Dr. Jasjeet Bagla
Professor , Physical Sciences

Email jasjeet(AT)iisermohali.ac.in
Phone +91 172 2293130
Fax +91 172 2240266
Personal Page Dr. Jasjeet Page                                                              
ORCID ID 0000-0002-7749-4155
Research Area
Astrophysics, Cosmology
Research Focus

I work on questions related formation of galaxies and large scale structure within the framework of the standard cosmological model. It is believed that the large scale structure forms due to gravitational collapse around over dense regions. This process amplifies tiny fluctuations in density and leads to formation of highly over dense regions called halos. Galaxies are believed to form when gas in halos cools and undergoes further collapse to form stars.

The process of gravitational collapse in an expanding universe is fairly complex and we are required to simulate this on super computers in order to follow relevant details. My contribution in this field has been in development of highly optimized methods for doing cosmological N-Body simulations. We have used these simulations to study the process of gravitational clustering and demonstrate that this process erases differences between different types of initial fluctuations. Suites of simulations have also been used to point out deviations from certain strong assumptions made in approximate methods.

Computer simulations of galaxy formation allow us to develop strategies for observations that require a large amount of time. We have used simulations to propose efficient ways to detect galaxies using emission in the hyperfine transition of neutral Hydrogen at high redshifts. Contrary to the received wisdom, we were able to demonstrate that direct detection may be easier than a statistical detection of the large scale structure.

I also work on new probes of the high redshift universe. We have shown that the hyperfine transition in singly ionized Helium-3 is a potential probe of the inter-galactic medium. Efforts are underway to observe certain promising regions in the inter-galactic medium at high redshifts.

Selected Publications

  • Bagla J. S. and Padmanabhan T. 1994, MNRAS 266, 227: Nonlinear Evolution of Density Perturbations using approximate constancy of Gravitational Potential.
  • Bagla J. S. 1998, MNRAS 299, 417: Evolution of Galaxy Clustering.
  • Bagla J. S. 2002, Journal of Astrophysics and Astronomy 23, 185: TreePM: A code for Cosmological N-Body Simulations.
  • Bagla J. S., Jassal H. K. and Padmanabhan T. 2003, Phys.Rev.D 67, 063504: Cosmology with tachyon field as dark energy.
  • Bagla J. S. and Prasad Jayanti 2006, MNRAS 370, 993: Effects of the size of cosmological N-Body simulations on physical quantities - I: Mass Function.