MSV-2035 Astronomy Document - Inside Design - FINAL - FINAL

Astronomy & Astrophysics 48 functions, semi-analytical models and approximations, and cosmological N-Body simulations. Indian astronomers have contributed to all aspects in this area with significant ideas that have been adopted by research groups all over the world. One idea that has been around for some time is that the presence of large scale magnetic fields in the Universe can influence the evolution of large scale structure and galaxy formation. This is an interesting possibility that needs to be explored as magnetic fields are the only other long range force other than gravity in a Universe that is charge neutral at large scales. This possibility has been explored in detail by Indian scientists and they have put strong upper limits on the possible strength of large scalemagnetic field. Observations of galaxies can also be used to test some of the basic assumptions of large scale homogeneity used in constructing cosmological models. Indian astronomers have used fractal measures to test this assumption and estimate the scale of homogeneity. Theoretical work relating fractal dimensions with the correlation function has also been used to connect two approaches that were considered disparate. Lastly, a new definition of the scale of homogeneity has been suggested that is based on inability to distinguish between the distribution of galaxies and a random distribution of points. Understanding the large scale distribution of galaxies through halo models is yet another area with significant contributions. This approach is also useful to study the distributions of ionised bubbles during reionisation etc. Figure 6: Distribution of SDSS galaxies in the direction of the Pisces constellation. The central high density of galaxies is the Saraswati supercluster region (enlarged in the inset). Note that each point corresponds to a galaxy, and the typical size of a galaxy here is around 250,000 light years. Figure Source: IUCAA (adapted from Bagchi et al. 2017, ApJ 844, 25). MEGA SCIENCE VISION-2035