Research with LOFAR is organized into a number of ‘Key Science Projects’ (KSPs) that address particular scientific themes. The LOFAR KSPs are independently organized international research groups which are required to make recognized contributions to the development of LOFAR and its scientific output. Astrophysics groups in Ireland are also part of these international KSPs, a selection of which are listed below.
Following the Big Bang, a period of the Universe’s history probed extensively over the past couple of decades by cosmic microwave background experiments, sub-atomic particles combined together to form neutral hydrogen. The first stars in the early universe formed from this neutral environment. Once these stars ignited, they flooded the Universe with light, leading to the ionization of this surrounding neutral environment. This is known as the Epoch of Reionization (EoR, see image below), leading the Universe out of its ‘dark-ages’ and to the birth of the first stars to come into existence. Exactly when and how this reionization occurred is one of the great unanswered questions in modern cosmology and studying the EoR has been one of the key drivers for the design of LOFAR, the measurements from which could have fundamental implications for astrophysics and theories of the Universe’s formation.
2. All-sky Surveys
The sensitivity and extremely large field-of-view of LOFAR make it an ideal instrument for undertaking deep, large area surveys. LOFAR will produce a series of unique surveys of the low-frequency radio sky, which will open a new window on numerous fundamental areas of astrophysics. Notable amongst these are: formation of massive galaxies, clusters and black holes using z ≥ 6 radio galaxies as probes; Intercluster magnetic ﬁelds using diffuse radio emission in galaxy clusters as probes, and; Star formation processes in the early Universe using starburst galaxies as probes. The Surveys KSP will be optimized for obtaining large samples of radio objects in these and other categories, such as the objects in the LOFAR image below. These objects will be studied individually and also collectively for precision statistical analysis. A number of all-sky, multi-frequency surveys are planned over multiple epochs, also enabling variable sources to be recognized.
3. Transients Sources
Our universe can be a violent and rapidly changing place. Exploding stellar giants, accreting supermassive black holes, rapidly rotating superdense neutron stars, can all release enormous energies into their surrounding environments on very short timescales, acting as cosmic thermostats, keeping the environment in an active state, triggering star formation and regulating the growth of galaxies. In nearly all cases, such events and phenomena have associated radio emission, so by observing in the radio band we can understand where and how often such events occur, and gauge their combined impact on the ambient environment. The LOFAR Transients KSP focusses on exploring and understanding the explosive and dynamic universe by observing transient and variable radio sources. Thanks to the enormous field of view and multiple beams of LOFAR, for the first time we will be able to monitor a large fraction of the sky on a regular basis, allowing us to make an accurate census of such sources.