Fitting Pulsar Wind Tori. II. Error Analysis and Applications

Ng, C.‐Y.; Romani, Roger W.

doi:10.1086/523935

Cited by 120 publications

(139 citation statements)

References 21 publications

(22 reference statements)

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“…The presence of two lobes, axisymmetric about a fainter pulsar counterpart, can have contributions from either the torus or jet structures or both of them, with the dominance of one component over the other indistinguishable by the present observation. Using the double torus model of Ng & Romani (2008) to spatially fit the lobes captures the characteristic features of the PWN. Most importantly, it provides a robust estimate of ζ PSR agreeable with constraints derived from geometric modelling of the radio pulse profile and non-detection of γ-ray pulsations from the pulsar.…”

Section: Discussionmentioning

confidence: 99%

“…The 1σ confidence intervals are quoted here. The statistical errors were estimated by performing Monte Carlo Poisson realizations of the best-fit model as recommended in Ng & Romani (2008). To characterize the uncertainty on the estimates associated with the unmodelled components in the fit, especially the eastern tail region, we blanked out the region in the fit and noted the change in parameters.…”

Section: Parametermentioning

confidence: 99%

“…The first panel shows the data in the energy range of 0.5-8 keV. The second one shows the corresponding best-fit geometric model with a double torus (Ng & Romani 2008). The arcs of the torus are marked as black dashed lines to illustrate the geometry.…”

Section: X-ray Spectral Analysismentioning

confidence: 99%

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Constraining the geometry of PSR J0855−4644: A nearby pulsar wind nebula with double torus/jet morphology

Maitra

Venter

Acero

2017

A&A

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Aims. PSR J0855−4644 is a fast-spinning, energetic pulsar discovered at radio wavelengths near the south-eastern rim of the supernova remnant RX J0852.0−4622. A follow-up XMM-Newton observation revealed the pulsar's X-ray counterpart and a slightly asymmetric pulsar wind nebula suggesting possible jet structures. Lying at a distance d ≤ 900 pc, PSR J0855−4644 is a pulsar with one of the highestĖ/d 2 from which no GeV γ-ray pulsations have been detected. With a dedicated Chandra observation we aim to further resolve the possible jet structures of the nebula and study the pulsar's geometry in order to understand the lack of γ-ray pulsations. Methods. We perform detailed spatial modelling to constrain the geometry of the pulsar wind nebula and in particular the pulsar's line of sight (observer angle) ζ PSR defined as the angle between the direction of the observer and the pulsar spin axis. We also perform geometric radio and γ-ray light curve modelling using a hollow-cone radio beam model together with two-pole caustic and outer gap models to further constrain ζ PSR and the magnetic obliquity α defined as the angle between the magnetic and spin axes of the pulsar. Results. The Chandra observation reveals that the compact XMM source, thought to be the X-ray pulsar, can be further resolved into a point source surrounded by an elongated axisymmetric nebula with a longitudinal extent of 10 . The pulsar flux represents only ∼ 1% of the XMM compact source and its spectrum is well described by a blackbody of temperature kT = 0.2 keV while the surrounding nebula has a much harder spectrum (Γ = 1.1 for a power-law model). Assuming the origin of the extended emission is from a double torus yields ζ PSR = 32.5 • ± 4.3 • . The detection of thermal X-rays from the pulsar may point to a low value of |ζ − α| if this emission originates from a heated polar cap. Independent constraints from geometric light curve modelling yield α 55 • and ζ 55 • , and 10 • |ζ − α| 30 • . A χ 2 fit to the radio light curve yields a best fit at (α, ζ PSR ) = (22 • , 8 • ), with an alternative fit at (α, ζ PSR ) = (9 • , 25 • ) within 3σ. The lack of non-thermal X-ray emission from the pulsar further supports low values for α and ζ under the assumption that X-rays and γ-rays are generated in the same region of the pulsar magnetosphere. Such a geometry would explain, in the standard caustic pulsar model picture, the radio-loud and γ-ray-quiet behaviour of this highĖ/d 2 pulsar.

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Section: Discussionmentioning

confidence: 99%

Section: Parametermentioning

confidence: 99%

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Constraining the geometry of PSR J0855−4644: A nearby pulsar wind nebula with double torus/jet morphology

Maitra

Venter

Acero

2017

A&A

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“…1 for examples and the aforementioned reviews for more). Detailed modeling of the geometries (14) and emission mechanisms (15) constrain both the properties of the pulsar wind and shock acceleration mechanisms. Important open questions here are the nature and composition of the pulsar wind, specifically whether it consists of only e þ ∕e − pairs or also ions (e.g., ref.…”

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confidence: 99%

Grand unification of neutron stars

Kaspi

2010

Proc. Natl. Acad. Sci. U.S.A.

217

180

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The last decade has shown us that the observational properties of neutron stars are remarkably diverse. From magnetars to rotating radio transients, from radio pulsars to isolated neutron stars, from central compact objects to millisecond pulsars, observational manifestations of neutron stars are surprisingly varied, with most properties totally unpredicted. The challenge is to establish an overarching physical theory of neutron stars and their birth properties that can explain this great diversity. Here I survey the disparate neutron stars classes, describe their properties, and highlight results made possible by the Chandra X-Ray Observatory, in celebration of its 10th anniversary. Finally, I describe the current status of efforts at physical “grand unification” of this wealth of observational phenomena, and comment on possibilities for Chandra’s next decade in this field.

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“…[42], and Refs. [43,44] PHYSICAL REVIEW LETTERS 120, 031104 (2018) In most cases, log 10 O S I < 0 and the noise model is clearly favored; the single exception is J1932 þ 17, for which log 10 O S I ∼ 0, so that we can make no conclusive statement about which hypothesis is preferred. (The presence of this nonsignificant outlier is to be expected, as it was already identified in Ref.…”

mentioning

confidence: 99%

First Search for Nontensorial Gravitational Waves from Known Pulsars

Abbott¹,

Abbott²,

Abbott³

et al. 2018

Phys. Rev. Lett.

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We present results from the first directed search for nontensorial gravitational waves. While general relativity allows for tensorial (plus and cross) modes only, a generic metric theory may, in principle, predict waves with up to six different polarizations. This analysis is sensitive to continuous signals of scalar, vector, or tensor polarizations, and does not rely on any specific theory of gravity. After searching data from the first observation run of the advanced LIGO detectors for signals at twice the rotational frequency of 200 known pulsars, we find no evidence of gravitational waves of any polarization. We report the first upper limits for scalar and vector strains, finding values comparable in magnitude to previously published limits for tensor strain. Our results may be translated into constraints on specific alternative theories of gravity.

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Fitting Pulsar Wind Tori. II. Error Analysis and Applications

Cited by 120 publications

References 21 publications

Constraining the geometry of PSR J0855−4644: A nearby pulsar wind nebula with double torus/jet morphology

Constraining the geometry of PSR J0855−4644: A nearby pulsar wind nebula with double torus/jet morphology

Grand unification of neutron stars

First Search for Nontensorial Gravitational Waves from Known Pulsars

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