scholarly journals PeV Emission of the Crab Nebula: Constraints on the Proton Content in Pulsar Wind and Implications

2021 ◽  
Vol 922 (2) ◽  
pp. 221
Author(s):  
Ruo-Yu Liu ◽  
Xiang-Yu Wang
Keyword(s):  
Energy Content ◽  
Crab Nebula ◽  
Cosmic Ray ◽  
Ultrahigh Energy ◽  
Pulsar Wind Nebulae ◽  
Air Shower ◽  
Pulsar Wind ◽  
The Crab Nebula ◽  
Pulsar Winds ◽  
Cosmic Ray Flux

Abstract Recently, two photons from the Crab Nebula with energy of approximately 1 PeV were detected by the Large High Altitude Air Shower Observatory (LHAASO), opening an ultrahigh-energy window for studying pulsar wind nebulae (PWNe). Remarkably, the LHAASO spectrum at the highest-energy end shows a possible hardening, which could indicate the presence of a new component. A two-component scenario with a main electron component and a secondary proton component has been proposed to explain the whole spectrum of the Crab Nebula, requiring a proton energy of 1046–1047 erg remaining in the present Crab Nebula. In this paper, we study the energy content of relativistic protons in pulsar winds using the LHAASO data of the Crab Nebula, considering the effect of diffusive escape of relativistic protons. Depending on the extent of the escape of relativistic protons, the total energy of protons lost in the pulsar wind could be 10–100 times larger than that remaining in the nebula presently. We find that the current LHAASO data allow up to (10–50)% of the spindown energy of pulsars being converted into relativistic protons. The escaping protons from PWNe could make a considerable contribution to the cosmic-ray flux of 10–100 PeV. We also discuss the leptonic scenario for the possible spectral hardening at PeV energies.

Hard X-ray emission from pulsar-wind nebulae

2016 ◽  
Vol 82 (5) ◽  
Author(s):  
Stephen P. Reynolds
Keyword(s):  
Energy Distribution ◽  
Gamma Rays ◽  
Crab Nebula ◽  
Cosmic Ray ◽  
Spectral Structure ◽  
Particle Spectrum ◽  
Pulsar Wind Nebulae ◽  
Pulsar Wind ◽  
Tev Gamma Rays ◽  
The Crab Nebula

Pulsar-wind nebulae emit an extremely broad spectrum of continuum radiation, from low radio frequencies to TeV gamma rays. The part of the spectral energy distribution (SED) from radio through MeV gamma rays is due to synchrotron emission from a distribution of relativistic electrons (or pairs) which can be described by one or more power laws. This spectrum exhibits that particle energy distribution, responsible also for the higher-energy (GeV–TeV) part of the SED, due to inverse-Compton upscattering of one of three photon fields: the synchrotron spectrum, the cosmic microwave background, or ambient optical/infrared photons. However, in a few sources, primary hadrons may produce GeV–TeV gamma rays through the decay of neutral pions produced in inelastic cosmic-ray collisions with thermal gas. The higher-energy end of the particle spectrum, producing synchrotron photons above approximately 10 keV, holds clues to the particle acceleration process. However, its detailed study requires imaging spectroscopy in this energy range, not available until the NuSTAR mission beginning in 2012, which performs true imaging between 3 and 78 keV with ${\sim}1^{\prime }$ angular resolution. I review NuSTAR observations of the first three pulsar-wind nebulae (PWNe) to be examined in this way: the Crab Nebula, G21.5–0.9 and MSH 15–52. All three show spectral structure not previously known: spectral steepening in certain locations and overall source shrinkage with increasing photon energy. The Crab Nebula has different shrinkage rates along the torus and along the northwest counter-jet. The latter rate is similar to that for both the other sources (FWHM $\propto E^{m}$ with $m\sim -0.2$). I discuss implications of these results for models of particle transport in PWNe.

scholarly journals A corrugated termination shock in pulsar wind nebulae?

