Journey of X-ray astronomy: Indian perspectives

X-ray astronomy is a mature area of observational astronomy. After the discovery of the first non-solar X-ray source in 1962, X-ray astronomy proliferated during the Apollo era's space race. Then, it matured as an established area of research during the period of Great Observatories, and now it has become an indispensable tool to understand a wide variety of astrophysical phenomena. Consequently, in recent times, niche observational areas in X-ray astronomy have been explored, and attempts have been made to expand the sensitivity of observations vastly. India was an active partner in the growth of X-ray astronomy. In the initial years, India leveraged its expertise in balloon technology to get significant results in the research area of hard X-ray astronomy. During the rapid growth phase of X-ray astronomy, India made divergent all-round efforts. Later on, however, the technical expertise available in India was insufficient to compete with the highly sophisticated satellite experiments from around the world. During this phase, work in X-ray astronomy continued in a few low-key experiments, eventually resulting in the launch of India's first multi-wavelength astronomical satellite, AstroSat, in 2015. In this article, I will trace the journey of X-ray astronomy and the developments in the Indian context. I will also explore the sociological aspects of the growth of X-ray astronomy, and, in the end, I will present a speculative sketch of the future of X-ray astronomy with an emphasis on the Indian contribution.