Discuss how multi-wavelength, multi-messenger astronomy is reshaping our understanding of transient cosmic events. Illustrate with recent Indian contributions.

Transient cosmic events — gamma-ray bursts, neutron-star mergers and the newly recognised Fast X-ray Transients (FXTs) — are brief flashes lasting minutes to hours, too short for any single telescope to decode [1]. Multi-wavelength (radio to X-ray) and multi-messenger (light plus gravitational waves) observation has therefore become the decisive method for identifying what powers them.

How the approach reshapes understanding

• Identifying progenitors: a single X-ray detection reveals only a flash; combined radio, optical and X-ray follow-up of FXT EP241107a allowed astronomers to trace it to either a massive-star collapse (collapsar) or a binary neutron-star merger [1][2].
• Revealing hidden explosions: EP241107a was interpreted as an "orphan afterglow" — a gamma-ray-burst-like blast whose gamma rays missed Earth, detectable only through its later afterglow across other wavelengths [2].
• Measuring extreme physics: the event's kinetic energy was comparable to the entire Milky Way's light output over several months, quantifiable only by combining bands [2].
• Time-domain rapid response: China's Einstein Probe (2024) now detects such events routinely, but origin-fixing requires coordinated global follow-up within hours [2].

Recent Indian contributions

• The study was led by the Indian Institute of Astrophysics (IIA), Bengaluru, an autonomous institute under the Department of Science & Technology, and published in the Monthly Notices of the Royal Astronomical Society [1][2].
• Indian facilities anchored the follow-up: the Himalayan Chandra Telescope at Hanle, Ladakh, the GROWTH-India Telescope (IIA–IIT Bombay) and the upgraded GMRT (NCRA-TIFR), alongside the VLA, Keck and SOAR [2].
• The radio counterpart — the clinching evidence — was found using the Karl G. Jansky Very Large Array by the Indian-led team [1].

Multi-messenger astronomy has thus converted transients from unexplained flashes into measurable laboratories of extreme physics. India's high-altitude observatories, DST-funded institutions and international data-sharing position it as a credible node in this global network; sustaining investment in time-domain facilities and gravitational-wave capability will convert participation into leadership.