Cosmic microwave background constraints for global strings and global monopoles
Abstract
We present the first cosmic microwave background (CMB) power spectra from numerical simulations of the global O( N ) linear σmodel, with N =2,3, which have global strings and monopoles as topological defects. In order to compute the CMB power spectra we compute the unequal time correlators (UETCs) of the energymomentum tensor, showing that they fall off at high wave number faster than naive estimates based on the geometry of the defects, indicating nontrivial (anti)correlations between the defects and the surrounding Goldstone boson field. We obtain source functions for EinsteinBoltzmann solvers from the UETCs, using a recently developed method that improves the modelling at the radiationmatter transition. We show that the interpolation function that mimics the transition is similar to other defect models, but not identical, confirming the nonuniversality of the interpolation function. The CMB power spectra for global strings and global monopoles have the same overall shape as those obtained using the nonlinear σmodel approximation, which is well captured by a large N calculation. However, the amplitudes are larger than the large N calculation would naively predict, and in the case of global strings much larger: a factor of 20 at the peak. Finally we compare the CMB powermore »
 Authors:
 Department of Theoretical Physics, University of the Basque Country UPV/EHU, 48080 Bilbao (Spain)
 Department of Physics and Astronomy, University of Sussex, Brighton, BN1 9QH (United Kingdom)
 Publication Date:
 OSTI Identifier:
 22676101
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2017; Journal Issue: 07; Other Information: Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; AMPLITUDES; APPROXIMATIONS; AXIONS; COMPARATIVE EVALUATIONS; COMPUTERIZED SIMULATION; DECOUPLING; ENERGYMOMENTUM TENSOR; GEV RANGE; GRAVITATIONAL WAVES; INTERPOLATION; MASS; MONOPOLES; MULTIPOLES; NONLINEAR PROBLEMS; RELICT RADIATION; SIGMA MODEL; SPECTRA; SYMMETRY BREAKING
Citation Formats
LopezEiguren, Asier, Lizarraga, Joanes, Urrestilla, Jon, and Hindmarsh, Mark, Email: asier.lopez@ehu.eus, Email: joanes.lizarraga@ehu.eus, Email: m.b.hindmarsh@sussex.ac.uk, Email: jon.urrestilla@ehu.eus. Cosmic microwave background constraints for global strings and global monopoles. United States: N. p., 2017.
Web. doi:10.1088/14757516/2017/07/026.
LopezEiguren, Asier, Lizarraga, Joanes, Urrestilla, Jon, & Hindmarsh, Mark, Email: asier.lopez@ehu.eus, Email: joanes.lizarraga@ehu.eus, Email: m.b.hindmarsh@sussex.ac.uk, Email: jon.urrestilla@ehu.eus. Cosmic microwave background constraints for global strings and global monopoles. United States. doi:10.1088/14757516/2017/07/026.
LopezEiguren, Asier, Lizarraga, Joanes, Urrestilla, Jon, and Hindmarsh, Mark, Email: asier.lopez@ehu.eus, Email: joanes.lizarraga@ehu.eus, Email: m.b.hindmarsh@sussex.ac.uk, Email: jon.urrestilla@ehu.eus. Sat .
"Cosmic microwave background constraints for global strings and global monopoles". United States.
doi:10.1088/14757516/2017/07/026.
@article{osti_22676101,
title = {Cosmic microwave background constraints for global strings and global monopoles},
author = {LopezEiguren, Asier and Lizarraga, Joanes and Urrestilla, Jon and Hindmarsh, Mark, Email: asier.lopez@ehu.eus, Email: joanes.lizarraga@ehu.eus, Email: m.b.hindmarsh@sussex.ac.uk, Email: jon.urrestilla@ehu.eus},
abstractNote = {We present the first cosmic microwave background (CMB) power spectra from numerical simulations of the global O( N ) linear σmodel, with N =2,3, which have global strings and monopoles as topological defects. In order to compute the CMB power spectra we compute the unequal time correlators (UETCs) of the energymomentum tensor, showing that they fall off at high wave number faster than naive estimates based on the geometry of the defects, indicating nontrivial (anti)correlations between the defects and the surrounding Goldstone boson field. We obtain source functions for EinsteinBoltzmann solvers from the UETCs, using a recently developed method that improves the modelling at the radiationmatter transition. We show that the interpolation function that mimics the transition is similar to other defect models, but not identical, confirming the nonuniversality of the interpolation function. The CMB power spectra for global strings and global monopoles have the same overall shape as those obtained using the nonlinear σmodel approximation, which is well captured by a large N calculation. However, the amplitudes are larger than the large N calculation would naively predict, and in the case of global strings much larger: a factor of 20 at the peak. Finally we compare the CMB power spectra with the latest CMB data in other to put limits on the allowed contribution to the temperature power spectrum at multipole l = 10 of 1.7% for global strings and 2.4% for global monopoles. These limits correspond to symmetrybreaking scales of 2.9× 10{sup 15} GeV (6.3× 10{sup 14} GeV with the expected logarithmic scaling of the effective string tension between the simulation time and decoupling) and 6.4× 10{sup 15} GeV respectively. The bound on global strings is a significant one for the ultralight axion scenario with axion masses m {sub a} ∼< 10{sup −28} eV . These upper limits indicate that gravitational waves from global topological defects will not be observable at the gravitational wave observatory LISA.},
doi = {10.1088/14757516/2017/07/026},
journal = {Journal of Cosmology and Astroparticle Physics},
number = 07,
volume = 2017,
place = {United States},
year = {Sat Jul 01 00:00:00 EDT 2017},
month = {Sat Jul 01 00:00:00 EDT 2017}
}

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