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

Astronomy & Astrophysics 53 have been studied. These studies indicate 12 - 20M progenitors in type IIP supernovae,Wolf-Rayet progenitors (20 - ʘ 25M ) in the case of Ib/c supernovae, while the study of the type Ib supernova iPTF13bvn provided the first evidence ʘ of a binary progenitor in type Ib supernovae. The study of optical and radio afterglows of GRBs during the past two decades has benefited greatly by the longitudinal advantage of Indian sub-continent. Beginning with the first ever afterglow detection for a GRB in 1999, GRB 990123, well-calibrated photometric and spectroscopic data observed using Indian optical-NIR facilities and the GMRT clubbed alongwith data obtainedwith other collaborative facilities have been employed to constrain the nature and underlying physics of many of these energetic stellar explosions. These studies have helped us to contribute towards deciphering the jet geometry, nature of possible progenitors and their ambient media, etc. Multi-wavelength observations using Indian facilitates of bursts like GRB 201004, GRB 021211 have shown the presence of diversity in these events. Extensive studies of some of the rare GRBs associated with underlying broad-lined type Ic SNe (e.g GRB 0303029/SN 2003dh) using optical and radio telescopes and have helped to constrain not only the non-thermal synchrotron afterglow models but also helped in understanding the properties of the underlying SNe indicating towards collapse of a massive star as possible progenitor. On-board high energy instruments of AstroSat have also observed temporal, spectral and polarimetric properties of a few hundred of GRBs which have greatly helped to improve our understanding about prompt emission properties of GRBs including magnetic field structure within the jet and shock physics. Polarisation has been detected in many GRBs observed using AstroSat-CZTI. Spectropolarimetric studies of the prompt emission of GRBs using X-ray and ɤ-ray data may provide clues to understand their physical origin better. Indian astronomers are contributing significantly in the study of fast transients through national and international collaborations. Based on long term multi-wavelength monitoring, FBOTs AT2018cow and AT2020xnd were studied in detail and it was shown that the multi-wavelength behaviour of these objects is consistent with the model of an accretion powered jet following the direct collapse of a massive star to a black hole. Indian astronomers are collaborating in the international Canadian Hydrogen Intensity Mapping Experiment (CHIME) project, through which over 500 FRBs were detected and it was shown that these sources have a uniform distribution in the sky. In a recent uGMRT observing campaign of FRB 180916.J0158+65, it was shown that this source has a 16.35-d periodicity of its active cycle. Analysis pipeline for detecting transients in the radio wavelengths are being developed for the upgraded Ooty radio telescope. Observations of some of these transients exhibiting lensed character can be used to put constraints on cosmological parameters and to improve lens models.While theoretical studies were done in this area in the past, recent studies include observational aspects as well with increasing number of transients. 4.1.14 Compact Objects Compact objects include white dwarfs, neutron stars, and stellar-mass and super-massive black holes. These exotic objects are nature's laboratories to study physics at extreme conditions, e.g., densities, temperature, magnetic field, gravitational acceleration significantly higher than what could be produced in our laboratories. Groups in many different institutions have worked on these objects from a very diverse set of perspectives. Indian scientists have made very significant contributions to the understanding of the structure and evolution of compact stellar remnants like neutron stars and black holes. Modelling of compact objects with accretion of gas and related phenomena using theoretical and computational approaches is being pursued by several groups. MEGA SCIENCE VISION-2035