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An Autonomous Institution, Ministry of Education, Govt. of India
Seminars and Colloquia


The Large-scale Structure of our Universe with Radio galaxies 
Wed, Mar 20, 2019,   04:00 PM at Seminar Hall 31, 2nd Floor, Main Building

Dr Prabhakar Tiwari
NAOC, Beijing

The observable Universe is simply huge! $\\sim10^{26}$ meters in every direction, $\\sim14$ billion years old and contains $\\sim10^{80}$ hydrogen atoms. The modern cosmology is the science of the entire Universe.  We, here on a small planet, can only assume that the Universe is knowable and physics is followed everywhere in the same manner. Furthermore it is reasonable to assume that the observable Universe is statistically same for all observers, located anywhere in the Universe.
Today, we demand this uniformity as ``Cosmological Principle'' which assumes homogeneity and isotropy at large distance scales. This is a fundamental assumption in our standard cosmological framework and therefore must be tested explicitly by observations. In this talk, I will present some great (bizarre, famous, significant!) observations of large scale isotropy/anisotropy achieved by employing radio galaxy surveys. In particular I will discuss radio galaxy number count dipole and the latest  dipole–quadruple–octopole alignment results from NVSS+SUMSS. I will review a few more observations  of large scale isotropy/anisotropy and discuss some existing theoretical proposals to explain these.    At present there are several major radio galaxy observations available e.g. LOFAR surveys, TGSS, GLEAM, LoTSS etc. and we have a lot to explore from these observations, later on  we are going to have Square Kilometre Array (SKA) observations. 
With SKA all radio physics is going to benefit immensely, I will discuss how much improvement we are going to have on isotropy/anisotropy observations with SKA.