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CMB anisotropies generated by cosmic string loops
Cosmology and Nongalactic Astrophysics · Submitted 16 Apr 2021
abstract compiled · 2026-09-23 · no language-model review
The authors' main claim This contribution may then be significant and, thus, this extension provides a more accurate prediction of the CMB anisotropies generated by cosmic string networks.
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The abstract, sentence by sentence
We investigate the contribution of cosmic string loops to the Cosmic Microwave Background (CMB) anisotropies. This is done by extending the Unconnected Segment Model (USM) to include the contribution of the cosmic string loops created throughout the cosmological evolution of a cosmic string network to the stress-energy tensor. We then implement this extended USM in the publicly available CMBACT code and obtain the linear CDM power spectrum and the CMB angular power spectra generated by cosmic string loops. We find that the shape of the angular power spectra generated by loops is, in general, similar to that of long strings. However, there is generally an enhancement of the anisotropies on small angular scales. Vector modes produced by loops dominate over those produced by long strings for large multipole moments $\ell$. The contribution of loops to the CMB anisotropies generated by cosmic string networks may reach a level of $10\%$ for large loops but decreases as the size of loops decreases. This contribution may then be significant and, thus, this extension provides a more accurate prediction of the CMB anisotropies generated by cosmic string networks.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | We investigate the contribution of cosmic string loops to the Cosmic Microwave Background (CMB) anisotropies. | contribution 0.92 | 0.89 | 0.03 | unclear 0.61 |
| s1 | This is done by extending the Unconnected Segment Model (USM) to include the contribution of the cosmic string loops created throughout the cosmological evolution of a cosmic string network to the stress-energy tensor. | method 0.96 | 0.90 | 0.03 | asserted 0.97 |
| s2 | We then implement this extended USM in the publicly available CMBACT code and obtain the linear CDM power spectrum and the CMB angular power spectra generated by cosmic string loops. | method 0.92 | 0.96 | 0.05 | asserted 1.00 |
| s3 | We find that the shape of the angular power spectra generated by loops is, in general, similar to that of long strings. | result 1.00 | 0.95 | 0.18 | asserted 0.98 |
| s4 | However, there is generally an enhancement of the anisotropies on small angular scales. | result 1.00 | 0.93 | 0.11 | asserted 0.88 |
| s5 | Vector modes produced by loops dominate over those produced by long strings for large multipole moments $\ell$. | result 1.00 | 0.91 | 0.12 | asserted 1.00 |
| s6 | The contribution of loops to the CMB anisotropies generated by cosmic string networks may reach a level of $10\%$ for large loops but decreases as the size of loops decreases. | result 1.00 | 0.87 | 0.31 | hedged possibility 1.00 |
| s7 | This contribution may then be significant and, thus, this extension provides a more accurate prediction of the CMB anisotropies generated by cosmic string networks. | interpretation 1.00 | 0.55 | 0.48 | hedged possibility 0.99 |
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Original abstract
We investigate the contribution of cosmic string loops to the Cosmic Microwave Background (CMB) anisotropies. This is done by extending the Unconnected Segment Model (USM) to include the contribution of the cosmic string loops created throughout the cosmological evolution of a cosmic string network to the stress-energy tensor. We then implement this extended USM in the publicly available CMBACT code and obtain the linear CDM power spectrum and the CMB angular power spectra generated by cosmic string loops. We find that the shape of the angular power spectra generated by loops is, in general, similar to that of long strings. However, there is generally an enhancement of the anisotropies on small angular scales. Vector modes produced by loops dominate over those produced by long strings for large multipole moments $\ell$. The contribution of loops to the CMB anisotropies generated by cosmic string networks may reach a level of $10\%$ for large loops but decreases as the size of loops decreases. This contribution may then be significant and, thus, this extension provides a more accurate prediction of the CMB anisotropies generated by cosmic string networks.
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References
How the literature uses it
11 arXiv papers cite this in 22 sentences
Papers citing it · 12 sentences without a confident label
Uses its method or tool 1 paper
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To include the impact of cosmic string loops on the anisotropies generated from NG string networks, we will follow the approach introduced in [ref] .
Cosmic strings and domain walls: the impact of CMB $B$-mode data · Including cosmic string loops in the USM · 1.00
Cites it as background 4 papers
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Additional sources of parity-violation include inflationary interactions between multiple fields, such as via the Chern-Simons term [ref] , generation of primordial magnetic fields [ref] , vector perturbations generated by cosmic strings or defects [ref] , reheating [ref] , Chern-Simons modified general relativity [ref] , and inflationary particle exchange [ref] , all of which leave distinctive imprints on late-time observables [ref] .
