Probing large-scale wind structures in Vela X–1 using off-states with INTEGRAL
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Título: | Probing large-scale wind structures in Vela X–1 using off-states with INTEGRAL |
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Autor/es: | Sidoli, Lara | Paizis, Adamantia | Fürst, Felix | Torrejon, Jose M. | Kretschmar, Peter | Bozzo, Enrico | Pottschmidt, Katja |
Grupo/s de investigación o GITE: | Astronomía y Astrofísica |
Centro, Departamento o Servicio: | Universidad de Alicante. Departamento de Física, Ingeniería de Sistemas y Teoría de la Señal | Universidad de Alicante. Instituto Universitario de Física Aplicada a las Ciencias y las Tecnologías |
Palabras clave: | Stars: neutron | X-rays: binaries | X-rays: individual: Vela X–1 |
Área/s de conocimiento: | Física Aplicada |
Fecha de publicación: | 21-feb-2015 |
Editor: | Royal Astronomical Society |
Cita bibliográfica: | Monthly Notices of the Royal Astronomical Society. 2015, 447(2): 1299-1303. doi:10.1093/mnras/stu2533 |
Resumen: | Vela X–1 is the prototype of the class of wind-fed accreting pulsars in high-mass X-ray binaries hosting a supergiant donor. We have analysed in a systematic way 10 years of INTEGRAL data of Vela X–1 (22–50 keV) and we found that when outside the X-ray eclipse, the source undergoes several luminosity drops where the hard X-rays luminosity goes below ∼3 × 1035 erg s−1, becoming undetected by INTEGRAL. These drops in the X-ray flux are usually referred to as ‘off-states’ in the literature. We have investigated the distribution of these off-states along the Vela X–1 ∼ 8.9 d orbit, finding that their orbital occurrence displays an asymmetric distribution, with a higher probability to observe an off-state near the pre-eclipse than during the post-eclipse. This asymmetry can be explained by scattering of hard X-rays in a region of ionized wind, able to reduce the source hard X-ray brightness preferentially near eclipse ingress. We associate this ionized large-scale wind structure with the photoionization wake produced by the interaction of the supergiant wind with the X-ray emission from the neutron star. We emphasize that this observational result could be obtained thanks to the accumulation of a decade of INTEGRAL data, with observations covering the whole orbit several times, allowing us to detect an asymmetric pattern in the orbital distribution of off-states in Vela X–1. |
Patrocinador/es: | We acknowledge support from ISSI through funding for the International Team on ‘Unified View of Stellar Winds in Massive X-ray Binaries’ (PI: S. Martínez-Nuñez). JMT acknowledges grant AYA2010-15431. LS and AP acknowledge the Italian Space Agency financial support INTEGRAL ASI/INAF agreement no. 2013-025.R.0. |
URI: | http://hdl.handle.net/10045/45958 |
ISSN: | 0035-8711 (Print) | 1365-2966 (Online) |
DOI: | 10.1093/mnras/stu2533 |
Idioma: | eng |
Tipo: | info:eu-repo/semantics/article |
Derechos: | © 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society |
Revisión científica: | si |
Versión del editor: | http://dx.doi.org/10.1093/mnras/stu2533 |
Aparece en las colecciones: | INV - Astronomía y Astrofísica - Artículos de Revistas |
Archivos en este ítem:
Archivo | Descripción | Tamaño | Formato | |
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MNRAS-2015-Sidoli-1299-303.pdf | 1,16 MB | Adobe PDF | Abrir Vista previa | |
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