Energetic radiation from rapidly spinning pulsars. I - Outer magnetosphere gaps. II - VELA and Crab

Cheng, K. S.; Ho, Cheng; Ruderman, M.

doi:10.1086/163829

Cited by 838 publications

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“…Pair creation is also expected to occur in outer gaps, if they exist in certain magnetospheric configurations. In this case, the pairs are created by the photon-photon process in which γ-ray photons of energy γ from primary particles accelerated in the gap and X-ray photons X from secondary particles or from the hot polar caps produce an electron and positron [126,152]. The threshold for this process is γ X = 2/(1 − cos θ), where the energies are in units of mc 2 and θ is the angle between the photon momenta.…”

Section: Pair Cascadesmentioning

confidence: 99%

“…Models for high-energy emission from the outer magnetosphere had in fact already been developed. The outer gap model [126,65] locates the acceleration region above the null charge surface (the surface where the corotation charge for a static dipole changes sign) near the last open field lines. The slot gap [127,128] is an extension of the polar cap where acceleration occurs in a narrow charge-depleted zone along the last open field lines from 13 the neutron star surface to near the light cylinder.…”

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confidence: 99%

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Gamma-ray pulsars: A gold mine

Grenier

Harding

2015

Comptes Rendus. Physique

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The most energetic neutron stars, powered by their rotation, are capable of producing pulsed radiation from the radio up to γ rays with nearly TeV energies. These pulsars are part of the universe of energetic and powerful particle accelerators, using their uniquely fast rotation and formidable magnetic fields to accelerate particles to ultra-relativistic speed. The extreme properties of these stars provide an excellent testing ground, beyond Earth experience, for nuclear, gravitational, and quantum-electrodynamical physics. A wealth of γ-ray pulsars has recently been discovered with the Fermi Gamma-Ray Space Telescope. The energetic γ rays enable us to probe the magnetospheres of neutron stars and particle acceleration in this exotic environment. We review the latest developments in this field, beginning with a brief overview of the properties and mysteries of rotation-powered pulsars, and then discussing γ-ray observations and magnetospheric models in more detail. RésuméLes pulsars γ : une mine d'or : Lesétoilesà neutrons les plus puissantes, qui tirent leurénergie de leur rotation, sont capables d'émettre des impulsions lumineuses des ondes radio jusqu'aux rayons γ d'énergies proches du TeV. Ces pulsars font partie des puissants accélérateurs de particules de l'Univers, profitant de leur rotation unique et de leur formidable champ magnétique pour accélérer des particules jusqu'à des vitesses ultra-relativistes. Les propriétés extrêmes de cesétoiles permettent de tester la physique nucléaire, la gravitation et l'électrodynamique quantique dans des conditions inaccessibles sur Terre. Le télescope gamma spatial Fermi vient de révéler un richeéchantillon de pulsars γ. Leur rayonnement γénergétique permet de sonder la magnétosphère desétoilesà neutrons et d'étudier l'accélération de particules dans cet environnement exotique. Nous présentons les derniers développements de ce domaine, en commençant par une rapide revue des propriétés et mystères soulevés par ces pulsars, puis en détaillant plus avant les observations γ et les modèles magnétosphériques.Keywords : pulsar ; neutron star ; magnetosphere ; gamma rays ; acceleration Mots-clés : pulsar ;étoileà neutrons ; magnétosphère ; rayons gamma ; accélération Neutron stars, pulsars, and their puzzlesA neutron star is an extreme object in many regards. It is a compact, rapidly spinning, highly magnetized star, formed from the core of a massive star which runs out of nuclear power and collapses under its own gravity, with 53 radio-loud and γ-loud young pulsars (orange upward triangles), 37 radio-faint and γ-loud young pulsars (red downward triangles), 71 radio-loud and γ-loud millisecond pulsars (green filled circles, circled in black and red when in black-widow and redback systems, respectively), and 2256 other radio pulsars (light blue). Recently discovered millisecond pulsars, with noṖ measurement yet, are plotted as squares atṖ near 10 −21 . Lines of constant spin-down power (brown) and polar magnetic field strength (green) are given for a magnetic dipole i...