2016 ◽  
Vol 82 (4) ◽  
Author(s):  
Martin Lemoine
Keyword(s):  
Magnetic Field ◽  
Crab Nebula ◽  
Radiation Reaction ◽  
Termination Shock ◽  
Pulsar Wind Nebulae ◽  
Order Unity ◽  
Poynting Flux ◽  
Electron Positron ◽  
Pulsar Wind ◽  
The Crab Nebula

Successful phenomenological models of pulsar wind nebulae assume efficient dissipation of the Poynting flux of the magnetized electron–positron wind as well as efficient acceleration of the pairs in the vicinity of the termination shock, but how this is realized is not yet well understood. This paper suggests that the corrugation of the termination shock, at the onset of nonlinearity, may lead towards the desired phenomenology. Nonlinear corrugation of the termination shock would convert a fraction of order unity of the incoming ordered magnetic field into downstream turbulence, slowing down the flow to sub-relativistic velocities. The dissipation of turbulence would further preheat the pair population on short length scales, close to equipartition with the magnetic field, thereby reducing the initial high magnetization to values of order unity. Furthermore, it is speculated that the turbulence generated by the corrugation pattern may sustain a relativistic Fermi process, accelerating particles close to the radiation reaction limit, as observed in the Crab nebula. The required corrugation could be induced by the fast magnetosonic modes of downstream nebular turbulence; but it could also be produced by upstream turbulence, either carried by the wind or seeded in the precursor by the accelerated particles themselves.

scholarly journals Peculiar Differences in Radio and X-ray Synchrotron Radiation from Pulsar Wind Nebulae

2004 ◽  
Vol 218 ◽  
pp. 221-224
Author(s):  
John R. Dickel ◽  
Shiya Wang
Keyword(s):  
Synchrotron Radiation ◽  
Radio Emission ◽  
Supernova Remnants ◽  
Crab Nebula ◽  
Pulsar Wind Nebulae ◽  
X Ray ◽  
Pulsar Wind ◽  
The Crab Nebula

Several Crab-type supernova remnants appear to have very bright non-thermal X-ray cores just around the pulsar or expected pulsar. This X-ray brightness is often not matched by a corresponding increase in radio emission. The best example of this phenomenon is in N157B in the LMC. G21.5−0.9 and possibly 3C 58 also show it while the Crab Nebula and 0540−69.3 do not. Some method to enhance the higher energy particles must be present in these objects.

scholarly journals MULTI-TeV GAMMA-RAY OBSERVATION FROM THE CRAB NEBULA USING THE TIBET-III AIR SHOWER ARRAY FINELY TUNED BY THE COSMIC RAY MOON'S SHADOW

2009 ◽  
Vol 692 (1) ◽  
pp. 61-72 ◽  
Author(s):  
M. Amenomori ◽  
X. J. Bi ◽  
D. Chen ◽  
S. W. Cui ◽  
Danzengluobu ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Crab Nebula ◽  
Cosmic Ray ◽  
Air Shower ◽  
The Crab Nebula ◽  
Shower Array ◽  
Air Shower Array

scholarly journals Diffusion and advection model for particle transport in young pulsar wind nebulae

2012 ◽  
Vol 8 (S291) ◽  
pp. 265-268
Author(s):  
Xiaping Tang ◽  
Roger A. Chevalier
Keyword(s):  
Spectral Index ◽  
Particle Transport ◽  
Crab Nebula ◽  
Outer Boundary ◽  
Outer Part ◽  
Pulsar Wind Nebulae ◽  
Pure Diffusion ◽  
Pulsar Wind ◽  
Kink Instability ◽  
The Crab Nebula

