AR-2020-21

262 33 rd ANNUAL REPORT 2020-21 Department of Physics and Astrophysics, University of Delhi (Coordinator: T.R. Seshadri) Areas of Research · Astrophysical and Cosmological Magnetic Fields · Fast Radio Bursts · Modified Theories of Gravity and their Cosmological Implications · Late Time Acceleration of the Universe · Study of Carbonaceous Aerosols in the Atmosphere in Central Himalayas The combined effect of a non-standard baryon dark matter interaction has been investigated. It has been shown that the y-parameter of the CMB can be significantly enhanced in the presence of both these effects (ArunK. Pandey, Sunil Malik, andT.R. Seshadri). The data that has been obtained through an observational proposal to VLAto study cluster magnetic fields is being continued (Sunil Malik, Venkateshh Ramakrishnan, Ruta Kale, Hum Chand, Bidisha Bandyopadyay, andT.R. Seshadri) It is shown that the evolution of baryon temperature and ionization fraction get modified due to the presence of helical magnetic fields. These in turn lead to modifications in the CMB temperature and polarization anisotropy (Sandhya Jagannathan, Ramkishor Sharma, andT.R. Seshadri). To constrain galaxy parameters and cosmic curvature, the distance ratio data from a recently compiled database of 161 galactic scale strong lensing systems modelled as an extended power-law have been used. Further, using time-delay measurements and distance sum rule, constraints have been placed on the curvature parameters (Darshan Kumar, Deepak Jain, Shobhit Mahajan, Amitabha Mukherjee, and Nisha Rani). A systematic statistical analysis has been carried out to study the correlations among various physical quantities associated with the FRBs belonging to the different categories (Nidhi Saini, and Patrick D. Gupta). The possibility of f(R) models to the observed accelerated expansion of the Universe is being investigated. In particular, generation of cosmology with a bounce using such models is being studied (Manjeet Kaur, Debajyoyi Choudhury, andT.R. Seshadri).