Updated constraints on the cosmic string tension

Journal Article · Thu Jul 15 00:00:00 EDT 2010 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.82.023521· OSTI ID:21415220

Battye, Richard ^[1]; Moss, Adam ^[2]

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1. Jodrell Bank Center for Astrophysics, University of Manchester, Manchester, M13 9PL (United Kingdom)
2. Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada)

We reexamine the constraints on the cosmic string tension from cosmic microwave background (CMB) and matter power spectra, and also from limits on a stochastic background of gravitational waves provided by pulsar timing. We discuss the different approaches to modeling string evolution and radiation. In particular, we show that the unconnected segment model can describe CMB spectra expected from thin string (Nambu) and field theory (Abelian-Higgs) simulations using the computed values for the correlation length, rms string velocity and small-scale structure relevant to each variety of simulation. Applying the computed spectra in a fit to CMB and SDSS data we find that G{mu}/c{sup 2}<2.6x10{sup -7} (2{sigma}) if the Nambu simulations are correct and G{mu}/c{sup 2}<6.4x10{sup -7} in the Abelian-Higgs case. The degeneracy between G{mu}/c{sup 2} and the power spectrum slope n{sub S} is substantially reduced from previous work. Inclusion of constraints on the baryon density from big bang nucleosynthesis (BBN) imply that n{sub S}<1 at around the 4{sigma} level for both the Nambu and Abelian-Higgs cases. As a by-product of our results, we find there is ''moderate-to-strong'' Bayesian evidence that the Harrison-Zel'dovich spectrum is excluded (odds ratio of {approx}100 ratio 1) by the combination of CMB, SDSS, and BBN when compared to the standard 6 parameter fit. Using the contribution to the gravitational wave background from radiation era loops as a conservative lower bound on the signal for specific values of G{mu}/c{sup 2} and loop production size, {alpha}, we find that G{mu}/c{sup 2}<7x10{sup -7} for {alpha}c{sup 2}/({Gamma}G{mu})<<1 and G{mu}/c{sup 2}<5x10{sup -11}/{alpha} for {alpha}c{sup 2}/({Gamma}G{mu})>>1.

• OSTI ID: 21415220
• Journal Information: Physical Review. D, Particles Fields, Vol. 82, Issue 2; Other Information: DOI: 10.1103/PhysRevD.82.023521; (c) 2010 The American Physical Society; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
BARYONS
BY-PRODUCTS
CORRELATIONS
DENSITY
FIELD THEORIES
GRAVITATIONAL WAVES
HIGGS BOSONS
HIGGS MODEL
NUCLEOSYNTHESIS
PULSARS
RELICT RADIATION
SIMULATION
SPECTRA
STOCHASTIC PROCESSES
VELOCITY
BOSONS
COSMIC RADIO SOURCES
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
FERMIONS
HADRONS
MATHEMATICAL MODELS
MICROWAVE RADIATION
PARTICLE MODELS
PHYSICAL PROPERTIES
POSTULATED PARTICLES
RADIATIONS
SYNTHESIS