Non-Thermal Emission from Early-Type Binaries

Rauw, Grégor

doi:10.1007/978-1-4020-2256-2_5

Cited by 6 publications

(2 citation statements)

References 55 publications

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“…White and Becker (1983); Abbott et al (1984), or Rauw (2004) for a review). The main characteristics of such a radio emission disagreeing with the classical thermal emission discussed above are the following:…”

Section: Introductionmentioning

confidence: 99%

“…However, some of the massive stars observed in the radio domain present significant deviations from this well-defined behaviour (see e.g. White and Becker (1983); Abbott et al (1984), or Rauw (2004) for a review). The main characteristics of such a radio emission disagreeing with the classical thermal emission discussed above are the following:…”

Section: Introductionmentioning

confidence: 99%

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Non-thermal emission processes in massive binaries

Becker

2007

Astron Astrophys Rev

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In this paper, I present a general discussion of several astrophysical processes likely to play a role in the production of non-thermal emission in massive stars, with emphasis on massive binaries. Even though the discussion will start in the radio domain where the non-thermal emission was first detected, the census of physical processes involved in the non-thermal emission from massive stars shows that many spectral domains are concerned, from the radio to the very high energies.First, the theoretical aspects of the non-thermal emission from early-type stars will be addressed. The main topics that will be discussed are respectively the physics of individual stellar winds and their interaction in binary systems, the acceleration of relativistic electrons, the magnetic field of massive stars, and finally the non-thermal emission processes relevant to the case of massive stars. Second, this general qualitative discussion will be followed by a more quantitative one, devoted to the most probable scenario where nonthermal radio emitters are massive binaries. I will show how several stellar, wind and orbital parameters can be combined in order to make some semiquantitative predictions on the high-energy counterpart to the non-thermal emission detected in the radio domain.These theoretical considerations will be followed by a census of results obtained so far, and related to this topic. These results concern the radio, the visible, the X-ray and the γ-ray domains. Prospects for the very high energy γ-ray emission from massive stars will also be addressed. Two particularly interesting examples -one O-type and one Wolf-Rayet binary -will be considered in details. Finally, strategies for future developments in this field will be discussed.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Non-thermal emission processes in massive binaries

Becker

2007

Astron Astrophys Rev

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Gamma rays from colliding winds of massive stars

Reimer

Pohl

2007

The Multi-Messenger Approach to High-Energy Gamma-Ray Sources

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Colliding winds of massive binaries have long been considered as potential sites of non-thermal highenergy photon production. This is motivated by the detection of non-thermal spectra in the radio band, as well as by correlation studies of yet unidentified EGRET γ-ray sources with source populations appearing in star formation regions.This work re-considers the basic radiative processes and its properties that lead to high energy photon production in long-period massive star systems. We show that Klein-Nishina effects as well as the anisotropic nature of the inverse Compton scattering, the dominating leptonic emission process, likely yield spectral and variability signatures in the γ-ray domain at or above the sensitivity of current or upcoming gamma ray instruments like GLAST-LAT. In addition to all relevant radiative losses, we include propagation (such as convection in the stellar wind) as well as photon absorption effects, which a priori can not be neglected.The calculations are applied to WR 140 and WR 147, and predictions for their detectability in the γ-ray regime are provided. Physically similar specimen of their kind like WR 146, WR 137, WR 138, WR 112 and WR 125 may be regarded as candidate sources at GeV energies for near-future γ-ray experiments.Finally, we discuss several aspects relevant for eventually identifying this source class as a γ-ray emitting population. Thereby we utilize our findings on the expected radiative behavior of typical colliding wind binaries in the γ-ray regime as well as its expected spatial distribution on the γ-ray sky.

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A multi-epochXMM-Newtoncampaign on the core of the massive Cygnus OB2 association

Rauw

2011

A&A

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Context. Cyg OB2 is one of the most massive associations of O-type stars in our Galaxy. Despite the large interstellar reddening towards Cyg OB2, many studies, spanning a wide range of wavelengths, have been conducted to more clearly understand this association. X-ray observations provide a powerful tool to overcome the effect of interstellar absorption and study the most energetic processes associated with the stars in Cyg OB2. Aims. We analyse XMM-Newton data to investigate the X-ray and UV properties of massive O-type stars as well as low-mass pre-main sequence stars in Cyg OB2. Methods. We obtained six XMM-Newton observations of the core of Cyg OB2. In our analysis, we pay particular attention to the variability of the X-ray bright OB stars, especially the luminous blue variable candidate Cyg OB2 #12. Results. We find that X-ray variability is quite common among the stars in Cyg OB2. Whilst short-term variations are restricted mostly to low-mass pre-main sequence stars, one third of the OB stars display long-term variations. The X-ray flux of Cyg OB2 #12 varies by 37%, over timescales from days to years, whilst its mean log L X L bol amounts to −6.10. Conclusions. These properties suggest that Cyg OB2 #12 is either an interacting-wind system or displays a magnetically confined wind. Two other X-ray bright O-type stars (MT91 516 and CPR2002 A11) display variations that suggest they are interacting wind binary systems.

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Non-Thermal Emission from Early-Type Binaries

Cited by 6 publications

References 55 publications

Non-thermal emission processes in massive binaries

Non-thermal emission processes in massive binaries

Gamma rays from colliding winds of massive stars

A multi-epochXMM-Newtoncampaign on the core of the massive Cygnus OB2 association

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