Type of Document Master's Thesis Author Wilson, Derek Edwin Author's Email Address firstname.lastname@example.org 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 Keywords
- digital signal processing
- radio astronomy
- astronomical transients
Date of Defense 2005-08-23 Availability unrestricted AbstractDispersed 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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