2011/11/24 by L. Sidoli, Sidoli, L.
Physics and Astronomy · #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE) #Solar and Stellar Astrophysics (astro-ph.SR) #astro-ph.GA #astro-ph.HE #astro-ph.SR
paper · pdf · doi:10.48550/arxiv.1111.5747
Invited talk at the conference "The Extreme and Variable High Energy Sky", September 19-23, 2011, Chia Laguna, Sardegna (Italy). 8 pages, 3 figures, accepted for publication on PoS (PoS(Extremesky 2011)010)
arxiv created 2011/11/24 · arxiv updated 2011/11/28
Supergiant Fast X-ray Transients (SFXTs) represent the most extreme case of X-ray variability in High Mass X-ray Binaries hosting blue supergiant companions. Mainly discovered thanks to the INTEGRAL monitoring of the Galactic plane, these hard X-ray transients display dynamic ranges which can span five orders of magnitude. This intensity variability is associated with accretion onto Galactic compact objects (mostly neutron stars) through a physical mechanism which is still poorly understood. A review of the current status of our understanding on these sources is presented and discussed. Finally, I present recent XMM-Newton results about the SFXT IGRJ16418-4532, proposing that its variability behavior is due to a transitional accretion regime, intermediate between pure wind accretion and Roche Lobe Overflow. This same regime could explain the X-ray activity of other "intermediate" SFXTs with narrow orbits.