Very-high-energy gamma radiation associated with the unshocked wind of the Crab pulsar

Bogovalov, S. V.; Aharonian, F.

doi:10.1046/j.1365-8711.2000.03250.x

Cited by 81 publications

(99 citation statements)

References 30 publications

(47 reference statements)

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“…Nevertheless, they are (potentially) visible owing to the characteristic inverse Compton radiation of the ultrarelativistic electrons of the wind (Bogovalov & Aharonian 2000). For isolated pulsars, a sharp gamma-ray line can be produced at Comptonization of the electron-positron wind by thermal X-rays arriving from the surface of the neutron star.…”

Section: Astrophysical Vhe Gamma-ray Lines?mentioning

confidence: 99%

“…For isolated pulsars, a sharp gamma-ray line can be produced at Comptonization of the electron-positron wind by thermal X-rays arriving from the surface of the neutron star. The mechanism can be effective only if the conversion of the Poynting flux to kinetic energy of the bulk motion ("acceleration" of the wind) takes place close to the light cylinder (Bogovalov & Aharonian 2000). In the case of pulsars with bright nonthermal broad-band magnetospheric emission, e.g.…”

Section: Astrophysical Vhe Gamma-ray Lines?mentioning

confidence: 99%

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Cold ultrarelativistic pulsar winds as potential sources of galactic gamma-ray lines above 100 GeV

Aharonian

Khangulyan

Malyshev

2012

A&A

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Context. The evidence of line-like spectral features above 100 GeV, in particular at 130 GeV, which have been recently reported from some parts of the Galactic plane, poses serious challenges for any interpretation of this surprise discovery. It is generally believed that the unusually narrow profile of the spectral line cannot be explained by conventional processes in astrophysical objects, and, if real, is likely to be associated with dark matter. Aims. In this paper we argue that cold ultrarelativistic pulsar winds can be alternative sources of very narrow gamma-ray lines. Methods. We demonstrate that Comptonization of a cold ultrarelativistic electron-positron pulsar wind in the deep Klein-Nishina regime can readily provide very narrow (ΔE/E ≤ 0.2) distinct gamma-ray line features. To verify this prediction, we produced photon-count maps based on the Fermi LAT data in the energy interval 100 to 140 GeV. Results. We confirm earlier reports of the presence of marginal gamma-ray line-like signals from three regions of the Galactic plane. Although the maps show some structure inside these regions, unfortunately the limited photon statistics do not allow any firm conclusion in this regard. Conclusions. The confirmation of 130 GeV line emission by low-energy threshold atmospheric Cherenkov telescope systems, in particular by the new 28 m diameter dish of the H.E.S.S. array, would be crucial for resolving the spatial structure of the reported hotspots, and thus for distinguishing between the dark matter and pulsar origins of the "Fermi Lines".

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Section: Astrophysical Vhe Gamma-ray Lines?mentioning

confidence: 99%

Section: Astrophysical Vhe Gamma-ray Lines?mentioning

confidence: 99%

Cold ultrarelativistic pulsar winds as potential sources of galactic gamma-ray lines above 100 GeV

Aharonian

Khangulyan

Malyshev

2012

A&A

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“…In fact, synchrotron self-absorption has not been computed within the considered jet region to account roughly for the radio emission produced outside it. We compute the synchrotron (Pacholczyk 1970) as well as the inverse Compton emission, and the latter is calculated by taking into account KN and angular effects (Bogovalov & Aharonian 2000;Dermer & Böttcher 2006) in the interaction between electrons and photons. The photon-photon opacities due to the ambient photon field are also computed, taking into account angular effects for stellar photons (Gould & Schréder 1967) and adopting the point-like approximation for the stellar radiation (CD photon field is isotropic when dominant).…”

