Constraining string cosmology with the gravitational-wave background using the NANOGrav 15-year data set

Abstract

The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) collaboration has recently reported strong evidence for a signal at nanohertz, potentially the first detection of the stochastic gravitational-wave background (SGWB). We investigate whether the NANOGrav signal is consistent with the SGWB predicted by string cosmology models. By performing Bayesian parameter estimation on the NANOGrav 15-year data set, we constrain the key parameters of a string cosmology model: the frequency $f_s$ and the fractional energy density ${\Omega }_{\mathrm{gw}}^s$ of gravitational waves at the end of the dilaton-driven stage, and the Hubble parameter $H_r$ at the end of the string phase. Our analysis yields constraints of $f_s=1.2_{-0.6}^{+0.6}\times 10^{-8}\mathrm{Hz}$ and ${\Omega }_{\mathrm{gw}}^s=2.9_{-2.3}^{+5.4}\times 10^{-8}$, consistent with theoretical predictions from string cosmology. However, the current NANOGrav data is not sensitive to the $H_r$ parameter. We also compare the string cosmology model to a simple power-law model using Bayesian model selection, finding a Bayes factor of $2.2$ in favor of the string cosmology model. Our results demonstrate the potential of pulsar timing arrays to constrain cosmological models and study the early Universe.

15 pages, 2 figures, references added

References in corpus (70)

