

Non-circular (NC) motions represent the imprints of non-axisymmetric structures in galaxies, providing opportunities to study the physical properties of gas departing from circular rotation. In this work, we have conducted a systematic…

Astrophysics of Galaxies · Physics 2024-10-31 Carlos Lopez-Coba , Lihwai Lin , Justus Neumann , Matthew A. Bershady

We show the existence of a time-space noncommutativity (NC) for the physical system of a massive relativistic particle by exploiting the underlying symmetry properties of this system. The space-space NC is eliminated by the consideration of…

High Energy Physics - Theory · Physics 2007-05-23 R. P. Malik

This paper discusses the observed at rotation curves of galaxies in the context of noncommutative geometry. The energy density of such a geometry is diffused throughout a region due to the uncertainty encoded in the coordinate commutator.…

General Relativity and Quantum Cosmology · Physics 2016-11-25 F. Rahaman , Peter K. F. Kuhfittig , K. Chakraborty , A. A. Usmani , Saibal Ray

We find classical solutions of two dimensional noncritical string theory which give rise to geometries with spacelike boundaries, similar to spacetimes with cosmological event horizons. In the c=1 matrix model, these solutions have a…

High Energy Physics - Theory · Physics 2009-11-10 Sumit R. Das , Joanna L. Karczmarek

Considering galaxies as self - gravitating systems of many collisionless particles allows to use methods of statistical mechanics inferring the distribution function of these stellar systems. Actually, the long range nature of the…

Cosmology and Nongalactic Astrophysics · Physics 2014-02-04 V. F. Cardone , M. P. Leubner , A. Del Popolo
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