Probing Parity-Violation with the Four-Point Correlation Function of BOSS Galaxies · Introduction · 0.92
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A particularly sensitive and well-established probe to assess the presence of cosmic strings is the study of cosmic microwave background (CMB) anisotropies [ref] , which rely on linear physics, to which one may also add spectral distortions [ref] and lensing [ref] .
Cosmic Microwave Background Signatures from Current-carrying Cosmic Strings · Introduction · 0.93
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The (velocity-dependent) one-scale model was developed with this particular property in mind [ref] , and allows one to estimate the present power spectrum of the gravitational waves generated by cosmic strings as well as the contribution of the cosmic string network to the cosmic microwave background [ref] .
Dynamical simulations of colliding superconducting strings · Introduction · 0.87
What it cites · 63 sentences without a confident label
Builds on 2 papers
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This section extends the USM [ref] — which describes the stress-energy tensor of a cosmic string network — to also account for cosmic string loops.
A detail study of defect models for cosmic structure formation · An Unconnected Segment Model with Loops · 0.96
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This section extends the USM [ref] — which describes the stress-energy tensor of a cosmic string network — to also account for cosmic string loops.
Cosmic microwave background anisotropy from wiggly strings · An Unconnected Segment Model with Loops · 0.96
Uses the method or tool of 6 papers
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The number density of loops created per unit time is then given by [ref] : dn_l/dt=1/a l_c^b.dρ/dt|_loops=/α/a^4 L_c^4 .
Stochastic Gravitational Wave Background generated by Cosmic String Networks: Velocity-Dependent One-Scale model versus Scale-Invariant Evolution · Cosmic string network evolution and loop production · 0.88
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This may be achieved by using numerical simulations [ref] of cosmic string networks, through analytic estimation [ref] or by resorting to the publicly available CMBACT code [ref] .
CMB power spectrum of Nambu-Goto cosmic strings · Introduction · 0.91
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This may be achieved by using numerical simulations [ref] of cosmic string networks, through analytic estimation [ref] or by resorting to the publicly available CMBACT code [ref] .
Small-Angle CMB Temperature Anisotropies Induced by Cosmic Strings · Introduction · 0.91
Uses data or values from 12 papers
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Our results are obtained by averaging over 500 realizations of a brownian cosmic string network with the following cosmological parameters: $Ω^0_b h^2=0.0224$, $Ω^0_m h^2=0.1424$ for baryon and matter density parameters, and $H_0 = 100 h kms^-1 Mpc^-1$, with $h=0.674$ for the Hubble parameter at the present time [ref] .
Planck 2018 results. VI. Cosmological parameters · Cosmic Microwave Background anisotropies · 1.00
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Nambu-Goto simulations are well described by $=0.23$ and a momentum parameter of the form [ref] [equation] see Ref. [ref] for the latest calibration of these parameters from the simulation of Abelian-Higgs cosmic strings.
Extending the Velocity-dependent One-scale String Evolution Model · Cosmic string network evolution and loop production · 0.91
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Nambu-Goto simulations are well described by $=0.23$ and a momentum parameter of the form [ref] [equation] see Ref. [ref] for the latest calibration of these parameters from the simulation of Abelian-Higgs cosmic strings.
Extending and Calibrating the Velocity dependent One-Scale model for Cosmic Strings with One Thousand Field Theory Simulations · Cosmic string network evolution and loop production · 0.91
Cites as support 1 paper
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As a matter of fact it was shown in [ref] that loops indeed provide a significant contribution to the spectrum of perturbations generated by the cosmic string network, which may translate into a significant contribution to CMB anisotropies.
Cosmic strings, loops, and linear growth of matter perturbations · Introduction · 1.00
Cites as background 22 papers
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The evolution of topological defect networks has been extensively studied using numerical [ref] and semi-analytical [ref] methods.
One-scale Model for Domain Wall Network Evolution · Cosmic string network evolution and loop production · 0.95
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The evolution of topological defect networks has been extensively studied using numerical [ref] and semi-analytical [ref] methods.
Domain wall network evolution in (N+1)-dimensional FRW universes · Cosmic string network evolution and loop production · 0.95
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The evolution of topological defect networks has been extensively studied using numerical [ref] and semi-analytical [ref] methods.
Large parallel cosmic string simulations: New results on loop production · Cosmic string network evolution and loop production · 0.95
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