AbstractThe magnetohydrodynamic (MHD) model for young pulsar wind nebulae (PWN) has been successful in reproducing many features of the nebulae. The model is characterized by a termination shock (TS) between the PWN and unshocked pulsar wind. Relativistic particles are injected at the TS and follow an advective flow to the outer boundary. However, toroidal structure of well studied young PWN like the Crab Nebula, 3C 58 and G21.5-0.9 is only present in the region close to the TS. In the outer parts of the nebulae, filamentary and loop-like structure is observed. Also, the radial variation of spectral index due to synchrotron losses is smoother than expected in the MHD flow model. We find that a pure diffusion model with energy independent diffusion and a transmitting boundary can reproduce the basic data on nebular size and spectral index variation for the Crab, 3C 58, and G21.5-0.9. Energy dependent diffusion is also discussed. Power law variations of the coefficient with energy are degenerate with variation in the input particle energy distribution index in the steady state case. Monte Carlo simulations of particle transport with both diffusion and advection for the Crab nebula and 3C 58 suggest a picture in which advection dominates the inner part of the PWN where toroidal structure is clearly present. Diffusion dominates the outer part of the PWN where filamentary and loop-like structure is observed. The source of the chaotic field is uncertain, but may be related to Rayleigh-Taylor instability at the outer boundary of young nebulae and/or the kink instability of the toroidal magnetic field.

scholarly journals Reverberation of pulsar wind nebulae (I): impact of the medium properties and other parameters upon the extent of the compression

2020 ◽  
Vol 499 (2) ◽  
pp. 2051-2062 ◽  
Author(s):  
R Bandiera ◽  
N Bucciantini ◽  
J Martín ◽  
B Olmi ◽  
D F Torres
Keyword(s):  
Ambient Medium ◽  
Crab Nebula ◽  
Late Phase ◽  
Pulsar Wind Nebulae ◽  
Reverse Shock ◽  
Pressure Profiles ◽  
Pulsar Wind ◽  
Radiation Processes ◽  
The Crab Nebula

ABSTRACT The standard approach to the long-term evolution of pulsar wind nebulae (PWNe) is based on one-zone models treating the nebula as a uniform system. In particular for the late phase of evolved systems, many of the generally used prescriptions are based on educated guesses for which a proper assessment lacks. Using an advanced radiative code, we evaluate the systematic impact of various parameters, like the properties of the supernova ejecta, of the inner pulsar, as well of the ambient medium, upon the extent of the reverberation phase of PWNe. We investigate how different prescriptions shift the starting time of the reverberation phase, how this affects the amount of the compression, and how much of this can be ascribable to the radiation processes. Some critical aspects are the description of the reverse shock evolution, the efficiency by which at later times material from the ejecta accretes on to the swept-up shell around the PWN, and finally the density, velocity, and pressure profiles in the surrounding supernova remnant. We have explicitly treated the cases of the Crab Nebula, and of J1834.9−0846, taken to be representatives of the more and the less energetic pulsars, respectively. Especially for the latter object, the prediction of large compression factors is confirmed, even larger in the presence of radiative losses, also confirming our former prediction of periods of superefficiency during the reverberation phase of some PWNe.

scholarly journals Multi-D magnetohydrodynamic modelling of pulsar wind nebulae: recent progress and open questions

2016 ◽  
Vol 82 (6) ◽  
Author(s):  
B. Olmi ◽  
L. Del Zanna ◽  
E. Amato ◽  
N. Bucciantini ◽  
A. Mignone
Keyword(s):  
Gamma Ray ◽  
Crab Nebula ◽  
Three Dimensional ◽  
Pulsar Wind Nebulae ◽  
Dissipation Process ◽  
Tearing Instability ◽  
Open Questions ◽  
Pulsar Wind ◽  
The Crab Nebula

In the last decade, the relativistic magnetohydrodynamic (MHD) modelling of pulsar wind nebulae, and of the Crab nebula in particular, has been highly successful, with many of the observed dynamical and emission properties reproduced down to the finest detail. Here, we critically discuss the results of some of the most recent studies: namely the investigation of the origin of the radio emitting particles and the quest for the acceleration sites of particles of different energies along the termination shock, by using wisp motions as a diagnostic tool; the study of the magnetic dissipation process in high magnetization nebulae by means of new long-term three-dimensional simulations of the pulsar wind nebula evolution; the investigation of the relativistic tearing instability in thinning current sheets, leading to fast reconnection events that might be at the origin of the Crab nebula gamma-ray flares.

