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We consider strings with the Nambu action as extremal surfaces in a given space-time, thus, we ignore their back reaction. Especially, we look for strings sharing one symmetry with the underlying space-time. If this is a non-null symmetry,…

General Relativity and Quantum Cosmology · Physics 2007-05-23 H. -J. Schmidt , U. Semmelmann

The simplest gauge gravitation theory in Riemann-Cartan space-time leading to the solution of the problem of cosmological singularity and dark energy problem is investigated with purpose to solve the dark matter problem. It is shown that…

General Relativity and Quantum Cosmology · Physics 2017-05-09 A. V. Minkevich

We calculate predictions from wide class of `active' models of cosmic structure formation which allows us to scan the space of possible defect models. We calculate the linear cold dark matter power spectrum and Cosmic Microwave Background…

Astrophysics · Physics 2010-04-08 A. Albrecht , R. A. Battye , J. Robinson

Dark matter annihilation in Galactic substructure will produce diffuse gamma-ray emission of remarkably constant intensity across the sky, making it difficult to disentangle this Galactic dark matter signal from the extragalactic gamma-ray…

High Energy Astrophysical Phenomena · Physics 2010-04-15 Jennifer M. Siegal-Gaskins , Vasiliki Pavlidou

Our standard model of the Universe predicts the distribution of dark matter to $1\%$ at the scales needed for upcoming experiments, yet our predictions for how the luminous matter -- which has interactions besides gravity -- is distributed…

High Energy Physics - Theory · Physics 2025-03-03 Nora Elisa Chisari

Popular extensions of the standard model of particle physics feature new fields and symmetries which could, for example, dynamically generate neutrino masses from $B-L$ spontaneous symmetry breaking. If a new light scalar that decays into…

High Energy Physics - Phenomenology · Physics 2025-12-02 Guillermo Gambini , Pedro C. de Holanda , Saulo Carneiro

In the $\Lambda$-CDM paradigm, the dark halo governs the gravitational potential within which a galaxy can form and evolve. In this Letter we show that the present-day inner ($r<50\text{ kpc}$) dark halo can be significantly misaligned with…

Astrophysics of Galaxies · Physics 2023-09-18 Jiwon Jesse Han , Vadim Semenov , Charlie Conroy , Lars Hernquist

We elaborate further the $\mu$-deformation-based approach to modeling dark matter, in addition to the earlier proposed use of $\mu$-deformed thermodynamics. Herein, we construct $\mu$-deformed analogs of the Lane-Emden equation (for density…

General Physics · Physics 2020-12-03 A. M. Gavrilik , I. I. Kachurik , M. V. Khelashvili

We consider the metric perturbations around a stationary rotating Nambu-Goto string in Minkowski spacetime. By solving the linearized Einstein equations, we study the effects of azimuthal frame-dragging around the rotation axis and linear…

General Relativity and Quantum Cosmology · Physics 2009-11-06 Kouji Ogawa , Hideki Ishihara , Hiroshi Kozaki , Hiroyuki Nakano

As evidenced by a great number of works, it is common practice to assume that the Universe is flat. However, the majority of studies which make use of observational data to constrain the curvature density parameter are premised on the…

General Relativity and Quantum Cosmology · Physics 2019-07-18 Christine R. Farrugia , Joseph Sultana

The cosmological features of primordial black holes formed from collapsed cosmic string loops are studied. Observational restrictions on a population of primordial black holes are used to restrict $f$, the fraction of cosmic string loops…

High Energy Physics - Phenomenology · Physics 2008-11-26 R. R. Caldwell , E. Gates

Models for DM are invoked with various density distributions, to account for flat rotation curves of galaxies. The effect of DE on these profiles for large galaxies and clusters are also studied. The rotation curves are shown to dip at a…

Astrophysics · Physics 2007-10-25 C. Sivaram , Venkata Manohara Reddy. A

We consider a toy model to analyze the consequences of dark matter interaction with a dark energy background on the overall rotation of galaxy clusters and the misalignment between their dark matter and baryon distributions when compared to…

Cosmology and Nongalactic Astrophysics · Physics 2012-08-15 C. E. Pellicer , Elisa G. M. Ferreira , Daniel C. Guariento , André A. Costa , Leila L. Graef , Andrea Coelho , Elcio Abdalla

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

We elaborate the possibility for a deformed extra space to be considered as the dark matter candidate. To perform calculations a class of two-dimensional extra metrics was considered in the framework of the multidimensional gravity. It was…

General Relativity and Quantum Cosmology · Physics 2016-11-24 Vakhid A. Gani , Alexander E. Dmitriev , Sergey G. Rubin

The possibility to detect cosmic strings -- topological defects of early Universe, by means of wave effects in gravitational lensing is discussed. To find the optimal observation conditions, we define the hyperbolic-shaped Fresnel…

Cosmology and Nongalactic Astrophysics · Physics 2017-05-05 Isabel Fernández-Núñez , Oleg Bulashenko

We study the impact of asymmetric bosonic dark matter on neutron star properties, including possible changes of tidal deformability, maximum mass, radius, and matter distribution inside the star. The conditions at which dark matter…

High Energy Astrophysical Phenomena · Physics 2023-01-11 Violetta Sagun , Edoardo Giangrandi , Oleksii Ivanytskyi , Costança Providência , Tim Dietrich

The predictions of the inflationary LCDM paradigm match today's high-precision measurements of the cosmic microwave background anisotropy extremely well. The same data put tight limits on other sources of anisotropy. Cosmic strings are a…

Cosmology and Nongalactic Astrophysics · Physics 2013-05-29 Cora Dvorkin , Mark Wyman , Wayne Hu

We study topological defects with a general structure in higher-dimensional cosmological backgrounds described by a set of angle deficit parameters. As special cases, they include higher-dimensional generalizations of cosmic strings and…

High Energy Physics - Theory · Physics 2026-01-29 A. A. Saharian , G. V. Mirzoyan , G. H. Harutyunyan , R. M. Avagyan

Brown dwarfs, stars with insufficient mass to burn hydrogen, could contribute to the dark matter in the Galactic disk, galactic halos or even a background critical density. We consider the detectability of such brown dwarfs in various…

Astrophysics · Physics 2015-06-24 E. J. Kerins , B. J. Carr
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