Accretion in supergiant High Mass X-ray Binaries
1 Centrum Astronomiczne im. M. Kopernika, Bartycka 18, PL-00716 Warszawa, Poland
2 ISDC & Observatoire de Genève, Université de Genève, ch. d’Ecogia 16, CH-1290 Versoix, Switzerland
3 Department of Physics, North Carolina State University, Raleigh, NC 27695-8202, USA
a e-mail: email@example.com
Published online: 8 January 2014
Supergiant High Mass X-ray Binary systems (sgHMXBs) consist of a massive, late type, star and a neutron star. The massive stars exhibits strong, radiatively driven, stellar winds. Wind accretion onto compact object triggers X-ray emission, which alters the stellar wind significantly. Hydrodynamic simulation has been used to study the neutron star - stellar wind interaction it two sgHMXBs: i) A heavily obscured sgHMXB (IGR J17252–3616) discovered by INTEGRAL. To account for observable quantities (i.e., absorbing column density) we have to assume a very slow wind terminal velocity of about 500 km/s and a rather massive neutron star. If confirmed in other obscured systems, this could provide a completely new stellar wind diagnostics. ii) A classical sgHMXB (Vela X-1) has been studied in depth to understand the origin of the off-states observed in this system. Among many models used to account for this observed behavior (clumpy wind, gating mechanism) we propose that self-organized criticality of the accretion stream is the likely reason for the observed behavior. In conclusion, the neutron star, in these two examples, acts very effciently as a probe to study stellar winds.
© Owned by the authors, published by EDP Sciences, 2014
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