Revised bounds on local cosmic strings from NANOGrav observations

Abstract

In a recent paper, the NANOGrav collaboration studied new physics explanations of the observed pulsar timing residuals consistent with a stochastic gravitational wave background (SGWB), including cosmic strings in the Nambu-Goto (NG) approximation. Analysing one of current models for the loop distribution, it was found that the cosmic string model is disfavored compared to other sources, for example, super massive black hole binaries (SMBHBs). When both SMBHB and cosmic string models are included in the analysis, an upper bound on a string tension $G\mu \lesssim 10^{-10}$ was derived. However, the analysis did not accommodate results from cosmic string simulations in an underlying field theory, which indicate that at most a small fraction of string loops survive long enough to emit GW. Following and extending our previous study, we suppose that a fraction $f_{\mathrm{NG}}$ of string loops follow NG dynamics and emit only GWs, and study the three different models of the loop distribution discussed in the LIGO-Virgo-KAGRA (LVK) collaboration analyses. We re-analyze the NANOGrav 15yrs data with our signal models by using the NANOGrav $\text{ENTERPRISE}$ analysis code via the wrapper $\text{PTArcade}$. We find that loop distributions similar to LVK Model B and C yield higher Bayes factor than Model A analyzed in the NANOGrav paper, as they can more easily accommodate a blue-tilted spectrum of the observed amplitude. Furthermore, because of the degeneracy of $G\mu$ and $f_{\mathrm{NG}}$ in determining the signal amplitude, our posterior distribution extends to higher values of $G\mu$, and in some cases the uppermost value of credible intervals is close to the Cosmic Microwave Background limit $G\mu \lesssim 10^{-7}$. Hence, in addition to the pulsar timing array data, further information about the fraction of long-lived loops in a cosmic string network is required to constrain the string tension.

22 pages, 9 figures; v3: matched to the version published in JCAP

References in corpus (52)

• Planck 2015 results. XIII. Cosmological parameters
• Planck 2013 results. I. Overview of products and scientific results
• The NANOGrav 15-year Data Set: Evidence for a Gravitational-Wave Background
• Search for an isotropic gravitational-wave background with the Parkes Pulsar Timing Array
• Searching for the nano-Hertz stochastic gravitational wave background with the Chinese Pulsar Timing Array Data Release I
• The second data release from the European Pulsar Timing Array III. Search for gravitational wave signals
• The NANOGrav 15-year Data Set: Search for Signals from New Physics
• European Pulsar Timing Array Limits On An Isotropic Stochastic Gravitational-Wave Background
• Gravitational waves from binary supermassive black holes missing in pulsar observations
• The NANOGrav 11-year Data Set: Pulsar-timing Constraints On The Stochastic Gravitational-wave Background
• The number of cosmic string loops
• Probing the gravitational wave background from cosmic strings with LISA
• Stochastic gravitational wave background from smoothed cosmic string loops
• CMB power spectrum contribution from cosmic strings using field-evolution simulations of the Abelian Higgs model
• Constraints on cosmic strings using data from the third Advanced LIGO-Virgo observing run
• New limits on cosmic strings from gravitational wave observation
• Beyond the Standard Models with Cosmic Strings
• Cosmic string loop distribution on all length scales and at any redshift
• Abelian Higgs Cosmic Strings: Small Scale Structure and Loops
• Signals of Inflationary Models with Cosmic Strings
• Stochastic gravitational waves from cosmic string loops in scaling
• CMB power spectra from cosmic strings: predictions for the Planck satellite and beyond
• Decay of Cosmic String Loops Due to Particle Radiation
• Seeking String Theory in the Cosmos
• Analytic Study of Small Scale Structure on Cosmic Strings
• Comparison of cosmic string and superstring models to NANOGrav 12.5-year results
• New CMB constraints for Abelian Higgs cosmic strings
• The nanohertz stochastic gravitational wave background from cosmic string loops and the abundant high redshift massive galaxies
• Bayesian model selection without evidences: application to the dark energy equation-of-state
• Superheavy quasi-stable strings and walls bounded by strings in the light of NANOGrav 15 year data
• Full analytical approximation to the stochastic gravitational wave background generated by cosmic string networks
• Particle emission and gravitational radiation from cosmic strings: observational constraints
• Loop decay in Abelian-Higgs string networks
• Cosmic string loop production functions
• Extending and Calibrating the Velocity dependent One-Scale model for Cosmic Strings with One Thousand Field Theory Simulations
• Effective non-intercommutation of local cosmic strings at high collision speeds
• Multi-messenger constraints on Abelian-Higgs cosmic string networks
• Towards distinguishing Dirac from Majorana neutrino mass with gravitational waves
• Inflation, superheavy metastable strings and gravitational waves in non-supersymmetric flipped SU(5)
• Big-Bang Nucleosynthesis and Gamma-Ray Constraints on Cosmic Strings with a large Higgs condensate
• Energy-conservation constraints on cosmic string loop production and distribution functions
• From quantum gravity to gravitational waves through cosmic strings
• Practical approaches to analyzing PTA data: Cosmic strings with six pulsars
• Testing Realistic $SO(10)$ SUSY GUTs with Proton Decay and Gravitational Waves
• Gravitational Wave Emission from a Cosmic String Loop, I: Global Case
• Probing Stochastic Gravitational Wave Background from $SU(5)\times U(1{)}_{\chi }$ Strings in Light of NANOGrav 15-Year Data
• Gravitational wave emission from metastable current-carrying strings in $E_6$
• Flipped SU(5): unification, proton decay, fermion masses and gravitational waves
• Quantifying the effect of cooled initial conditions on cosmic string network evolution
• Dark Matter from Decaying Topological Defects
• Scaling in necklaces of monopoles and semipoles
• Gravitational waves from cosmic superstrings and gauge strings

Cited by in corpus (9)

• Gravitational wave and particle emission from a cosmic string loop: local case
• Cosmic (super)strings with a time-varying tension
• Fundamental Physics and Cosmology with TianQin
• Implications for Pulsar Timing Arrays of Sub-solar Black Hole Detections: From LVK to Einstein Telescope and Cosmic Explorer
• Implications of pulsar timing arrays for Gauss-Bonnet Inflation
• Gravitational waves from low-scale cosmic strings without scaling
• Cosmic Strings-induced CMB anisotropies in light of Weighted Morphology
• From $U(1)\times U(1)$ Symmetry Breaking to Majoron Cosmology: Insights from NANOGrav 15-year Data
• Searching Stochastic Gravitational Wave Background Landscape Across Frequency Bands