A large disparity in cosmic reference frames determined from the sky distributions of radio sources and the microwave background radiation

Abstract

The angular distribution of the Cosmic Microwave Background Radiation (CMBR) in sky shows a dipole asymmetry, ascribed to the observer's motion (peculiar velocity of the solar system!), relative to the local comoving coordinates. The peculiar velocity thus determined turns out to be $370$ km s${}^{-1}$ in the direction RA$=168^{\circ }$, Dec$=-7^{\circ }$. On the other hand, a dipole asymmetry in the sky distribution of radio sources in the NRAO VLA Sky Survey (NVSS) catalog, comprising 1.8 million sources, yielded a value for the observer's velocity to be $\sim 4$ times larger than the CMBR value, though the direction turned out to be in agreement with that of the CMBR dipole. This large difference in observer's speeds with respect to the reference frames of NVSS radio sources and of CMBR, confirmed since by many independent groups, is rather disconcerting as the observer's motion with respect to local comoving coordinates should be independent of the technique used to determine it. A genuine difference in relative speeds of two cosmic reference frames could jeopardize the cosmological principle, thence it is crucial to confirm such discrepancies using independent samples of radio sources. We here investigate the dipole in the sky distribution of radio sources in the recent TIFR GMRT Sky Survey (TGSS) dataset, comprising 0.62 million sources, to determine observer's motion. We find a significant disparity in observer's speeds relative to all three reference frames, determined from the radio source datasets and the CMBR, which does not fit with the cosmological principle, a starting point for the standard modern cosmology.

arXiv comment8 pages, 4 tables, 2 figures

References in corpus (16)

• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Data Processing, Sky Maps, and Basic Results
• The GMRT 150 MHz All-sky Radio Survey: First Alternative Data Release TGSS ADR1
• The Dipole Observed in the COBE DMR Four-Year Data
• Cosmic radio dipole from NVSS and WENSS
• Detection of the velocity dipole in the radio galaxies of the NRAO VLA Sky Survey
• Large peculiar motion of the solar system from the dipole anisotropy in sky brightness due to distant radio sources
• Dipoles in the Sky
• High redshift radio galaxies and divergence from the CMB dipole
• Probing the Cosmological Principle in the counts of radio galaxies at different frequencies
• A radio spectral index map and catalogue at 147-1400 MHz covering 80 per cent of the sky
• Dipole anisotropy in sky brightness and source count distribution in radio NVSS data
• Searching for Large Scale Structure in Deep Radio Surveys
• Detecting the Cosmic Dipole Anisotropy in Large-Scale Radio Surveys
• Radio spectral index from NVSS and TGSS
• Comment on "Cosmic radio dipole from NVSS and WENSS"
• Clustering properties of TGSS radio sources

Cited by in corpus (28)

• Challenges for $\Lambda$CDM: An update
• The CosmoVerse White Paper: Addressing observational tensions in cosmology with systematics and fundamental physics
• A Test of the Cosmological Principle with Quasars
• Is the Observable Universe Consistent with the Cosmological Principle?
• The Cosmic Radio Dipole: Estimators and Frequency Dependence
• $\Lambda$CDM Tensions: Localising Missing Physics through Consistency Checks
• Inference of the cosmic rest-frame from supernovae Ia
• Testing cosmic anisotropy with Pantheon sample and quasars at high redshifts
• Peculiar motion of Solar system from the Hubble diagram of supernovae Ia and its implications for cosmology
• The Cosmic Dipole in the Quaia Sample of Quasars: A Bayesian Analysis
• The deceleration parameter in `tilted' universes: generalising the Friedmann background
• Discordance of dipole asymmetries seen in recent large radio surveys with the Cosmological Principle
• Explaining Excess Dipole in NVSS Data Using Superhorizon Perturbation
• Reassessment of the dipole in the distribution of quasars on the sky
• Resolution of the incongruency of dipole asymmetries within various large radio surveys -- implications for the Cosmological Principle
• Cosmic dipoles of active galactic nuclei at optical and radio wavelengths display much larger amplitudes than the cosmic microwave background dipole
• Testing the Cosmological Principle: On the Time Dilation of Distant Sources
• The MeerKAT Absorption Line Survey: Homogeneous continuum catalogues towards a measurement of the cosmic radio dipole
• QCD axion dark matter and the cosmic dipole problem
• Dipolar fluence distribution of statistically isotropic FERMI gamma-ray bursts
• Cosmological nanolensing by dense gas clouds
• Solar system peculiar motion from the Hubble diagram of quasars and testing the Cosmological Principle
• Horizon, homogeneity and flatness problems -- do their resolutions really depend upon inflation?
• Solar peculiar motion inferred from dipole anisotropy in redshift distribution of quasars appears to lie along the Galactic Centre direction
• Our Peculiar Motion Inferred from Number Counts of Mid Infra Red AGNs and the Discordance Seen with the Cosmological Principle
• Testing the cosmological principle on gigaparsec scales
• Measuring peculiar velocity and tomographic redshift dipole with DESI DR1 catalogs
• Galaxy number-count dipole and superhorizon fluctuations