Pulsar wind zone processes in LS 5039

Sierpowska-Bartosik, A.; Torres, D. F.

doi:10.1016/j.astropartphys.2008.09.009

Cited by 58 publications

(56 citation statements)

References 73 publications

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“…However, as noted in Bosch-Ramon & Khangulyan (2009), they are not likely to be important for relativistic protons/nuclei in the environment of LS 5039 with relatively low matter (for pp), X-ray photon (for photomeson production and photodisintegration) densities, and very long proton synchrotron timescales. Pulsar wind comptonization or pulsar magnetospheric radiation have been discussed as potential sources of GeV-TeV emission in LS 5039 (e.g., Sierpowska-Bartosik et al 2008;Cerutti et al 2008;Takata et al 2014). Considering these components would imply a multi-population, non-homogeneous, non-point-like model (see iii) and the presence of a powerful non-accreting pulsar in the system.…”

Section: Discussionmentioning

confidence: 99%

Gamma-ray binaries beyond one-zone models: an application to LS 5039

Palacio

Bosch‐Ramon

Romero

2015

A&A

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Context. Several binary systems hosting massive stars present gamma-ray emission. In most of these systems, despite detailed observational information being available, the nature and the structure of the emitter are still poorly known. Aims. We investigate the validity of the so-called one-zone approximation for the high-energy emitter in binary systems hosting a massive star. In particular, the case of LS 5039 is considered. Methods. Assuming a point-like emitter at rest, the presence of a nearby massive star, and the observed MeV and GeV fluxes as a reference, a non-thermal leptonic model is systematically applied for different locations, magnetic fields, and non-radiative losses. This allows us to identify both the emitter configurations that are most compatible with observations and inconsistencies between model predictions and the available data. Results. In the case of LS 5039, the best parameter combination is fast non-radiative cooling and a low magnetic field. However, discrepancies appear when comparing the model results at the MeV and GeV energy ranges with the observed fluxes. Predictions fail when the orbital motion is included in the analysis, because emitters and energy budgets that are too large are required. Values of X-ray and TeV fluxes that are too high are predicted in such a case, along half of the orbit. Conclusions. We show that the radiation in LS 5039 does not come from only one electron population, and the emitter is likely extended and inhomogeneous with a low magnetic field. We suggest that the emitter moves at relativistic velocities with Doppler boosting playing a significant role.

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Section: Discussionmentioning

confidence: 99%

Gamma-ray binaries beyond one-zone models: an application to LS 5039

Palacio

Bosch‐Ramon

Romero

2015

A&A

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“…Then, all else being equal, the peak flux phase is determined by where the seed photon density is highest and by geometry; favorable when the highenergy electrons are seen behind the star by the observer, e.g., Dubus et al (2008), Khangulyan et al (2008), andSierpowskaBartosik &Torres (2008). Superior conjunction is close in phase to periastron passage in LS I +61 • 303 (φ per − φ sup = 0.07 to 0.17 depending on the orbital solution).…”

Section: Discussion and Concluding Remarksmentioning

confidence: 99%

FERMI LAT OBSERVATIONS OF LS I +61°303: FIRST DETECTION OF AN ORBITAL MODULATION IN GeV GAMMA RAYS

Abdo¹,

Ackermann²,

Ajello³

et al. 2009

ApJ

136

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This Letter presents the first results from the observations of LS I +61 • 303 using Large Area Telescope data from the Fermi Gamma-Ray Space Telescope between 2008 August and 2009 March. Our results indicate variability that is consistent with the binary period, with the emission being modulated at 26.6 ± 0.5 days. This constitutes the first detection of orbital periodicity in high-energy gamma rays (20 MeV-100 GeV, HE). The light curve is characterized by a broad peak after periastron, as well as a smaller peak just before apastron. The spectrum is best represented by a power law with an exponential cutoff, yielding an overall flux above 100 MeV of 0.82 ± 0.03(stat) ± 0.07(syst) 10 −6 ph cm −2 s −1 , with a cutoff at 6.3 ± 1.1(stat) ± 0.4(syst) GeV and photon index Γ = 2.21 ± 0.04(stat) ± 0.06(syst). There is no significant spectral change with orbital phase. The phase of maximum emission, close to periastron, hints at inverse Compton scattering as the main radiation mechanism. However, previous very high-energy gamma ray (>100 GeV, VHE) observations by MAGIC and VERITAS show peak emission close to apastron. This and the energy cutoff seen with Fermi suggest that the link between HE and VHE gamma rays is nontrivial.

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“…Gamma-ray emission from TeV binaries is generally thought to originate from particle acceleration in the shock formed between the stellar wind and the pulsar wind (Tavani et al 1994;Sierpowska-Bartosik & Torres 2008;Dubus 2013). Both X-rays and gamma-rays result from synchrotron and inverse Compton scattering in the interaction region, respectively, and show a strong dependence on orbital phase.…”

Section: Introductionmentioning

confidence: 99%

NuSTAR Hard X-Ray Observation of the Gamma-Ray Binary Candidate HESS J1832–093

Mori

Gotthelf

Hailey

et al. 2017

ApJ

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We present a hard X-ray observation of the TeV gamma-ray binary candidate HESSJ1832−093, which is coincident with the supernova remnant G22.7−0.2,using the Nuclear Spectroscopic Telescope Array. Nonthermal X-ray emission from XMMUJ183245−0921539, the X-ray source associated with HESSJ1832−093, is detected up to ∼30keV and is well-described by an absorbed power-law model with a best-fit photon indexA re-analysis of archival Chandra and XMM-Newton data finds that the long-term X-ray flux increase of XMMUJ183245−0921539 is 50 % 20 40 -+ (90% C.L.), much less than previously reported. A search for a pulsar spin period or binary orbit modulation yields no significant signal to a pulse fraction limit of f 19% p < in the range 4ms P 40 < < ks. No red noise is detected in the FFT power spectrum to suggest active accretion from a binary system. While further evidence is required, we argue that the X-ray and gamma-ray properties of XMMUJ183245−0921539 are most consistent with a non-accreting binary generating synchrotron X-rays from particle acceleration in the shock formed as a result of the pulsar and stellar wind collision. We also report on three nearby hard X-ray sources, one of which may be associated with diffuse emission from a fast-moving supernova fragment interacting with a dense molecular cloud.

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Pulsar wind zone processes in LS 5039

Cited by 58 publications

References 73 publications

Gamma-ray binaries beyond one-zone models: an application to LS 5039

Gamma-ray binaries beyond one-zone models: an application to LS 5039

FERMI LAT OBSERVATIONS OF LS I +61°303: FIRST DETECTION OF AN ORBITAL MODULATION IN GeV GAMMA RAYS

NuSTAR Hard X-Ray Observation of the Gamma-Ray Binary Candidate HESS J1832–093

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