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          Institute: MPI für Kernphysik     Collection: High-Energy Astrophysics     Display Documents

ID: 317879.0, MPI für Kernphysik / High-Energy Astrophysics
Exploring the connection between the stellar wind and the non-thermal emission in LS 5039
Authors:Bosch-Ramon, Valenti; Motch, Christian; Ribo, Marc; Lopes de Oliveria, Raimundo; Janot-Pacheco, Eduardo; Negueruela, Ignacio; Paredes, Josep M.; Martocchia, Andrea
Date of Publication (YYYY-MM-DD):2007-10
Title of Journal:Astronomy & Astrophysics
Journal Abbrev.:A&A
Issue / Number:2
Start Page:545
End Page:550
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:LS 5039 has been observed with several X-ray instruments so far. The source presents X-ray variability at orbital timescales in flux and photon index. The system harbors an O-type main sequence star with moderate mass loss. At present, the link between the X-rays and the stellar wind is unclear. New XMM-Newton observations have been performed around periastron and apastron passages in September 2005, when the stellar wind activity was apparently higher. April 2005 Chandra observations on LS 5039 are also revisited. Moreover, a compilation of Halpha EW data obtained since 1992, from which the stellar mass loss evolution can be approximately inferred, is carried out. XMM-Newton observations show higher and harder emission around apastron than around periastron. No signatures of thermal emission or a reflection iron line indicating the presence of an accretion disk are found in the spectrum, and the hydrogen column density (NH) is compatible with being the same in both observations and consistent with the interstellar value. 2005 Chandra observations show a hard X-ray spectrum, and possibly high fluxes. The Halpha EW shows yearly variations of a ~ 10%, and does not seem to be correlated with X-ray fluxes obtained at similar phases, unlike it would be expected in the wind accretion scenario. 2005 XMM-Newton and Chandra observations are consistent with
2003 RXTE/PCA results. The constancy of the NH seems to imply that either the X-ray emitter is located at >~ 1012 cm from the compact object, or the real N_H is 3-27 times smaller than the one predicted by a spherical symmetric wind model. We suggest that the multiwavelength non-thermal emission of LS 5039 is related to the radio jets and unlikely produced inside the binary system.
External Publication Status:published
Document Type:Article
Affiliations:MPI für Kernphysik/Group of W. Hofmann/High Energy Astrophysics (F. Aharonian)
External Affiliations:Observatoire Astronomique, rue de l'Université 11, Strasbourg 67000, France
Departament d'Astronomia i Meteorologia, Universitat de Barcelona, c/Martí i Franquès 1, 08028 Barcelona, Catalonia, Spain
Universidade de São Paulo, Instituto de Astronomia, Geofísica e Ciéncias Atmosféricas - IAG, Departamento de Astronomia, Rua do Matao, 1226 - 05508-900 São Paulo, Brazil
Dpto. de Física, Ingeniería de Sistemas y Teoría de la Señal, Universidad de Alicante, Apdo. 99, 03080 Alicante, Spain
Istituto Nazionale di Astrofisica, Via del Fosso del Cavaliere 100, 00133 Roma, Italy
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