http://arxiv.org/abs/1710.08804
According to the Cosmological Principle, the matter distribution on very large scales should have a kinematic dipole that is aligned with that of the CMB. We determine the dipole anisotropy in the number counts of two all-sky surveys of radio galaxies. For the first time, this analysis is performed for the TGSS survey. This allows us to check consistency of the radio dipole at low and high frequencies by comparing the TGSS results with the well-known NVSS survey. After matching the flux thresholds of the catalogues and adopting a strict masking scheme, we find dipole directions that are in good agreement with each other and with the CMB dipole. However the amplitudes are higher than predicted, especially in the TGSS catalogue. We produce sets of lognormal realisations including galaxy clustering and the Poisson noise, in addition to simulated redshift distributions which fit well the NVSS and TGSS source counts. Even so, the measured dipole is still $3\sigma$ (NVSS) and $5\sigma$ (TGSS) above the predicted signal. More data will be needed in order to clarify this large discrepancy with the $\Lambda$CDM model.
C. Bengaly, R. Maartens and M. Santos
Wed, 25 Oct 17
65/68
Comments: 10 pages, 6 figures, 2 tables
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