The Epoch of Reionization: Foregrounds and calibration with PAPER

Daniel C Jacobs, University of Pennsylvania


Over the last 20 years we have learned that the contents of the universe are spit into 76% Dark Energy and 24% Matter, 17% of which is ordinary matter. Of the ordinary matter the bulk is hydrogen which forms the raw material for building stars. The universe began 14 Billion years ago with an expanding space-time and quickly began After about 300,000 years this all cooled enough for the plasma to recombine into neutral hydrogen gas and release photons which we eventually observe redshifted into the radio; the Cosmic Microwave Background (CMB). Nearly half a billion years passed before the slow process of gravitational collapse would lead to the formation of the first galaxies and the (re) ionization of the ubiquitous hydrogen. This Epoch of Reionization (EoR) is the next major unexplored cosmological milestone. At the current time the space between galaxies is almost completely ionized, therefor we know that the universe must have undergone a global phase transition. The nature of the ionizing sources, whether young galaxies or accreting massive black holes is unknown. Neither do we know when this reionization occured or how long it took. Models suggest that we can detect fluctuations in the 21cm hydrogen emission line as ionization proceeds and high contrast ionized holes are carved in the neutral hydrogen. Detecting these fluctuations is one of the few direct probes of the reionization process but is a difficult task requiring a new generation of low frequency radio telescopes. Motivated by the breadth of unknowns, the Precision Array for Probing the Epoch of Reionization (PAPER) has been slowly building in complexity while folding the results of observations back into improving the design and operation of the telescope. As part of this process, this thesis analyzes early observations to explore three major areas of concern in detecting EoR: contamination by foreground sources, calibration stability and limiting sensitivity. Catalogs produced from this early data show good agreement with previous measurements. We conclude that the calibration is stable and sensitivity floors are close to the expected theoretical levels.

Subject Area


Recommended Citation

Jacobs, Daniel C, "The Epoch of Reionization: Foregrounds and calibration with PAPER" (2011). Dissertations available from ProQuest. AAI3485704.