Detection of change in rotation measure of the Vela pulsar

Hamilton, P. A.; McCulloch, P. M.; Manchester, R. N.; Ables, J. G.; Komesaroff, M. M.

doi:10.1038/265224a0

Cited by 23 publications

(23 citation statements)

References 7 publications

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“…The original value of Radhakrishnan & Cooke (1969) is ( 0 \ with an uncertainty of B5¡. Hamilton et al (1977) made 47¡ measurements over several years, all of which are consistent with A detailed decomposition into four ( 0 \ 64¡^1¡ .5. separate pulse components was performed by Krishnamohan & Downs (1983), in which they concluded that one of the components was polarized in the mode orthogonal to the other three. However, they did not attempt an absolute measurement of the angle Bietenholz et al (1991) mea-( 0 .…”

Section: Fig 8è(a)mentioning

confidence: 65%

Vela Pulsar and Its Synchrotron Nebula

Helfand

Gotthelf

Halpern

2001

ApJ

283

305

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We present high-resolution Chandra X-ray observations of PSR B0833[45, the 89 ms pulsar associated with the Vela supernova remnant. We have acquired two observations separated by 1 month to search for changes in the pulsar and its environment following an extreme glitch in its rotation frequency. We Ðnd a well-resolved nebula with a toroidal morphology remarkably similar to that observed in the Crab Nebula, along with an axial Crab-like jet. Between the two observations, taken D3 ] 105 s and D3 ] 106 s after the glitch, the Ñux from the pulsar is found to be steady to within 0.75% ; the 3 p limit on the fractional increase in the pulsarÏs X-ray Ñux is of the inferred glitch energy. We use [10~5 this limit to constrain parameters of glitch models and neutron star structure. We do Ðnd a signiÐcant increase in the Ñux of the nebulaÏs outer arc ; if associated with the glitch, the inferred propagation velocity is similar to that seen in the brightening of the Crab Nebula wisps. We propose an explana-Z0.7c, tion for the X-ray structure of the Vela synchrotron nebula based on a model originally developed for the Crab Nebula. In this model, the bright X-ray arcs are the shocked termination of a relativistic equatorial pulsar wind that is contained within the surrounding kidney-bean shaped synchrotron nebula comprising the postshock, but still relativistic, Ñow. In a departure from the Crab model, the magnetization parameter p of the Vela pulsar wind is allowed to be of order unity ; this is consistent with the simplest MHD transport of magnetic Ðeld from the pulsar to the nebula, where B ¹ 4 ] 10~4 G. The inclination angle of the axis of the equatorial torus with respect to the line of sight is identical to that of the rotation axis of the pulsar as previously measured from the polarization of the radio pulse. The projection of the rotation axis on the sky may also be close to the direction of proper motion of the pulsar if previous radio measurements were confused by orthogonal-mode polarized components. We review e †ects that may enhance the probability of alignment between the spin axis and space velocity of a pulsar, and speculate that short-period, slowly moving pulsars are just the ones best-suited to producing synchrotron nebulae with such aligned structures. Previous interpretations of the compact Vela nebula as a bow-shock in a very weakly magnetized wind su †ered from data of inadequate spatial resolution and less plausible physical assumptions.

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Section: Fig 8è(a)mentioning

confidence: 65%

Vela Pulsar and Its Synchrotron Nebula

Helfand

Gotthelf

Halpern

2001

ApJ

283

305

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“…There are a number of cases in which the RM differs significantly from previous values, in particular that of the Vela pulsar. In 1977, the RM of the Vela pulsar was found to be 38 rad m −2 (Hamilton et al 1977b). In a later paper, Hamilton, Hall & Costa (1985) showed that the RM had increased to 46 rad m −2 and in fact appeared to be linearly increasing since at least 1970.…”

Section: Resultsmentioning

confidence: 99%

Evidence for alignment of the rotation and velocity vectors in pulsars

Johnston

Hobbs

Vigeland

et al. 2005

Monthly Notices of the Royal Astronomical Society

225

245

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We present strong observational evidence for a relationship between the direction of a pulsar's motion and its rotation axis. We show carefully calibrated polarization data for 25 pulsars, 20 of which display linearly polarized emission from the pulse longitude at closest approach to the magnetic pole. Such data allow determination of the position angle of the linear polarisation which in turn reflects the position angle of the rotation axis. Of these 20 pulsars, 10 show an offset between the velocity vector and the polarisation position angle which is either less than 10\degr or more than 80\degr, a fraction which is very unlikely by random chance. We believe that the bimodal nature of the distribution arises from the presence of orthogonal polarisation modes in the pulsar radio emission. In some cases this orthogonal ambiguity is resolved by observations at other wavelengths so that we conclude that the velocity vector and the rotation axis are aligned at birth. Strengthening the case is the fact that 4 of the 5 pulsars with ages less than 3 Myr show this relationship, including the Vela pulsar. We discuss the implications of these findings in the context of the Spruit & Phinney (1998)\nocite{sp98} model of pulsar birth-kicks. We point out that, contrary to claims in the literature, observations of double neutron star systems do not rule out aligned kick models and describe a possible observational test involving the double pulsar system.Comment: MNRAS, In Pres

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“…Hamilton et al (1977Hamilton et al ( , 1985 analyze the variations of RM and DM for the Vela pulsar, finding an approximately linear variation in both with slopes of 0.73 rad m −2 yr −1 and −0.04 cm −3 pc yr −1 for RM and DM respectively. They interpret the RM and DM variations as the result of the relative motion of a magnetized filament of the Vela supernova remnant across the line-of-sight and estimated the electron density and the effective mean line-of-sight component of magnetic field in the filament.…”

Section: Introductionmentioning

confidence: 99%

Rotation measure variations for 20 millisecond pulsars

Yan¹,

Manchester²,

Hobbs³

et al. 2011

Astrophys Space Sci

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project. It is found that the observed variations are dominated by changes in the Faraday rotation occurring in the Earth's ionosphere. Two ionospheric models are used to correct for the ionospheric contribution and it is found that one based on the International Reference Ionosphere gave the best results. Little or no significant long-term variation in interstellar RM was found with limits typically about 0.1 rad m −2 yr −1 in absolute value. In a few cases, apparently significant RM variations over timescales of a few 100 days or more were seen. These are unlikely to be due to localised magnetised regions crossing the line of sight since the implied magnetic fields are too high. Most probably they are statistical fluctuations due to random spatial and temporal variations in the interstellar electron density and magnetic field along the line of sight.

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Detection of change in rotation measure of the Vela pulsar

Cited by 23 publications

References 7 publications

Vela Pulsar and Its Synchrotron Nebula

Vela Pulsar and Its Synchrotron Nebula

Evidence for alignment of the rotation and velocity vectors in pulsars

Rotation measure variations for 20 millisecond pulsars

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