Interstellar Scattering of the VELA Pulsar

AbstractObservations of speckles in the scattering disk of the Vela pulsar are presented and speckle techniques for studying and circumventing scattering of radio waves by the turbulent interstellar plasma are discussed. The speckle pattern contains, in a hologrammatic fashion, complete information on the structure of the radio source as well as the distribution of the scattering material. Speckle observations of interstellar scattering of radio waves are difficult because of their characteristically short timescales (≈seconds) and narrow bandwidths (≈kHz). Here, we present first observations, taken at 13 cm wavelength with elements of the SHEVE VLBI network, of speckles in interstellar scattering.

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Interstellar Scattering and the Pulse from the Vela Pulsar

Symposium - International Astronomical Union ◽

10.1017/s0074180900007476 ◽

1971 ◽

Vol 46 ◽

pp. 217-221

Author(s):

M. M. Komesaroff ◽

P. A. Hamilton ◽

J. G. Ables

Keyword(s):

Interstellar Medium ◽

Wavelength Range ◽

Fourth Power ◽

Magnetic Pole ◽

Rotation Measure ◽

Interstellar Scattering ◽

Vela Pulsar ◽

Multipath Scattering ◽

Pulse Broadening

Measurements of PSR 0833 − 45 were made at wavelengths of 21, 48, 73 and 100 cm. Pulse broadening proportional to about the fourth power of the wavelength was found, consistent with multipath scattering in the interstellar medium. It is further concluded that the rotation measure was constant at 33.2 rad m−2 across this wavelength range, supporting the conclusion that the radiation originates in the vicinity of a magnetic pole.

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Two-component model for the interstellar scattering in direction to the Vela pulsar

Astronomy and Astrophysics ◽

10.1051/0004-6361:20042625 ◽

2005 ◽

Vol 438 (3) ◽

pp. 909-914 ◽

Cited By ~ 3

Author(s):

A. Z. Zhou ◽

A. Esamdin ◽

X. J. Wu

Keyword(s):

Component Model ◽

Two Component ◽

Interstellar Scattering ◽

Vela Pulsar

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Southern Hemisphere Seti Survey: Five Years of Project Meta II

International Astronomical Union Colloquium ◽

10.1017/s0252921100015153 ◽

1997 ◽

Vol 161 ◽

pp. 611-621

Author(s):

Guillermo A. Lemarchand ◽

Fernando R. Colomb ◽

E. Eduardo Hurrell ◽

Juan Carlos Olalde

Keyword(s):

Southern Hemisphere ◽

Scattering Theory ◽

Galactic Plane ◽

Narrow Band ◽

Neutral Hydrogen ◽

Sky Survey ◽

Inertial Frames ◽

Interstellar Scattering ◽

Extraterrestrial Origin ◽

Spectral Channels

AbstractProject META II, a full sky survey for artificial narrow-band signals, has been conducted from one of the two 30-m radiotelescopes of the Instituto Argentino de Radioastronomía (IAR). The search was performed near the 1420 Mhz line of neutral hydrogen, using a 8.4 million channels Fourier spectrometer of 0.05 Hz resolution and 400 kHz instantaneous bandwidth. The observing frequency was corrected both for motions with respect to three astronomical inertial frames, and for the effect of Earths rotation, which provides a characteristic changing signature for narrow-band signals of extraterrestrial origin. Among the 2 × 1013spectral channels analyzed, 29 extra-statistical narrow-band events were found, exceeding the average threshold of 1.7 × 10−23Wm−2. The strongest signals that survive culling for terrestrial interference lie in or near the galactic plane. A description of the project META II observing scheme and results is made as well as the possible interpretation of the results using the Cordes-Lazio-Sagan model based in interstellar scattering theory.

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Angular velocity glitches of the Vela pulsar in a model with “centrifugal buoyancy” of vortices

Astrophysics ◽

10.1007/s10511-007-0015-9 ◽

2007 ◽

Vol 50 (2) ◽

pp. 144-156 ◽

Cited By ~ 1

Author(s):

D. M. Sedrakian ◽

M. V. Hayrapetyan ◽

L. R. Sedrakian

Keyword(s):

Angular Velocity ◽

Vela Pulsar

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A Search for Very Compact Structure in 17 OH Masers

Symposium - International Astronomical Union ◽

10.1017/s0074180900134618 ◽

1988 ◽

Vol 129 ◽

pp. 255-256

Author(s):

A. J. Kemball ◽

P. J. Diamond ◽

F. Mantovani

Keyword(s):

Galactic Disk ◽

Hii Regions ◽

Scale Structure ◽

Small Scale ◽

Compact Structure ◽

Small Scale Structure ◽

Interstellar Scattering

The apparent spot sizes of OH masers appear to be significantly broadened when seen through the inner galaxy or large extents of the galactic disk (Burke 1968). Bowers et al (1980) found evidence of small-scale structure (≲ 50 mas) in OH sources at distances of less than 5 kpc but this was characteristically absent in very distant sources (≳ 8kpc) at galactic longitudes 1 ≲ 40°. This result is typically explained in terms of interstellar scattering (ISS) by intervening diffuse HII regions.

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