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The Supergiant Fast X-ray Transient with the shortest orbital period: Suzaku observes one orbit in IGRJ16479-4514

2013/02/07 by L. Sidoli, Sidoli, L., P. Esposito +15
Engineering · Physics and Astronomy · #Astronomical Observations and Instrumentation #Astrophysical Phenomena and Observations #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE) #Mechanics and Biomechanics Studies #astro-ph.GA #astro-ph.HE

paper · pdf · doi:10.48550/arxiv.1302.1702

Proceedings of "An INTEGRAL view of the high-energy sky (the first 10 years)" the 9th INTEGRAL Workshop, October 15-19, 2012, Paris, France, in Proceedings of Science (INTEGRAL 2012), Eds. A. Goldwurm, F. Lebrun and C. Winkler, (http://pos.sissa.it/cgi-bin/reader/conf.cgi?confid=176), id: PoS(INTEGRAL 2012)034

arxiv created 2013/02/07 · openalex publication_date 2013/02/07 · arxiv updated 2013/02/08 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28

Abstract

The eclipsing hard X-ray source IGR J16479-4514 is the Supergiant Fast X-ray Transient (SFXT) with the shortest orbital period (3.32 days). This allowed us to perform a 250 ks long X-ray observation with Suzaku in 2012 February, covering most of its orbit, including the eclipse egress. Outside the eclipse, the source luminosity is around a few 1E34erg/s. The X-ray spectrum can be fit with an absorbed power law together with a neutral iron emission line at 6.4 keV. The column density is constant at 1E23 cm-2 outside the X-ray eclipse. During the eclipse it is lower, consistent with a scattering origin for the low X-ray emission during the eclipse by the supergiant companion wind. The scattered X-ray emission during the X-ray eclipse is used to directly probe the density of the companion wind at the orbital separation, resulting in 7E-14 g/cm3, which translates into a ratio Mdotw/vterminal = 7E-17 solar masses/km of the wind mass loss rate to the wind terminal velocity. This ratio, assuming reasonable terminal velocities in the range 500-3000 km/s, translates into an accretion luminosity two orders of magnitude higher than that observed. We conclude that a mechanism reducing the accretion rate onto the compact object is at work, likely due to the neutron star magnetosphere.

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