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| Miscellaneous :
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Sguera et al. 2006 :
- Behaviour similar to Fast X-ray Transient
- Suggest High mass companion
- peak flux 80 mCrab (20-30 keV)
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Corbet et al. 2006, Atel 779:
- 3.753+-0.004 days modulation in RXTE/ASM and Swift/BAT
- possible total eclipse
- possible supergiant companion
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Walter et al. 2006:
- pulse period of 1246+-100 s in XMM (not seen in ISGRI)
- possible soft excess and marginal K-alpha line (EW < 34 eV)
- NH = 10.0(+-1.2)x1022 at/cm2
- IR counterpart (2.4 arcsec away) has a K-band magnitude of 11.5
- unabsorbed flux (2-100 keV) is 1.3x10-10 ergs/cm2/s
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Chaty et al. 2008: - Near infrared observations
- 4 Optical candidate counterparts, brightest (2MASS source)
is favoured
- J=14.03, H=16.62, Ks=11.61
- SED fitting => Tstar32800 K
- suggest an O/B star
- d=13 kpc in case of a sg star
- sg HMXB consistent with position in Corbet diagram
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Rahoui et al. 2008:
- Medium infrared observations
- SED fitting => AV=14.5
- Obscuring material contributes little to MIR spectrum
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Romano et al. 2011 ATel 3174:
- Swift/XRT observation
- Light curve shows decaying portion of a flare that reached 3
counts/s, with a dynamic range of about 70.
- Spectrum: absorbed power-law with Γ= 2.0 NH=8 x1022 cm-2
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Romano et al. 2012 (MNRAS):
- Swift monitoring
- X-ray position refined & confirm association to the previously proposed IR counterpart
- Analysis of the source's eclipse => confirm the supergiant nature
of the companion
- In the context of the accretion of spherically symmetric clumpy wind =>masses for the clumps
from 5e16 to 1e21 g
- X-ray bahaviour of the source suggests that it is an intermediate
SFXT.
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Sidoli et al. 2012 (MNRAS):
- 40-ks XMM-Newton observation performed on Feb. 23, 2011
- Strong variability > two orders of magnitudes, several bright flares of different durations (few hundreds -> few thousands of s), sometimes with quasi-periodic behavior
- Pulse period of 1212+/-6 s => slowly rotating neutron star
- Spectrum softer and more absorbed during low luminosity periods (than during the flares)
- Soft excess below 2 keV (cumulative flares spectrum) => possibly due to ionized wind material at a distance similar to the neutron star accretion radius
- All these results suggest transitional accretion regime between pure wind accretion and full Roche-lobe overflow
- Discussion on transitonal regime to explain the behavior of this and, possibly, other SFXTs with short orbital periods
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Wang & Chang 2012 (A&A):
- Study retrograde wind accretion scenario
- => spin and orbital period => R corrotation ~ 1.2e10 cm and source is a retrograde accretor
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Drave et al. 2013 (MNRAS):
- Combined INTEGRAL and XMM-Newton observations targeting the region of X-ray eclipse
- Discovery of 19 non-reported outburst in INTEGRAL archival observations
- Prominent Fe emission in XMM data during the eclipse
- Supergiant mass loss rate estimated to 2.3-3.8 e-7 Msun/year
- post-eclipse soft X-ray obs => X-ray pulsations, period of flaring activity,
variations of NH, and first discovery of dips/off states
- Dips interpreted as transition between Compton cooling dominated and radiative
cooling dominated subsonic accretion regimes => In this case the B field would be of the order of 1E14 G
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Corbet et al. 2013 ATel 5126 (see also ApJ paper):
- SuperOrbital modulation found at a period 14.7 days in Swift/BAT data
- Light curve folded on this period <=> approximately sinusoidal modulation
- Sine wave fit => Tmax = MJD 55994.6 +/- 0.4 + n x 14.730 +/- 0.006 (Tmax is the time of maximum flux)
- A=(Fmax - Fmin)/(Fmean ~ 70%
- Ratio Psuperorb/Porb~ 3.9 similar to other wind accretion HXMB with superorbital periods
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Drave et al. 2013 ATel 5131:
- Confirmation of SuperOrbital modulation with INTEGRAL at 14.6842 d
- Folded light curve (on IBIS profile) => approximately sinusoidal envelope, superimposed with a
multi-peaked structure
- Amplitude of ~130%.
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Coleiro et al. (2013) :
- NTT/Sofi NIR Spectroscopy
- Wide Br(7-4) and weak He I emission lines, and He I in absorption
- BN0.5Ia companion (although X-shooter results may suggest 09.5I type)
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