References of "Walter, R"
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See detailNew INTEGRAL Observations of η Carinae Close to Periastron
Leyder, J.-C.; Walter, R.; Rauw, Grégor ULg

in Astronomical Society of the Pacific Conference Series (2013, January 01)

The soft X-ray thermal emission of η Carinae varies strongly around the periastron, following the orbital period of 5.5 yr. We studied the hard X-ray non-thermal emission of η Car using new INTEGRAL ... [more ▼]

The soft X-ray thermal emission of η Carinae varies strongly around the periastron, following the orbital period of 5.5 yr. We studied the hard X-ray non-thermal emission of η Car using new INTEGRAL observations taken close to periastron. We showed that the hard X-ray emission is very likely to be associated with η Car, and not with any other source found within the INTEGRAL error circle. We also showed that the 3-σ detection during the soft X-ray minimum is consistent with a hydrogen column density that does not exceed 6×10[SUP]23[/SUP] cm[SUP]-2[/SUP]. [less ▲]

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See detailHard X-ray identification of η Carinae and steadiness close to periastron
Leyder, Jean-Christophe ULg; Walter, R.; Rauw, Grégor ULg

in Astronomy and Astrophysics (2010), 524

Context. The colliding-wind binary η Carinae exhibits soft X-ray thermal emission that varies strongly around the periastron passage. It has been found to have non-thermal emission, thanks to its ... [more ▼]

Context. The colliding-wind binary η Carinae exhibits soft X-ray thermal emission that varies strongly around the periastron passage. It has been found to have non-thermal emission, thanks to its detection in hard X-rays using INTEGRAL and Suzaku, and also in γ-rays with AGILE and Fermi. <BR /> Aims: This paper attempts to definitively identify η Carinae as the source of the hard X-ray emission, to examine how changes in the 2-10 keV band influence changes in the hard X-ray band, and to understand more clearly the mechanisms producing the non-thermal emission using new INTEGRAL observations obtained close to periastron passage. <BR /> Methods: To strengthen the identification of η Carinae with the hard X-ray source, a long Chandra observation encompassing the INTEGRAL/ISGRI error circle was analysed, and all other soft X-ray sources (including the outer shell of η Carinae itself) were discarded as likely counter-parts. To expand the knowledge of the physical processes governing the X-ray lightcurve, new hard X-ray images of η Carinae were studied close to periastron, and compared to previous observations far from periastron. <BR /> Results: The INTEGRAL component, when represented by a power law (with a photon index Γ of 1.8), would produce more emission in the Chandra band than observed from any point source in the ISGRI error circle apart from η Carinae, as long as the hydrogen column density to the ISGRI source is lower than N[SUB]H[/SUB] ≲ 10[SUP]24[/SUP] cm[SUP]-2[/SUP]. Sources with such a high absorption are very rare, thus the hard X-ray emission is very likely to be associated with η Carinae. The eventual contribution of the outer shell to the non-thermal component also remains fairly limited. Close to periastron passage, a 3-σ detection is achieved for the hard X-ray emission of η Carinae, with a flux similar to the average value far from periastron. <BR /> Conclusions: Assuming a single absorption component for both the thermal and non-thermal sources, this 3-σ detection can be explained with a hydrogen column density that does not exceed N[SUB]H[/SUB] ≲ 6 × 10[SUP]23[/SUP] cm[SUP]-2[/SUP] without resorting to an intrinsic increase in the hard X-ray emission. The energy injected in hard X-rays (averaged over a month timescale) appears to be rather constant at least as close as a few stellar radii, well within the acceleration region of the wind. [less ▲]

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See detailHard X-ray emission from eta Carinae
Leyder, Jean-Christophe ULg; Walter, R.; Rauw, Grégor ULg

in Astronomy and Astrophysics (2008), 477

Context: If relativistic particle acceleration takes place in colliding-wind binaries, hard X-rays and gamma-rays are expected through inverse Compton emission, but to date these have never been ... [more ▼]

Context: If relativistic particle acceleration takes place in colliding-wind binaries, hard X-rays and gamma-rays are expected through inverse Compton emission, but to date these have never been unambiguously detected. Aims: To detect this emission, observations of eta Carinae were performed with INTEGRAL, leveraging its high spatial resolution. Methods: Deep hard X-ray images of the region of eta Car were constructed in several energy bands. Results: The hard X-ray emission previously detected by BeppoSax around eta Car originates from at least 3 different point sources. The emission of eta Car itself can be isolated for the first time, and its spectrum unambiguously analyzed. The X-ray emission of eta Car in the 22-100 keV energy range is very hard (Gamma ~= 1 ± 0.4) and its luminosity is 7 × 10^33 erg s^-1. Conclusions: The observed emission is in agreement with the predictions of inverse Compton models, and corresponds to about 0.1% of the energy available in the wind collision. eta Car is expected to be detected in the GeV energy range. [less ▲]

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See detailThe Stavelot Massif from Cambrian to recent. A survey of the present state of knowledge
Bless, M. J. M.; Bouckaert, J.; Camelbeek, L. et al

in Annales de la Société Géologique de Belgique (1990)

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See detailPre-Permian sedimentation in NW Europe.
Bless, M.J.M.; Bouckaert, J; Conil, R et al

in Sedimentary Geology (1980), 27(1), 1-81

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