Title page for ETD etd-08232005-212614

Type of Document Master's Thesis
Author Wilson, Derek Edwin
Author's Email Address dewilso4@vt.edu
URN etd-08232005-212614
Title A Pilot Survey for Astronomical Low Frequency Radio Transients
Degree Master of Science
Department Electrical and Computer Engineering
Advisory Committee
Advisor Name Title
Ellingson, Steven W. Committee Chair
Brown, Gary S. Committee Member
Reed, Jeffrey Hugh Committee Member
  • digital signal processing
  • radio astronomy
  • astronomical transients
Date of Defense 2005-08-23
Availability unrestricted
Dispersed low-frequency radio astronomical pulses may result from exploding primordial

black holes, gamma ray bursts, supernovae, or mergers of exotic objects, but have not yet

been detected. Detection would be of great scientific significance because such events must

involve extreme physics. The transient nature of these events makes detection unlikely with

traditional instruments due to lack of sensitivity to single pulses and narrow field of view.

For this thesis, a low-frequency wide-bandwidth astronomical search instrument has been

developed as an alternative approach. This instrument consists of a single dipole which

yields all-sky field of view, albeit at reduced sensitivity. The spectrum from 37 - 55 MHz

is coherently digitized at 200 million samples per second, recorded, and analyzed off-line for

the presence of dispersed pulses. A preliminary survey has been made at a remote site in

western North Carolina. In a 20 minute observation, 9 detections greater than 6.5 occurred, corresponding to pulses of  20 ms duration and dispersion measures (DMs) ranging from 15 to 70 pc cm−3 . In addition, groups of pulses were detected ( 5) at DMs of 43.1, 52.1,

and 52.2 pc cm−3 . The possibility of association with known pulsars is considered; however,

it is also possible these are due simply to radio frequency interference. Improvements to this

instrument and survey technique are suggested.

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