Short-term explosive phenomena are often another signpost for extreme astrophysics, signalling formation of black holes and neutron stars, or later energetic outbursts from them. API faculty use time domain astronomy from gamma rays to radio waves, and other messengers such as gravitational waves and TeV gamma rays, to probe such transients, and try to piece together fundamental understanding of them via complex modelling
Transient sources are very often caused by highly energetic types of event that are physically associated with black holes and neutron stars, as they are born and later as they evolve while interacting with matter around them. As such they are very good signposts towards extreme physical phenomena in the Universe.
API researchers played a leading role in the discovery and early characterization of two new types of transient phenomena. The first of these is the detection of gravitational waves by LIGO/Virgo, and the observational effort to detect their driving sources (the 'electromagnetic counterpart'), heralding the 'dawn of multi-messenger astronomy'. Another newly discovered phenomenon are fast radio bursts, whose nature remains mysterious. Furthermore, advances were made in the study of cosmic radiation and supernova remnants, and instrumentation development for the HESS telescope. LOFAR and AARTFAAC are now coming into their own as discovery machines for rare and/or peculiar transients.
Now: Swift, Chandra, XMM-NEWTON, LOFAR, WHT, VLT, LVC, MeerKAT, Apertif, large-scale computing
Future: BlackGEM/MeerLICHT, LOFAR2.0, SKA, E-ELT, ATHENA, CTA, transient survey machines