Probing statistical isotropy of cosmological radio sources using SKA
arXiv:1610.08176 · doi:10.1007/s12036-016-9395-8
Abstract
There currently exist many observations which are not consistent with the cosmological principle. We review these observations with a particular emphasis on those relevant for Square Kilometre Array (SKA). In particular, several different data sets indicate a preferred direction pointing approximately towards the Virgo cluster. We also observe a hemispherical anisotropy in the Cosmic Microwave Background Radiation (CMBR) temperature fluctuations. Although these inconsistencies may be attributed to systematic effects, there remains the possibility that they indicate new physics and various theories have been proposed to explain them. One possibility, which we discuss in this review, is the generation of perturbation modes during the early pre-inflationary epoch, when the Universe may not obey the cosmological principle. Better measurements will provide better constraints on these theories. In particular, we propose measurement of the dipole in number counts, sky brightness, polarized flux and polarization orientations of radio sources. We also suggest test of alignment of linear polarizations of sources as a function of their relative separation. Finally we propose measurement of hemispherical anisotropy or equivalently dipole modulation in radio sources.
arXiv comment19 pages, To appear in Journal of Astrophysics and Astronomy (JAA) special issue on "Science with the SKA: an Indian perspective"
References in corpus (51)
- Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Data Processing, Sky Maps, and Basic Results
- The significance of the largest scale CMB fluctuations in WMAP
- Seven-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Are There Cosmic Microwave Background Anomalies?
- Planck 2013 results. XXIII. Isotropy and statistics of the CMB
- Dipole Anisotropy in the COBE DMR First-Year Sky Maps
- Stochastic Nonlinear Galaxy Biasing
- A semi-empirical simulation of the extragalactic radio continuum sky for next generation radio telescopes
- Testing the cosmological principle of isotropy: local power spectrum estimates of the WMAP data
- Hemispherical power asymmetry in the three-year Wilkinson Microwave Anisotropy Probe sky maps
- The Uncorrelated Universe: Statistical Anisotropy and the Vanishing Angular Correlation Function in WMAP Years 1-3
- Increasing evidence for hemispherical power asymmetry in the five-year WMAP 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
- Revisiting the NVSS number count dipole
- Anomalous parity asymmetry of the Wilkinson Microwave Anisotropy Probe power spectrum data at low multipoles
- The Virgo Alignment Puzzle in Propagation of Radiation on Cosmological Scales
- Constraints on cosmic hemispherical power anomalies from quasars
- Anisotropy in the Distribution of Galactic Radio Polarizations
- Dipole anisotropy in sky brightness and source count distribution in radio NVSS data
- Constraints on mode couplings and modulation of the CMB with WMAP data
- Statistical Isotropy of the Wilkinson Microwave Anisotropy Probe Data: A Bipolar Power Spectrum Analysis
- Observations of magnetic fields in the Milky Way and in nearby galaxies with a Square Kilometre Array
- Broken Isotropy from a Linear Modulation of the Primordial Perturbations
- Large Scale Alignment of Optical Polarizations from Distant QSOs using Coordinate Invariant Statistics
- Dipole Anisotropy in Integrated Linearly Polarized Flux Density in NVSS Data
- Testing Isotropy of Cosmic Microwave Background Radiation
- Parity Asymmetry in the CMBR Temperature Power Spectrum
- Dipolar modulation in number counts of WISE-2MASS sources
- Translational Invariance and the Anisotropy of the Cosmic Microwave Background
- Searching for a dipole modulation in the large-scale structure of the Universe
- A dipole anisotropy of galaxy distribution: Does the CMB rest-frame exist in the local universe?
- Signals of Statistical Anisotropy in WMAP Foreground-Cleaned Maps
- Polarization as an indicator of intrinsic alignment in radio weak lensing
- Large scale anisotropy due to pre-inflationary phase of cosmic evolution
- Direction dependence of the power spectrum and its effect on the Cosmic Microwave Background Radiation
- Testing the Dipole Modulation Model in CMBR
- Cross-correlation cosmic shear with the SDSS and VLA FIRST surveys
- Polarization alignments of radio quasars in JVAS/CLASS surveys
- Dipole Modulation of Cosmic Microwave Background Temperature and Polarization
- Polarization Alignment in JVAS/CLASS flat spectrum radio surveys
- Relating the inhomogeneous power spectrum to the CMB hemispherical anisotropy
- Imprint of Inhomogeneous and Anisotropic Primordial Power Spectrum on CMB Polarization
- Mapping the dark matter with polarized radio surveys
- Effect of Foregrounds on the CMBR Multipole Alignment
- Extracting Spectral Index of Intergalactic Magnetic Field from Radio Polarizations
- Noncommutative Geometry and the Primordial Dipolar Imaginary Power Spectrum
- Cosmological Power Spectrum in Non-commutative Space-time
- Interpretation of the Global Anisotropy in the Radio Polarizations of Cosmologically Distant Sources
- Testing the Alignment Tendency of Some Polarized Radio Sources
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- Testing the standard model of cosmology with the SKA: the cosmic radio dipole
- Theoretical systematics in testing the Cosmological Principle with the kinematic quasar dipole
- The scale of homogeneity in the local Universe with the ALFALFA catalogue
- The angular scale of homogeneity in the Local Universe with the SDSS blue galaxies
- Joint Bayesian analysis of large angular scale CMB temperature anomalies
- New evidence and analysis of cosmological-scale asymmetry in galaxy spin directions
- Using 3D and 2D analysis for analyzing large-scale asymmetry in galaxy spin directions
- Local patch analysis for testing statistical isotropy of the Planck convergence map
- A study of Dipolar Signal in distant Quasars with various observables
- A Pixel Space Method for Testing Dipole Modulation in the CMB Polarization
- A comprehensive study of Modulation effects on CMB Polarization