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Section: Pair Cascadesmentioning

confidence: 99%

mentioning

confidence: 99%

Gamma-ray pulsars: A gold mine

Grenier

Harding

2015

Comptes Rendus. Physique

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“…Zhang et al, 2000), outer gap (OG, e.g. Cheng et al, 1986) and space charge limited flow (SCLF, e.g. Arons & Scharlemenn, 1979).…”

Section: The Model With Constant Gap Potential Dropmentioning

confidence: 99%

What can the braking indices tell us about the nature of pulsars?

Yue

Zhu

2007

Advances in Space Research

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As a result of observational difficulties, braking indices of only six rotation-powered pulsars are obtained with certainty, all of which are remarkably smaller than the value (n = 3) expected for pure magnetodipole radiation model. This is still a real fundamental question not being well answered after nearly forty years of the discovery of pulsar. The main problem is that we are shamefully not sure about the dominant mechanisms that result in pulsars' spin-down. Based on the previous works, the braking index is re-examined, with a conclusion of suggesting a constant gap potential drop for pulsars with magnetospheric activities. New constrains on model parameters from observed braking indices are presented.

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“…Among the earliest scientific results from the LAT was the discovery of a large population of radio-quiet gamma-ray pulsars (Abdo et al 2009b;Saz Parkinson et al 2010), using a new blind-search technique developed specifically for the very long time series expected with the LAT (Atwood et al 2006). These findings confirmed some predictions that many of the unidentified EGRET sources in the Galactic plane were pulsars(e.g., Yadigaroglu & Romani 1995), favoring outer gap pulsar models (Cheng et al 1986;Romani 1996Romani , 2014, where the gamma rays are generated in the outer magnetosphere, as opposed to polar cap models, where the emission comes from closer to the neutron star surface(e.g., Harding & Muslimov 1998).…”

Section: Introductionmentioning

confidence: 99%

Classification and Ranking of Fermi Lat Gamma-Ray Sources From the 3fgl Catalog Using Machine Learning Techniques

Parkinson

et al. 2016

ApJ

135

174

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We apply a number of statistical and machine learning techniques to classify and rank gamma-ray sources from the Third Fermi Large Area Telescope Source Catalog (3FGL), according to their likelihood of falling into the two major classes of gamma-ray emitters: pulsars (PSR) or active galactic nuclei (AGNs). Using 1904 3FGL sources that have been identified/associated with AGNs (1738) and PSR (166), we train (using 70% of our sample) and test (using 30%) our algorithms and find that the best overall accuracy (>96%) is obtained with the Random Forest (RF) technique, while using a logistic regression (LR) algorithm results in only marginally lower accuracy. We apply the same techniques on a subsample of 142 known gamma-ray pulsars to classify them into two major subcategories: young (YNG) and millisecond pulsars (MSP). Once more, the RF algorithm has the best overall accuracy (∼90%), while a boosted LR analysis comes a close second. We apply our two best models (RF and LR) to the entire 3FGL catalog, providing predictions on the likely nature of unassociated sources, including the likely type of pulsar (YNG or MSP). We also use our predictions to shed light on the possible nature of some gamma-ray sources with known associations (e.g., binaries, supernova remnants/pulsar wind nebulae). Finally, we provide a list of plausible X-ray counterparts for some pulsar candidates, obtained using Swift, Chandra, and XMM. The results of our study will be of interest both for in-depth follow-up searches (e.g., pulsar) at various wavelengths and for broader population studies.

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Energetic radiation from rapidly spinning pulsars. I - Outer magnetosphere gaps. II - VELA and Crab

Cited by 838 publications

References 0 publications

Gamma-ray pulsars: A gold mine

Gamma-ray pulsars: A gold mine

What can the braking indices tell us about the nature of pulsars?

Classification and Ranking of Fermi Lat Gamma-Ray Sources From the 3fgl Catalog Using Machine Learning Techniques

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