AR_final file_2018-19

MAGNETIC FIELD Galaxies consist of dark matter and gas, where some of the gas condenses to form stars. The diffuse gas inhabiting the space between stars exists in the form of a partially ionised plasma. One ubiquitous entity that threads through all this gas is a magnetic field, whichis present everywhere in the universe at varying strengths. The origin of these magnetic fields continues to remain an unsolved mystery. Scientists at IUCAA, while exploring a popular mechanism called the Dynamo, have discovered that this operates on two different scales. The process is at first driven at small scales by turbulent motion of gas and as that saturates, the large scale differential motion of gas takes over to amplify the field manifold. The Dynamo mechanism is in fact an amplification process, the success of which depends on the existence of an initial seed field, however weak. Some say that the seed field originated in the very early universe, during a phase of rapid expansion called the Inflation. Scientists at IUCAA have demonstrated that such an origin will be accompanied by the generation of Gravitational Waves that would be detectable by the future generation of instruments. Magnetic fields play a key role in the dynamics of the outer layers of the Sun, especially the chromosphere and the Corona. Sunspots and solar active regions harbour very strong magnetic fields. Research at IUCAA has uncovered the role of inclined magnetic fields in the transport of energy from the lower to the upper layers of the solar atmosphere. Waves of millihertz frequency travelling along these field lines are seen to be responsible for this energy transfer. This may help explain why the outermost parts of the solar atmosphere, namely the corona, can stay much hotter than the solar surface. ( 40 )