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The formalism for computing the gravitational power radiation from excitations on cosmic strings forming a junction is presented and applied to the simple case of co-planar strings at a junction when the excitations are generated along one…

High Energy Physics - Theory · Physics 2009-02-12 Robert Brandenberger , Hassan Firouzjahi , Johanna Karouby , Shahram Khosravi

For suitable cosmological backgrounds, thermal fluctuations of a gas of strings can generate a scale-invariant spectrum of cosmological fluctuations without requiring a phase of inflationary expansion. We highlight the key points of this…

High Energy Physics - Theory · Physics 2008-11-26 Robert Brandenberger

We calculate the deflection of a light ray caused by the gravitational field of a cosmic string loop in the weak field limit and reduce the problem to a single quadrature over a time slice of the loop's world sheet. We then apply this…

Astrophysics · Physics 2011-09-09 Andrew A de Laix , Tanmay Vachaspati

The combination of non-minimal couplings to gravity with the post-inflationary kinetic-dominated era typically appearing in quintessential inflation scenarios may lead to the spontaneous symmetry breaking of internal symmetries and its…

Cosmology and Nongalactic Astrophysics · Physics 2019-02-18 Dario Bettoni , Guillem Domènech , Javier Rubio

We study the effect of free streaming in a universe with cosmic strings with time-varying tension as well as with constant tension. Although current cosmological observations suggest that fluctuation seeded by cosmic strings cannot be the…

High Energy Physics - Phenomenology · Physics 2009-11-11 Tomo Takahashi , Masahide Yamaguchi

The mean spectrum and burst statistics of gravitational waves produced by a cosmological population of cosmic string loops are estimated using analytic approximations, calibrated with earlier simulations. Formulas are derived showing the…

Astrophysics · Physics 2009-11-11 Craig J. Hogan

We examine variations in the equation of state of the cosmic string portion of the cosmological fluid which lead to perturbations of the background matter density. These fluctuations in the equation of state are due to variations in the…

Astrophysics · Physics 2010-01-06 Pedro Avelino , Robert Caldwell

In an analysis of the gravitational lensing by two relativistic cosmic strings, we argue that the formation of closed time-like curves proposed by Gott is unstable in the presence of particles (e.g. the cosmic microwave background…

High Energy Physics - Theory · Physics 2009-11-11 Benjamin Shlaer , S. -H. Henry Tye

Many symmetry breaking patterns in grand unified theories (GUTs) give rise to cosmic strings that eventually decay when pairs of GUT monopoles spontaneously nucleate along the string cores. These strings are known as metastable cosmic…

High Energy Physics - Phenomenology · Physics 2024-01-23 Wilfried Buchmuller , Valerie Domcke , Kai Schmitz

The lowest order amplitudes for [$ {\rm graviton+graviton \rightarrow photon +photon}]$ lead to cross-sections of order $G^2$, where $G$ is the gravitational constant. These are too small to be of any interest. However in dense clouds of…

High Energy Physics - Theory · Physics 2020-03-18 R. F. Sawyer

Gravitational waves emitted by kinks on infinite strings are investigated using detailed estimations of the kink distribution on infinite strings. We find that gravitational waves from kinks can be detected by future pulsar timing…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 Masahiro Kawasaki , Koichi Miyamoto , Kazunori Nakayama

Cosmic strings are topological defects possibly formed in the early Universe, which may be observable due to their gravitational effects on the cosmic microwave background radiation or gravitational wave experiments. To this effect it is…

Cosmology and Nongalactic Astrophysics · Physics 2017-03-01 R. P. L. Azevedo , C. J. A. P. Martins

We examine the spectrum of gravitational radiation emitted by a network of cosmic strings, with emphasis on the observational constraints and the opportunities for detection. The analysis improves over past work, as we use a…

Astrophysics · Physics 2009-12-30 R. R. Caldwell , R. A. Battye , E. P. S. Shellard

Graviton-photon oscillation is the conversion of gravitational waves to electromagnetic waves and vice versa in the presence of a background electromagnetic field. We investigate this phenomenon in a cosmological scenario considering a…

General Relativity and Quantum Cosmology · Physics 2023-10-10 José A. R. Cembranos , Miguel González Ortiz , Prado Martín-Moruno

A network of cosmic strings (CS), if present, would continue emitting gravitational waves (GW) as it evolves throughout the history of the Universe. This results in a characteristic broad spectrum making it a perfect source to infer the…

Cosmology and Nongalactic Astrophysics · Physics 2023-09-12 Francesc Ferrer , Anish Ghoshal , Marek Lewicki

We study the relative contribution of cusps and pseudocusps, on cosmic (super)strings, to the emitted bursts of gravitational waves. The gravitational wave emission in the vicinity of highly relativistic points on the string follows, for a…

High Energy Physics - Theory · Physics 2017-08-02 Matthew J. Stott , Thomas Elghozi , Mairi Sakellariadou

We calculate the gravitational radiation from a cusp of the chiral cosmic strings as a function of the current on the string in the limit of small values of the current. The smoothing of the cosmic string cusp due to the presence of the…

Astrophysics · Physics 2009-11-07 Eugeny Babichev , Vyacheslav Dokuchaev

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 re-visit the production of cosmic rays by cusps on cosmic strings. If a scalar field (``Higgs'') has a linear interaction with the string world-sheet, such as would occur if there is a bosonic condensate on the string, cusps on string…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 Tanmay Vachaspati

Dark photon dark matter may be produced by the cosmic strings in association with the dark U(1) gauge symmetry breaking. We perform three-dimensional lattice simulations of the Abelian-Higgs model and follow the evolution of cosmic strings.…

High Energy Physics - Phenomenology · Physics 2023-08-04 Naoya Kitajima , Kazunori Nakayama