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Pulsar timing arrays within rotating and expanding Universe

Davor Palle

TL;DR

This work challenges the interpretation of pulsar timing array signals as a stochastic gravitational wave background by showing that vortical geodesic motion of photons in a rotating and expanding Universe can reproduce the observed timing residuals and angular correlations. It develops a shearless GR cosmology with expansion, vorticity, and acceleration, and derives photon geodesics via Killing vectors, yielding residuals $R(T)$ that scale as $T^{2}$ and are proportional to the vorticity $\omega_0$. The induced angular correlation $\eta(x)$ closely matches the Hellings-Downs curve, enabling an estimate of $\omega_0$ of ${\cal O}(10^{-5}H_0)$ from PTA amplitudes, and it predicts a CMB polarization rotation $\beta$ of ${\cal O}(10^{-2})$ rad, compatible with observations, suggesting a right-handed cosmic rotation consistent with Einstein-Cartan cosmology.

Abstract

Recent measurements of the four pulsar timing arrays were interpreted as a signal of the low frequency stochastic gravitational wave background. We show that the amplitude and angular correlations of pulsar timing residuals can be interpreted as a consequence of the vortical geodetic motions of pulsar's photons within rotating and expanding Universe. The resulting angular correlation curves are similar to the Hellings-Downs curve and the observed amplitude allows the estimate of the vorticity of the Universe. We show that the estimated vorticity is compatible with the observed rotation of the CMB polarization vector.

Pulsar timing arrays within rotating and expanding Universe

TL;DR

This work challenges the interpretation of pulsar timing array signals as a stochastic gravitational wave background by showing that vortical geodesic motion of photons in a rotating and expanding Universe can reproduce the observed timing residuals and angular correlations. It develops a shearless GR cosmology with expansion, vorticity, and acceleration, and derives photon geodesics via Killing vectors, yielding residuals that scale as and are proportional to the vorticity . The induced angular correlation closely matches the Hellings-Downs curve, enabling an estimate of of from PTA amplitudes, and it predicts a CMB polarization rotation of rad, compatible with observations, suggesting a right-handed cosmic rotation consistent with Einstein-Cartan cosmology.

Abstract

Recent measurements of the four pulsar timing arrays were interpreted as a signal of the low frequency stochastic gravitational wave background. We show that the amplitude and angular correlations of pulsar timing residuals can be interpreted as a consequence of the vortical geodetic motions of pulsar's photons within rotating and expanding Universe. The resulting angular correlation curves are similar to the Hellings-Downs curve and the observed amplitude allows the estimate of the vorticity of the Universe. We show that the estimated vorticity is compatible with the observed rotation of the CMB polarization vector.
Paper Structure (3 sections, 26 equations, 3 figures)

This paper contains 3 sections, 26 equations, 3 figures.

Table of Contents

  1. Introduction and motivation
  2. Geodetic motions in a rotating Universe
  3. Anomalous timing residuals, angular correlations and conclusions

Figures (3)

  • Figure 1: Angular correlations of timing residuals: $\theta_{A}=\phi_{A}=0,\ m=10^{-4},\ \lambda=10^{-1},\ T=1yr.$
  • Figure 2: Solid curve is $\eta (x)$ and dashed line is the Hellings-Downs $\zeta (x)$ curve. Parameters for $\eta$ are the same as in Fig.1 and $\sigma^{2}_{rot}=1.27\times 10^{-32} yr^{2}$.
  • Figure 3: Solid curve is $\eta (x)$ with dashed line Hellings-Downs $\zeta (x)$ curve. Parameters are $\theta_{A}=0.7,\ \phi_{A}=-2.4, m=10^{-4},\ \lambda=10^{-1},\ T=1yr$ and $\sigma^{2}_{rot}=1.585 \times10^{-32} yr^{2}$.