scholarly journals Twinkling pulsar wind nebulae in the synchrotron cut-off regime and the γ-ray flares in the Crab Nebula

2012 ◽  
Vol 421 (1) ◽  
pp. L67-L71 ◽  
Author(s):  
A. M. Bykov ◽  
G. G. Pavlov ◽  
A. V. Artemyev ◽  
Yu. A. Uvarov
Keyword(s):  
Crab Nebula ◽  
Pulsar Wind Nebulae ◽  
Γ Ray ◽  
Pulsar Wind ◽  
The Crab Nebula

scholarly journals Dust masses and grain size distributions of a sample of Galactic pulsar wind nebulae

2019 ◽  
Vol 491 (4) ◽  
pp. 6020-6031 ◽  
Author(s):  
F D Priestley ◽  
M J Barlow ◽  
I De Looze ◽  
H Chawner
Keyword(s):  
Grain Size ◽  
Crab Nebula ◽  
Dust Emission ◽  
Size Distributions ◽  
Pulsar Wind Nebulae ◽  
Synchrotron Source ◽  
Total Dust ◽  
Dust Mass ◽  
Pulsar Wind ◽  
The Crab Nebula

ABSTRACT We calculate dust spectral energy distributions (SEDs) for a range of grain sizes and compositions, using physical properties appropriate for five pulsar wind nebulae (PWNe) from which dust emission associated with the ejecta has been detected. By fitting the observed dust SED with our models, with the number of grains of different sizes as the free parameters, we are able to determine the grain size distribution and total dust mass in each PWN. We find that all five PWNe require large ($\ge 0.1 \, {\rm \mu m}$) grains to make up the majority of the dust mass, with strong evidence for the presence of micron-sized or larger grains. Only two PWNe contain non-negligible quantities of small ($\lt 0.01 \, {\rm \mu m}$) grains. The size distributions are generally well-represented by broken power laws, although our uncertainties are too large to rule out alternative shapes. We find a total dust mass of $0.02\rm {-}0.28 \, {\rm M}_\odot$ for the Crab Nebula, depending on the composition and distance from the synchrotron source, in agreement with recent estimates. For three objects in our sample, the PWN synchrotron luminosity is insufficient to power the observed dust emission, and additional collisional heating is required, either from warm, dense gas as found in the Crab Nebula, or higher temperature shocked material. For G54.1+0.3, the dust is heated by nearby OB stars rather than the PWN. Inferred dust masses vary significantly depending on the details of the assumed heating mechanism, but in all cases large mass fractions of micron-sized grains are required.

scholarly journals Model of radio emission from spherically symmetric pulsar wind nebulae

2012 ◽  
Vol 8 (S291) ◽  
pp. 511-513
Author(s):  
Shuta J. Tanaka
Keyword(s):  
Radio Emission ◽  
Spatial Structure ◽  
Power Law ◽  
Crab Nebula ◽  
Particle Energy ◽  
Zone Model ◽  
Pulsar Wind Nebulae ◽  
Adiabatic Cooling ◽  
Pulsar Wind ◽  
The Crab Nebula

AbstractWe study radio emission from pulsar wind nebulae (PWNe) considering the observed spatial structure. We assume spherical symmetry of the PWN, and model the evolution of the magnetic field and the particle energy distribution. We do not consider the synchrotron cooling of particles but consider the adiabatic cooling, because we are mostly interested in the radio emission from PWNe. The model is applied to the Crab Nebula and succeeds to reproduce the observed spatially integrated spectrum in radio with a single power-law injection. In our previous work (a one-zone model), in contrast, the integrated spectrum of the Crab Nebula is reproduced by a broken power-law injection of particles. However, the spatial structure in radio is inconsistent with observations and we need a radial velocity profile which is very different from the model by Kennel & Coroniti. Further studies of the spatial structure of PWNe are important to understand the origin of the radio emission from young PWNe.

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