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Title: Cyclic spectroscopy of the millisecond pulsar, B1937+21

Cyclic spectroscopy is a signal processing technique that was originally developed for engineering applications and has recently been introduced into the field of pulsar astronomy. It is a powerful technique with many attractive features, not least of which is the explicit rendering of information about the relative phases in any filtering imposed on the signal, thus making holography a more straightforward proposition. Here we present methods for determining optimum estimates of both the filter itself and the statistics of the unfiltered signal, starting from a measured cyclic spectrum. In the context of radio pulsars these quantities tell us the impulse response of the interstellar medium (ISM) and the intrinsic pulse profile. We demonstrate our techniques by application to 428 MHz Arecibo data on the millisecond pulsar B1937+21, obtaining the pulse profile free from the effects of interstellar scattering. As expected, the intrinsic profile exhibits main- and inter-pulse components that are narrower than they appear in the scattered profile; it also manifests some weak, but sharp, features that are revealed for the first time at low frequency. We determine the structure of the received electric field envelope as a function of delay and Doppler shift. Our delay Doppler image has amore » high dynamic range and displays some pronounced, low-level power concentrations at large delays. These concentrations imply strong clumpiness in the ionized ISM, on AU-size scales, which must adversely affect the timing of B1937+21.« less
Authors:
 [1] ;  [2] ;  [3]
  1. Manly Astrophysics, 3/22 Cliff Street, Manly 2095 (Australia)
  2. National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States)
  3. Swinburne University of Technology, Astrophysics and Supercomputing, Hawthorn 3122 (Australia)
Publication Date:
OSTI Identifier:
22348482
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 779; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABUNDANCE; ASTRONOMY; COSMOLOGY; DATA ANALYSIS; DOPPLER EFFECT; ELECTRIC FIELDS; MHZ RANGE; PULSARS; SCATTERING; SPECTRA; SPECTROSCOPY; STARS