The LOFAR epoch of reionization experiment data model: simulations, calibration and inversion

PhD ceremony: Mr. P. Lampropoulos, 11.00 uur, Academiegebouw, Broerstraat 5, Groningen

Thesis: The LOFAR epoch of reionization experiment data model: simulations, calibration and inversion

Promotor(s): prof. L.V.E. Koopmans, prof. S. Zaroubi, prof. A.G. de Bruijn

Faculty: Mathematics and Natural Sciences

One of the most exciting applications of LOFAR will be the search for redshifted 21 cm line emission from the Epoch of Reionisation (EoR). The thesis of Panagiotis Lampropoulos examines the relationship between the sky signal and the observed data and discusses a statistically optimal solution for the processing of LOFAR data, that is also computationally efficient.

It is currently believed that the Dark Ages, the period after recombination when the Universe turned neutral, lasted until around the Universe was 400,000 years old. During the EoR, objects started to form in the early universe and they were energetic enough to ionize neutral hydrogen. The most prominent method to unravel the string leading to this epoch is the 21-cm line of neutral hydrogen, the most abundant element in the Universe. Due to the expansion of the Universe, this line is redshifted to the low regime of the radio spectrum with wavelengths of the order of a few meters. The sensitivity required to achieve this scientific goal, essentially translates into accumulating large amounts of data. Furthermore, the data have to be corrected for instrumental and atmospheric distortions to an unprecedented level.