Probing Statistical Isotropy of Cosmological Radio Sources using Square Kilometre Array

Shamik Ghosh, Pankaj Jain*, Gopal Kashyap, Rahul Kothari, Sharvari Nadkarni-Ghosh, Prabhakar Tiwari

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

12 Scopus citations


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 the 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 (CMB) 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.

Original languageEnglish
Article number25
JournalJournal of Astrophysics and Astronomy
Issue number4
StatePublished - 1 Dec 2016
Externally publishedYes


  • Square kilometre array
  • cosmological principal
  • intrinsic dipole
  • kinematic dipole


Dive into the research topics of 'Probing Statistical Isotropy of Cosmological Radio Sources using Square Kilometre Array'. Together they form a unique fingerprint.

Cite this