English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We report on a 250 ks long X-ray observation of the supergiant fast X-raytransient (SFXT) IGR J16479-4514 performed with Suzaku in 2012 February. About80% of the short orbital period (Porb=3.32 days) was covered as continuously aspossible for the first time. The source light curve displays variability ofmore than two orders of magnitude, starting with a very low emission statelasting the first 46 ks (1E-13 erg/cm2/s, 1-10 keV), consistent with being dueto the X-ray eclipse by the supergiant companion. The transition to theuneclipsed X-ray emission is energy dependent. Outside the eclipse, the sourcespends most of the time at a level of (6-7)x10^-12 erg/cm2/s punctuated by twostructured faint flares with a duration of about 10 and 15 ks. Remarkably, thefirst faint flare occurs at a similar orbital phase of the bright flarespreviously observed in the system. This indicates the presence of aphase-locked large scale structure in the supergiant wind, driving a higheraccretion rate onto the compact object. The scattered component visible duringthe X-ray eclipse allowed us to directly probe the wind density at the orbitalseparation, resulting in rho=7E-14 g/cm3. Assuming a spherical geometry for thesupergiant wind, the derived wind density translates into a ratioMdot_w/v_terminal = 7E-17 solar masses/km which, assuming terminal velocitiesin a large range 500-3000 km/s, implies an accretion luminosity two orders ofmagnitude higher than that observed. As a consequence, a mechanism is at workreducing the mass accretion rate. Different possibilities are discussed.

A Suzaku X-ray observation of one orbit of the supergiant fast X-ray transient IGR J16479-4514