Section: Modeling Radiative Processes In Ls I +61 303mentioning

confidence: 99%

The radio to TeV orbital variability of the microquasar LS I +61 303

Bosch‐Ramon¹,

Paredes²,

Romero³

et al. 2006

A&A

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Context. The microquasar LS I +61 303 has recently been detected at TeV energies by the Cherenkov telescope MAGIC, presenting variability on timescales similar to its orbital period. This system has been intensively observed at different wavelengths during the last three decades, showing a very complex behavior along the orbit. Aims. We aim to explain, using a leptonic model in the accretion scenario, the observed orbital variability and spectrum from radio to TeV energies of LS I +61 303. Methods. We apply a leptonic model based on accretion of matter from the slow inhomogeneous equatorial wind of the primary star, assuming particle injection proportional to the accretion rate. The relativistic electron energy distribution within the binary system is computed taking into account convective/adiabatic and radiative losses. The spectral energy distribution (SED) has been calculated accounting for synchrotron and (Thomson/Klein Nishina -KN-) inverse Compton (IC) processes and the photon-photon absorption in the ambient photon fields. The angle dependence of the photon-photon and IC cross sections has been considered in the calculations. Results. We reproduce the main features of the observed light curves from LS I +61 303 at radio, X-rays, high-energy (HE), and very high-energy (VHE) gamma-rays, and the whole spectral energy distribution. Conclusions. Our model is able to explain the radio to TeV orbital variability taking into account that radiation along the orbit is strongly affected by the variable accretion rate, the magnetic field strength, and by the ambient photon field via dominant IC losses and photon-photon absorption at periastron.

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“…Within these models one can explain the gamma-ray emission of the blazar 1ES 229+200 at z = 0.139 with the spectrum extending up to several TeV [7] and sub-TeV gamma-ray emission from 3C 279 at z = 0.536 [8] (Γ s ∼ 1). Formally, much harder spectra can be expected in the case of Comptonization of an ultrarelativistic outflow [9], in analogy with the cold electron-positron winds in pulsars [10]. Although it is not clear how the ultrarelativistic MHD outflows could form in AGN with a bulk motion Lorentz factor γ ∼ 10 6 , such a scenario, leading to the Klein-Nishina gamma-ray linetype emission [11], cannot be excluded ab initio.…”

Section: Introductionmentioning

confidence: 99%

TeV gamma rays from blazars beyondz=1?

et al. 2013

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At TeV energies, the gamma-ray horizon of the universe is limited to redshifts z ≪ 1, and, therefore, any observation of TeV radiation from a source located beyond z = 1 would call for a revision of the standard paradigm. While robust observational evidence for TeV sources at redshifts z ≥ 1 is lacking at present, the growing number of TeV blazars with redshifts as large as z ≃ 0.5 suggests the possibility that the standard blazar models may have to be reconsidered. We show that TeV gamma rays can be observed even from a source at z ≥ 1, if the observed gamma rays are secondary photons produced in interactions of high-energy protons originating from the blazar jet and propagating over cosmological distances almost rectilinearly. This mechanism was initially proposed as a possible explanation for the TeV gamma rays observed from blazars with redshifts z ∼ 0.2, for which some other explanations were possible. For TeV gamma-ray radiation detected from a blazar with z ≥ 1, this model would provide the only viable interpretation consistent with conventional physics. It would also have far-reaching astronomical and cosmological ramifications. In particular, this interpretation would imply that extragalactic magnetic fields along the line of sight are very weak, in the range 10 −17 G < B < 10 −14 G, assuming random fields with a correlation length of 1 Mpc, and that acceleration of E ≥ 10 17 eV protons in the jets of active galactic nuclei can be very effective.

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Very-high-energy gamma radiation associated with the unshocked wind of the Crab pulsar

Cited by 81 publications

References 30 publications

Cold ultrarelativistic pulsar winds as potential sources of galactic gamma-ray lines above 100 GeV

Cold ultrarelativistic pulsar winds as potential sources of galactic gamma-ray lines above 100 GeV

The radio to TeV orbital variability of the microquasar LS I +61 303

TeV gamma rays from blazars beyondz=1?

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