Discovery of Spatial and Spectral Structure in the X-Ray Emission from the Crab Nebula

Weisskopf, Martin C.; Hester, J. J.; Tennant, Allyn F.; Elsner, Ronald F.; Schulz, Norbert S.; Marshall, Herman L.; Karovska, M.; Nichols, Joy S.; Swartz, Douglas A.; Kolodziejczak, Jeffery J.; O’Dell, Stephen L.

doi:10.1086/312733

Cited by 398 publications

(460 citation statements)

References 19 publications

(46 reference statements)

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“…Taking into account the above properties of the pulsar wind, the observed morphology of PWNe, and first of all the characteristic disk-jet structure (Weisskopf et al 2000;Gaensler and Slane 2006), is naturally explained (Lyubarsky 2002). Namely, the disk is formed by the relatively weakly magnetized equatorial flow, which transfers most of the energy.…”

Section: General Properties Of Pulsar Winds and Structure Of Pwnementioning

confidence: 99%

“…However, it was not until the Hubble Space Telescope (HST; Hester et al 1995) and Chandra (Weisskopf et al 2000) era when the intricate and complex structure of the nebula was revealed (see Figure 1 for the feature nomenclature introduced by Hester et al 1995). These observations have also shown that the bright inner part of the nebula is very dynamic, with apparent velocities corresponding to up to 0.5c (in projection onto the sky) as measured, e.g., from the shifts in wisp positions (Hester et al 2002).…”

Section: Multiwavelength Properties Of the Crabmentioning

confidence: 99%

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Pulsar-Wind Nebulae

et al. 2015

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Section: General Properties Of Pulsar Winds and Structure Of Pwnementioning

confidence: 99%

Section: Multiwavelength Properties Of the Crabmentioning

confidence: 99%

Pulsar-Wind Nebulae

et al. 2015

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“…In the last decade, thanks to the unprecedented imaging power of Chandra, high resolution observations of the inner region of the CN have become available also in the X-ray band, revealing a striking jet-torus structure, knots and rings (Weisskopf et al 2000), previously just barely inferred (Brinkmann et al 1985;Hester 1995). These observations prompted a theoretical effort at modelling PWNe, and the CN in particular, within the framework of time-dependent multi-D MHD.…”

Section: Introductionmentioning

confidence: 99%

Constraints on particle acceleration sites in the Crab nebula from relativistic magnetohydrodynamic simulations

Olmi

Zanna

Amato

et al. 2015

Monthly Notices of the Royal Astronomical Society

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The Crab Nebula is one of the most efficient accelerators in the Galaxy and the only galactic source showing direct evidence of PeV particles. In spite of this, the physical process behind such effective acceleration is still a deep mystery. While particle acceleration, at least at the highest energies, is commonly thought to occur at the pulsar wind termination shock, the properties of the upstream flow are thought to be non-uniform along the shock surface, and important constraints on the mechanism at work come from exact knowledge of where along this surface particles are being accelerated. Here we use axisymmetric relativistic MHD simulations to obtain constraints on the acceleration site(s) of particles of different energies in the Crab Nebula. Various scenarios are considered for the injection of particles responsible for synchrotron radiation in the different frequency bands, radio, optical and X-rays. The resulting emission properties are compared with available data on the multi wavelength time variability of the inner nebula. Our main result is that the X-ray emitting particles are accelerated in the equatorial region of the pulsar wind. Possible implications on the nature of the acceleration mechanism are discussed.

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“…Fine X-ray images taken with the Chandra X-ray Observatory have brought a renaissance to the structural study of the Crab nebula and other pulsar wind nebulae (see Weisskopf et al [59] and references given in a review by Arons [60]). The discovery of two concentric torii is one of the many key observations brought forward by Chandra.…”

Section: Crab Nebulamentioning

confidence: 99%

PoGOLite – A high sensitivity balloon-borne soft gamma-ray polarimeter

Kamae

Andersson

Arimoto

et al. 2008

Astroparticle Physics

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We describe a new balloon-borne instrument (PoGOLite) capable of detecting 10% polarisation from 200 mCrab point-like sources between 25 keV and 80 keV in one 6 hour flight. Polarisation measurements in the soft gamma-ray band are expected to provide a powerful probe into high-energy emission mechanisms as well as the distribution of magnetic fields, radiation fields and interstellar matter. Synchrotron radiation, inverse Compton scattering and propagation through high magnetic fields are likely to produce high degrees of polarisation in the energy band of the instrument. We demonstrate, through tests at accelerators, with radioactive sources and through computer simulations, that PoGOLite will be able to detect degrees of polarisation as predicted by models for several classes of high-energy sources. At present, only exploratory polarisation measurements have been carried out in the soft gamma-ray band. Reduction of the large background produced by cosmic-ray particles while securing a large effective area has been the greatest challenge. PoGOLite uses Compton scattering and photo-absorption in an array of 217 well-type phoswich detector cells made of plastic and BGO scintillators surrounded by a BGO anticoincidence shield and a thick polyethylene neutron shield. The narrow field of view (FWHM = 1.25 msr, 2.0 degrees × 2.0 degrees) obtained with detector cells and the use of thick background shields warrant a large effective area for polarisation measurements (∼228 cm 2 at E = 40 keV) without sacrificing the signal-to-noise ratio. Simulation studies for an atmospheric overburden of 3-4 g/cm 2 indicate that neutrons and gamma-rays entering the PDC assembly through the shields are dominant backgrounds. Off-line event selection based on recorded phototube waveforms and Compton kinematics reduce the background to that expected for a ∼100 mCrab source between 25 keV and 50 keV. A 6 hour observation of the Crab pulsar will differentiate between the Polar Cap/Slot Gap, Outer Gap, and Caustic models with greater than 5σ significance; and also cleanly identify the Compton reflection component in the Cygnus X-1 hard state. Long-duration flights will measure the dependence of the polarisation across the cyclotron absorption line in Hercules X-1. A scaled-down instrument will be flown as a pathfinder mission from the north of Sweden in 2010. The first science flight is planned to take place shortly thereafter.Key words: Instrumentation: detectors, Techniques: polarimetric, Pulsars: general, X-ray: binaries, Stars: neutron, Galaxies: active PACS: 95.30. Gv, 95.55.Ka, 95.55.Qf, 95.75.Hi, 95.85.Pw, 97.60Gv, 97.60.Lf, 97.80.Jp, 98.54.Cm

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Discovery of Spatial and Spectral Structure in the X-Ray Emission from the Crab Nebula

Cited by 398 publications

References 19 publications

Pulsar-Wind Nebulae

Pulsar-Wind Nebulae

Constraints on particle acceleration sites in the Crab nebula from relativistic magnetohydrodynamic simulations

PoGOLite – A high sensitivity balloon-borne soft gamma-ray polarimeter

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