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

Astronomy & Astrophysics 57 gained momentum in 1990s and first detection of signal was made in 2015. Gravitational waves from astrophysical events create extremely weak signals, even in the present kilometre-scale state-of-the-art detectors. The signal is buried deep in noise and sophisticated analysis strategies, based on advanced mathematical techniques, are used to detect the signal. Indian scientists have played leading roles in establishing and advancing these techniques. Very detailed analytical calculations to predict the expected waveform from an inspiralling binary of compact objects have been developed and improved over the last four decades. Indian researchers are involved in frontier research in Numerical Relativity to model these waveforms using supercomputers. Development of large computing facilities is also ramping up in the country for these purposes. GW observations provide a robust way to test Einstein's theory of General Relativity in the strong field regime, near black holes. Indian researchers have significantly contributed to develop schemes to conduct these tests, which will become far more accurate as the sensitivities of the detectors improve and space-based detectors are launched. In view of LIGO-India, huge amount of activities have started in the country in instrumentation and detector characterisation for GWobservatories. Gravitational waves in a binary merger can, in principle, arise from the merger of a wide variety of components and it takes a number of parameters to completely specify such a system. Binary systems containing a neutron star, or core- collapses of massive stars, are expected to be associated with transient like gamma-ray bursts, kilonovae, and supernovae. The search for these electromagnetic (EM) counterparts poses both observational and data-analysis challenges. Large regions of the sky need to be covered for these searches, that require the removal of contaminating transients not related to the gravitational-wave source for the identification of the unique transient counterpart. Indian scientists have contributed crucial ideas to optimize this search and also implemented these ideas in programs that have been used by international collaborations. As members of global collaborations engaged in the search for EM counterparts, scientists from India contributed to the observations of the first (and only) EM counterpart detected for a GW source – GW 170817, that was a result of a binary neutron star merger. The observations using the GMRT, in particular, were crucial in confirming some of the models proposed to explain the nature and evolution of the kilonova associatedwith this merger event, also observed as a short durationGRB. MEGA SCIENCE VISION-2035 4.2 Observing Facilities This section summarises the present status and future proposed upgrades of the various operating astronomical facilities in the country. 4.2.1 RadioAstronomy At present India has some very good facilities specialising in low frequency radio astronomy. Perhaps the oldest of these is the Ooty Radio Telescope (ORT), operational since 1970, which is a large cylindrical paraboloid 500-meter long operating at a frequency of 325MHz. The ORT, built and operated by NCRA, the radio astronomy group of TIFR, has been used extensively over five decades for a range of studies covering interplanetary medium and space weather, pulsars, interstellar medium, extragalactic astronomy and cosmology. The ORT is currently undergoing a major receiver upgrade, which will result in a new system called the OotyWide FieldArray (OWFA). The OWFAis designed to function as a 264-element interferometric array, and to provide a significantly larger instantaneous bandwidth as well as field-of-view compared to the legacy ORT receiver system. In addition to significantly enhancing ORT's