Looking out for the Galileon in the nanohertz gravitational wave sky

Abstract

We study the polarizations induced by the Galileon as a stochastic gravitational wave background in the cross correlated power in a pulsar timing array. Working within Galileon gravity, we first show that the scalar gravitational wave signature of the Galileon is encoded solely in its effective mass, which is controlled by the bare mass, conformal coupling, and a tadpole. Then, we study the phenomenology of the Galileon induced scalar polarizations and place observational constraints on these using the present NANOGrav data set. Our results feature longitudinal spatial correlation, indicative of a $10^{-22}$ eV {subluminal} Galileon, and show the Galileon polarizations as a statistically compelling source of the observed spatial correlation across millisecond pulsars, if there is any.

6 pages + refs + supp, 4 figures, 1 table, v3: to appear in PLB, our codes in https://github.com/reggiebernardo/galileon_pta

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Cited by in corpus (11)

• Inflationary interpretation of the stochastic gravitational wave background signal detected by pulsar timing array experiments
• Pulsar and cosmic variances of pulsar timing-array correlation measurements of the stochastic gravitational wave background
• Constraining gravitational wave propagation using pulsar timing array correlations
• Hunting the stochastic gravitational wave background in pulsar timing array cross correlations through theoretical uncertainty
• Search for Non-Tensorial Gravitational-Wave Backgrounds in the NANOGrav 15-Year Data Set
• Testing gravity with cosmic variance-limited pulsar timing array correlations
• Beyond the Hellings-Downs curve: Non-Einsteinian gravitational waves in pulsar timing array correlations
• Charting the Nanohertz Gravitational Wave Sky with Pulsar Timing Arrays
• Correlations for an anisotropic polarized stochastic gravitational wave background in pulsar timing arrays
• Toward a test of Gaussianity of a gravitational wave background
• Tadpole Cosmology: Milne Solution as a Cosmological Constant Hideout