Constraining the Solution to the Last Parsec Problem with Pulsar Timing

Abstract

The detection of a stochastic gravitational-wave signal from the superposition of many inspiraling supermassive black holes with pulsar timing arrays (PTAs) is likely to occur within the next decade. With this detection will come the opportunity to learn about the processes that drive black-hole-binary systems toward merger through their effects on the gravitational-wave spectrum. We use Bayesian methods to investigate the extent to which effects other than gravitational-wave emission can be distinguished using PTA observations. We show that, even in the absence of a detection, it is possible to place interesting constraints on these dynamical effects for conservative predictions of the population of tightly bound supermassive black-hole binaries. For instance, if we assume a relatively weak signal consistent with a low number of bound binaries and a low black-hole-mass to galaxy-mass correlation, we still find that a non-detection by a simulated array, with a sensitivity that should be reached in practice within a few years, disfavors gravitational-wave-dominated evolution with an odds ratio of $\sim$30:1. Such a finding would suggest either that all existing astrophysical models for the population of tightly bound binaries are overly optimistic, or else that some dynamical effect other than gravitational-wave emission is actually dominating binary evolution even at the relatively high frequencies/small orbital separations probed by PTAs.

14 pages, 8 figures

References in corpus (14)

• An Observational Determination of the Bolometric Quasar Luminosity Function
• The stochastic gravitational-wave background from massive black hole binary systems: implications for observations with Pulsar Timing Arrays
• BayesLine: Bayesian Inference for Spectral Estimation of Gravitational Wave Detector Noise
• Interaction of massive black hole binaries with their stellar environment: I. Ejection of hypervelocity stars
• Self consistent model for the evolution of eccentric massive black hole binaries in stellar environments: implications for gravitational wave observations
• An all-sky search for continuous gravitational waves in the Parkes Pulsar Timing Array data set
• NANOGrav Limits on Gravitational Waves from Individual Supermassive Black Hole Binaries in Circular Orbits
• The Effect of Orbital Eccentricity on Gravitational Wave Background Radiation from Supermassive Black Hole Binaries
• Prospects for gravitational-wave detection and supermassive black hole astrophysics with pulsar timing arrays
• Binary super-massive black hole environments diminish the gravitational-wave signal in the pulsar timing band
• A Bayesian Approach to the Detection Problem in Gravitational Wave Astronomy
• Accelerated Bayesian model-selection and parameter-estimation in continuous gravitational-wave searches with pulsar-timing arrays
• Linking the fate of massive black hole binaries to the active galactic nuclei luminosity function
• Pulsar timing arrays and the challenge of massive black hole binary astrophysics

Cited by in corpus (1)

• Expected properties of the first gravitational wave signal detected with pulsar timing arrays