THE NANOGRAV NINE-YEAR DATA SET: LIMITS ON THE ISOTROPIC STOCHASTIC GRAVITATIONAL WAVE BACKGROUND

By Z. Arzoumanian, A. Brazier, S. Burke-Spolaor, S. Chamberlin, S. Chatterjee, B. Christy, J. Cordes, N. Cornish, K. Crowter, P. Demorest and 41 more. 2015

212 citations recorded by the source corpus.

We compute upper limits on the nanohertz-frequency isotropic stochastic gravitational wave background (GWB) using the 9 year data set from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) collaboration. Well-tested Bayesian techniques are used to set upper limits on the dimensionless strain amplitude (at a frequency of 1 yr−1) for a GWB from supermassive black hole binaries of A gw < 1.5 × 10 − 15 . We also parameterize the GWB spectrum with a broken power-law model by placing priors on the strain amplitude derived from simulations of Sesana and McWilliams et al. Using Bayesian model selection we find that the data favor a broken power law to a pure power law with odds ratios of 2.2 and 22 to one for the Sesana and McWilliams prior models, respectively. Using the broken power-law analysis we construct posterior distributions on environmental factors that drive the binary to the GW-driven regime including the stellar mass density for stellar-scattering, mass accretion rate for circumbinary disk interaction, and orbital eccentricity for eccentric binaries, marking the first time that the shape of the GWB spectrum has been used to make astrophysical inferences. Returning to a power-law model, we place stringent limits on the energy density of relic GWs, Ω gw ( f ) h 2 < 4.2 × 10 − 10 . Our limit on the cosmic string GWB, Ω gw ( f ) h 2 < 2.2 × 10 − 10 , translates to a conservative limit on the cosmic string tension with G μ < 3.3 × 10 − 8 , a factor of four better than the joint Planck and high-l cosmic microwave background data from other experiments.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/5e196fca5f3cdfe65574b65dff43c5ba9ee73aac

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In Astronomy and Astrophysics

1. G. Hobbs
2. R. Manchester
3. D. R. Lorimer
4. S. Burke-Spolaor
5. V. Ravi
6. P. Lasky
7. Willem van Straten
8. M. Bailes

Citations in the corpus

• The NANOGrav 11 Year Data Set: Pulsar-timing Constraints on the Stochastic Gravitational-wave Background (2018, methodology): “…sensitivity of PTAs is apparent in the evertightening upper limits (van Haasteren et al. 2011; Demorest et al. 2013; Shannon et al. 2013; Lentati et al. 2015; Shannon et al. 2015; Arzoumanian et al. 2016) on the stochastic GWB from the unresolved superposition of SMBHB signals out to redshift .”
• Primordial Black Holes from Polynomial Potentials in Single Field Inflation (2017, unknown): “The constraint on the energy density of gravitational waves by the pulsar-timing experiment, such as EPTA [51], PPTA [52], and NANOGrav [53], can be recast into that of the amplitude of scalar perturbation.”
• Gravitational-wave cosmology across 29 decades in frequency (2015, background): “3 × 10−10; more than a factor of four tighter than the previous best limit from [62].”
• New limits on cosmic strings from gravitational wave observation (2017, unknown): “X. S. was supported in part by the National Science Foundation under Grant No. 1430284 (NANOGrav Physics Frontiers Center) and No. 1607585.”
• The NANOGrav 11-year Data Set: High-precision Timing of 45 Millisecond Pulsars (2017, background): “Its detection is likely within a few years (Taylor et al. 2016), depending on the underlying astrophysics of supermassive black hole binary mergers (Kocsis & Sesana 2011; Roedig et al. 2012; Sampson et al. 2015; Arzoumanian et al. 2016; Taylor et al. 2017).”
• Searching for isotropic stochastic gravitational-wave background in the international pulsar timing array second data release (2021, unknown): “The fi fth term δ t WN represents the stochastic contribution due to the white noise ( WN ) , including a scale parameter on the TOA uncertainties ( EFAC ) , an added variance ( EQUAD ) , and a per-epoch variance ( ECORR ) for each backend / receiver system ( see e.g. [ 47 ] ) .”