• Observation of Gravitational Waves from a Binary Black Hole Merger
• GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
• GWTC-1: A Gravitational-Wave Transient Catalog of Compact Binary Mergers Observed by LIGO and Virgo during the First and Second Observing Runs
• GWTC-2: Compact Binary Coalescences Observed by LIGO and Virgo During the First Half of the Third Observing Run
• dynesty: A Dynamic Nested Sampling Package for Estimating Bayesian Posteriors and Evidences
• GWTC-3: Compact Binary Coalescences Observed by LIGO and Virgo During the Second Part of the Third Observing Run
• 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
• Bilby: A user-friendly Bayesian inference library for gravitational-wave astronomy
• 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
• Inflationary spacetimes are not past-complete
• The stochastic gravitational-wave background from massive black hole binary systems: implications for observations with Pulsar Timing Arrays
• Bayesian inference for compact binary coalescences with BILBY: Validation and application to the first LIGO--Virgo gravitational-wave transient catalogue
• The NANOGrav 15-year Data Set: Constraints on Supermassive Black Hole Binaries from the Gravitational Wave Background
• The NANOGrav 15-year Data Set: Observations and Timing of 68 Millisecond Pulsars
• The second data release from the European Pulsar Timing Array I. The dataset and timing analysis
• Implications of the NANOGrav results for inflation
• The Parkes Pulsar Timing Array Third Data Release
• The recent gravitational wave observation by pulsar timing arrays and primordial black holes: the importance of non-gaussianities
• Inflationary interpretation of the stochastic gravitational wave background signal detected by pulsar timing array experiments
• Pulsar Timing Array Constraints on Primordial Black Holes with NANOGrav 11-Year Data Set
• Primordial gravitational waves from NANOGrav: a broken power-law approach
• Stochastic Gravitational-Wave Background from Binary Black Holes and Binary Neutron Stars and Implications for LISA
• Probing the equation of state of the early Universe with pulsar timing arrays
• Implications for the non-Gaussianity of curvature perturbation from pulsar timing arrays
• First-order Phase Transition interpretation of PTA signal produces solar-mass Black Holes
• The Need For Speed: Rapid Refitting Techniques for Bayesian Spectral Characterization of the Gravitational Wave Background Using PTAs
• The nanohertz stochastic gravitational wave background from cosmic string loops and the abundant high redshift massive galaxies
• Have pulsar timing array methods detected a cosmological phase transition?
• Gravitational Waves from SMBH Binaries in Light of the NANOGrav 15-Year Data
• The Detected Stochastic Gravitational Waves and Subsolar-Mass Primordial Black Holes
• Implications for the Supermassive Black Hole Binaries from the NANOGrav 15-year Data Set
• Implications of Pulsar Timing Array Data for Scalar-Induced Gravitational Waves and Primordial Black Holes: Primordial Non-Gaussianity $f_{\mathrm{NL}}$ Considered
• Can supercooled phase transitions explain the gravitational wave background observed by pulsar timing arrays?
• Constraints on primordial curvature power spectrum with pulsar timing arrays
• Confronting sound speed resonance with pulsar timing arrays
• Search for the Gravitational-wave Background from Cosmic Strings with the Parkes Pulsar Timing Array Second Data Release
• Ultra-low frequency gravitational waves from cosmological and astrophysical processes
• Translating nano-Hertz gravitational wave background into primordial perturbations taking account of the cosmological QCD phase transition
• NANOGrav spectral index $\gamma =3$ from melting domain walls
• Cosmological Interpretation for the Stochastic Signal in Pulsar Timing Arrays
• Implications of Nano-Hertz Gravitational Waves on Electroweak Phase Transition in the Singlet Dark Matter Model
• Constraining the Polarization of Gravitational Waves with the Parkes Pulsar Timing Array Second Data Release
• Search for Stochastic Gravitational-Wave Background from Massive Gravity in the NANOGrav 12.5-Year Data Set
• Induced Gravitational Wave interpretation of PTA data: a complete study for general equation of state
• Simultaneously probing the sound speed and equation of state of the early Universe with pulsar timing arrays
• Mirror QCD phase transition as the origin of the nanohertz Stochastic Gravitational-Wave Background
• Model-independent reconstruction of the primordial curvature power spectrum from PTA data
• Broken blue-tilted inflationary gravitational waves: a joint analysis of NANOGrav 15-year and BICEP/Keck 2018 data
• Searching for Isotropic Stochastic Gravitational-Wave Background in the International Pulsar Timing Array Second Data Release
• Exploring the NANOGrav Signal and Planet-mass Primordial Black Holes through Higgs Inflation
• Implication of nano-Hertz stochastic gravitational wave on dynamical dark matter through a dark first-order phase transition
• Probing the speed of scalar-induced gravitational waves with pulsar timing arrays
• Primordial non-Gaussianity as a saviour for PBH overproduction in SIGWs generated by Pulsar Timing Arrays for Galileon inflation
• NANOGrav hints for first-order confinement-deconfinement phase transition in different QCD-matter scenarios
• Large fluctuations and Primordial Black Holes
• Implications of the pulsar timing array detections for massive black hole mergers in the LISA band
• Search for Non-Tensorial Gravitational-Wave Backgrounds in the NANOGrav 15-Year Data Set
• Null energy condition violation during inflation and pulsar timing array observations
• Constraining the Graviton Mass with the NANOGrav 15-Year Data Set
• Unraveling the early universe's equation of state and primordial black hole production with PTA, BBN, and CMB observations
• Obviating PBH overproduction for SIGWs generated by Pulsar Timing Arrays in loop corrected EFT of bounce
• Constraints on the velocity of gravitational waves from NANOGrav 15-year data set
• Status Report on Global Pulsar-Timing-Array Efforts to Detect Gravitational Waves
• Charting the Nanohertz Gravitational Wave Sky with Pulsar Timing Arrays
• Can we distinguish the adiabatic fluctuations and isocurvature fluctuations with pulsar timing arrays?
• Search for stochastic gravitational-wave background from string cosmology with Advanced LIGO and Virgo's O1$\sim$O3 data
• Constraining inflation with nonminimal derivative coupling with the Parkes Pulsar Timing Array third data release

Cited by in corpus (4)

• Implications of pulsar timing arrays for Gauss-Bonnet Inflation
• Probing cosmic strings via gravitational-wave lensing
• Manifestation of Quantum Forces in Spacetime: Towards a General Theory of Quantum Forces
• A simple example of "non-minimal" Pre-Big Bang scenario