As you want to become a cosmologist so for it you have to do graduation in Avionics & Aerospace engineering, bcoz Cosmologists utilize ground based and space borne telescopes to reveal the facts of and get information on different properties of celestial bodies, for example, movement, physical properties, separation, size and other important things.

Duties of cosmologist
Cosmologist Analyze the data which is obtained using those telescopes.
They create theories and perform test on those to identify the origin of astronomical bodies and the universe.
Cosmologist also help in designing the scientific instruments which is used in the cosmology like telescopes and laser.
They also help in developing software to analyze data.

Colleges from where you can study related to Cosmologist
India Institutes of Space Science and Technology, Trivandrum
Indian Institute of Astrophysics, Bangalore
Tata Institute of Fundamental Research, Pune
Raman Research Institute, Bangalore
Physical Research laboratory, Ahmedabad
Indian Institute of Sciences, Bangalore

After study you can do job as Cosmologist in following organization
Space research organizations
Physical laboratories
Aerospace companies
Planetariums
Colleges and Universities teaching astronomy and cosmology
Observatories
Astronomical equipment manufacturers
NGOs and space application centers