TY - JOUR
T1 - Probing Statistical Isotropy of Cosmological Radio Sources using Square Kilometre Array
AU - Ghosh, Shamik
AU - Jain, Pankaj
AU - Kashyap, Gopal
AU - Kothari, Rahul
AU - Nadkarni-Ghosh, Sharvari
AU - Tiwari, Prabhakar
N1 - Publisher Copyright:
© 2016, Indian Academy of Sciences.
PY - 2016/12/1
Y1 - 2016/12/1
N2 - 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.
AB - 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.
KW - Square kilometre array
KW - cosmological principal
KW - intrinsic dipole
KW - kinematic dipole
UR - http://www.scopus.com/inward/record.url?scp=84988662711&partnerID=8YFLogxK
U2 - 10.1007/s12036-016-9395-8
DO - 10.1007/s12036-016-9395-8
M3 - 文献综述
AN - SCOPUS:84988662711
SN - 0250-6335
VL - 37
JO - Journal of Astrophysics and Astronomy
JF - Journal of Astrophysics and Astronomy
IS - 4
M1 - 25
ER -