The shape of pulsar radio beams

Lyne, A. G.; Manchester, R. N.

doi:10.1093/mnras/234.3.477

Cited by 610 publications

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“…Using the above results, published values for pulsar geometries (Lyne & Manchester 1988, Rankin 1993b, and assuming circular beams, we calculated p corresponding to the 10%-intensity width (see Gil et al 1984. In accordance with the results of Rankin (1993a) and Gil et al (1993), we find that opening angles are generally located on two lines if they are plotted versus period in a log-log diagram.…”

Section: Results and Conclusionmentioning

confidence: 99%

“…One generally distinguishes between core and conal components, although it is yet unclear whether core and conal components originate from the same (Lyne & Manchester 1988) or a different emission mechanism (Rankin 1983). Investigating this problem, we studied the behaviour of individual components observed in about 200 profiles of 18 pulsars measured at three different frequencies, i.e.…”

Section: Introductionmentioning

confidence: 99%

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Separation of integrated pulse shapes into unique sub-components

Krämer

1996

International Astronomical Union Colloquium

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Average pulse profiles are generally separable into several components whereas individual components can be described by a Gaussian shape. One generally distinguishes betweencoreandconalcomponents, although it is yet unclear whether core and conal components originate from the same (Lyne & Manchester 1988) or a different emission mechanism (Rankin 1983). Investigating this problem, we studied the behaviour of individual components observed in about 200 profiles of 18 pulsars measured at three different frequencies, i.e. at 1.4 GHz, 4.75 GHz and 10.55 GHz. We unambiguously determined the number, location, width, flux density and spectral index of individual components using a special technique (Kramer et al. 1994). The applied method ensures that only intrinsic features of the pulse profiles are fitted by comparing off-pulse noise statistics and post-fit residuals as a goodness-of-fit estimator. As a first result, we note that all high S/N pulsar profiles can be accurately described by using only a small number (usually ≤ 5) of gaussian components, although we also find an example of a seven component pulse shape (B0740–28). Fitted components determined for different observations of the same pulsar were averaged, producing a grand mean profile which is completely noise-free and thus suitable for a reliable flux density measurement of individual components, for an accurate determination of the pulse width to calculate opening angles, ρ, of the emission cone, or for use as a template for obtaining pulse arrival times.

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Section: Results and Conclusionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Separation of integrated pulse shapes into unique sub-components

Krämer

1996

International Astronomical Union Colloquium

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“…Interestingly, there is a model (Lyne and Manchester 1988) to explain the pulse components that supposes a patchy beam structure (Figure 11). (Lorimer and Kramer 2005, 73) From the stellivore hypothesis framework, an energy source to modify the spin, magnetic field or emission mode of a pulsar would be needed, ensuring its proper function and maintenance.…”

Section: How Could Pulsar Engineering Work?mentioning

confidence: 99%

Pulsar positioning system: a quest for evidence of extraterrestrial engineering

Vidal

2017

International Journal of Astrobiology

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Pulsars have at least two impressive applications. First, they can be used as highly accurate clocks, comparable in stability to atomic clocks; secondly, a small subset of pulsars, millisecond X-ray pulsars, provide all the necessary ingredients for a passive galactic positioning system. This is known in astronautics as X-ray pulsar-based navigation (XNAV). XNAV is comparable to GPS, except that it operates on a galactic scale. I propose a SETI-XNAV research program to test the hypothesis that this pulsar positioning system might be an instance of galactic-scale engineering by extraterrestrial beings (section 4). The paper starts by exposing the basics of pulsar navigation (section 2), continues with a critique of the rejection of the extraterrestrial hypothesis when pulsars were first discovered (section 3). The core section 4 proposes lines of inquiry for SETI-XNAV, related to: the pulsar distribution and power in the galaxy; their population; their evolution; possible pulse synchronizations; pulsar usability when navigating near the speed of light; decoding galactic coordinates; directed panspermia; and information content in pulses. Even if pulsars are natural, they are likely to be used as standards by ETIs in the galaxy (section 5). I discuss possible objections and potential benefits for humanity, whether the research program succeeds or not (section 6).

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“…More detailed studies show that short-period pulsars have wider beams and therefore larger beaming fractions than their long-period counterparts (Narayan & Vivekanand 1983;Lyne & Manchester 1988;Biggs 1990;Tauris & Manchester 1998). It must be said, however, that a consensus on the beaming fraction-period relation has yet to be reached.…”

Section: Emitted Pulsementioning

confidence: 99%