Cosmic string scaling in flat space

Vanchurin, Vitaly; Olum, Ken D.; Vilenkin, Alexander

doi:10.1103/physrevd.72.063514

Cited by 62 publications

(108 citation statements)

References 20 publications

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“…Several early studies [63,65,73,74] suggested that α should be smaller than (or close to) the gravitational back-reaction scale α ΓGµ, while more recent studies [75][76][77][78][79] suggest scales much closer -albeit 1 to 3 orders of magnitude smaller -to the characteristic lengthscale of the network. There are also recent studies which indicate that string loops might be formed with lengths similar to the string thickness [80][81][82].…”

Section: A Cosmic String Loop Emissionmentioning

confidence: 99%

Probing cosmic superstrings with gravitational waves

Sousa

Avelino

2016

Phys. Rev. D

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We compute the stochastic gravitational wave background generated by cosmic superstrings using a semi-analytical velocity-dependent model to describe their dynamics. We show that heavier string types may leave distinctive signatures on the stochastic gravitational wave background spectrum within the reach of present and upcoming gravitational wave detectors. We examine the physically motivated scenario in which the physical size of loops is determined by the gravitational backreaction scale and use NANOGRAV data to derive a conservative constraint of GµF < 3.2 × 10 −9 on the tension of fundamental strings. We demonstrate that approximating the gravitational wave spectrum generated by cosmic superstring networks using the spectrum generated by ordinary cosmic strings with reduced intercommuting probability (which is often done in the literature) leads, in general, to weaker observational constraints on GµF . We show that the inclusion of heavier string types is required for a more accurate characterization of the region of the (gs, GµF ) parameter space that may be probed using direct gravitational wave detectors. In particular, we consider the observational constraints that result from NANOGRAV data and show that heavier strings generate a secondary exclusion region of parameter space.

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Section: A Cosmic String Loop Emissionmentioning

confidence: 99%

Probing cosmic superstrings with gravitational waves

Sousa

Avelino

2016

Phys. Rev. D

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“…In order to derive the detection probability we must derive first the number of string inside the particle horizon which is model dependent. If we restrict ourselves to long strings alone we can use the value derived by [20] ( 10 3 ÷ 10 4 ).…”

Section: The Number Of Cosmic Strings and The Probability Of Their Obmentioning

confidence: 99%

Gravitational Lens Images Generated by Cosmic Strings

Sazhin¹,

Sazhina²,

Capaccioli³

et al. 2010

TOAAJ

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Abstract:In this review paper the current understanding on the properties of cosmic strings is shortly outlined with special emphasis on the observational signatures which can be expected both in the optical, through gravitational lensing, and in the radio, through anisotropies in the cosmic microwave background. The experience gathered during the long term investigation of the former candidate CSL-1 is also shortly summarized.Keywords: Cosmology, cosmic string, quasars, gravitational lensing, the CMBR anisotropy. COSMIC STRINGS: GENERALITIES AND THEIR ROLE IN PARTICLE PHYSICSThe topological defects of space-time known as cosmic strings were introduced in the late seventies by Kibble [1] and have been extensively discussed over the past decades by several authors [2,3].Their existence finds support in a large class of early Universe models based on the superstring theory [4][5][6]. Cosmic strings are in fact predicted by compactification models, in theories with extended additional dimensions, and are easily justified within the current inflationary scenarios. It is important to stress that in comparision with other topological defects such as monopoles, domain walls, textures, etc., cosmic strings are the most likely to exist.Nowadays, inflation finds a widespread consensus within the cosmological community and is in good agreement with observational astronomical data. On the other end, the braneantibrane inflationary mechanism is the most natural model arising from superstring theories (being one of the most promising to achieve a full description of the Universe at Planckian time-scales) theory tells us that, within this mechanism, inflation ends when the brane and the antibrane annihilate. This process is likely to generate an extremely rich spectrum of post-inflationary remnants. Cosmic strings are among the most likely remnants with a rather rich spectrum.Without any doubt, the discovery of any of such objects would lead to a quantum leap in many fields of fundamental physics and, more specifically, in understanding the rules of GUT and the processes occurring in the pre-inflationary Universe. The linear density of a string (or its tension) *Address correspondence to this author at the Sternberg Astronomical Institute, Moscow State University, University pr. 13, Moscow, Russia; Tel: +7 495 939 50 06; Fax: +7 495 932 88 41; E-mail: miksazhin@yandex.ru depends in fact on the symmetry breaking scale. The specific equation which links these two values depends both on the model of phase transition and on the specific form of the scalar field potential. In the case of a global U(1) string (i.e. the simplest case with winding number n = 1), the equation is, [7]:where vac is the energy density of the false vacuum and H is the Compton wavelenght of the Higgs boson. Here μ has dimension of linear density.The most relevant and, what is more important, model independent feature of cosmic strings is that they are one dimensional objects with diameter of the order of Planckian size of 10 33 cm. The microscopic charact...

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“…Cosmic strings are expected to move relativistically, β ∼ O(1) [1]; following [19,39], we use β ⊥ = 0.3 in subsequent calculations 2 . Since we assume that the source is lensed by at most one string, conditions in the argument of (6) require that the center of the source is inside the strip by a margin of at least the source size r ⊥ = R ⊥ /Dos (R ⊥ is its linear size) on the first observation and outside it by the same margin on the second epoch:…”

Section: Model: Probability As a Function Of Strings Populationmentioning

confidence: 99%

“…Analytical calculations and numerical simulations indicate that string networks, soon in the course of their evolution, can reach a scaling behavior where a typical distance between the strings increases in proportion to the horizon scale d h [4][5][6][7][8][9][10]. This corresponds to the density of strings ρ decreasing with redshift z as ρ(z) ∝ d −2 h (z) although one should keep in mind that these results were obtained for radiation-and matter-dominated eras with no contribution from the vacuum energy.…”

Section: Introductionmentioning

confidence: 99%

Quasar variability limits on cosmological density of cosmic strings

Tuntsov

Пширков

2010

Phys. Rev. D

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We put robust upper limits on the average cosmological density Ωs of cosmic strings based on the variability properties of a large homogeneous sample of SDSS quasars. We search for an excess of characteristic variations of quasar brightness that are associated with string lensing and use the observed distribution of this variation to constrain the density of strings. The limits obtained do not invoke any clustering of strings, apply to both open segments and closed loops of strings, usefully extend over a wide range of tensions 10 −13 < Gµ/c 2 < 10 −9 and reach down the level of Ωs = 0.01 and below. Further progress in this direction will depend on better understanding of quasar intrinsic variability rather than a mere increase in the volume of data.PACS numbers: 98.80. Cq, 98.54.Aj, 95.75.De,95.80.+p

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Cosmic string scaling in flat space

Cited by 62 publications

References 20 publications

Probing cosmic superstrings with gravitational waves

Probing cosmic superstrings with gravitational waves

Gravitational Lens Images Generated by Cosmic Strings

Quasar variability limits on cosmological density of cosmic strings

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