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| Miscellaneous :
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Levine et al.ATel 940:
Period of 18.55+- 0.05 d in RXTE/ASM light curve
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Sguera et al. 2007
(accepted in A&A):
- Identify 5 new outbursts in all INTEGRAL archival data
- 3-50 keV spectrum absorbed cut-off power law
- NH=9 x1022 cm-2, Gamma=1.4 and Ecut=22 keV.
- Absorbed bremsstrahlung provide good fits with Nh~7.5e22 cm-2 and kT~21.5 keV, valid for all
5 outbursts
- Discovery of a period of 18.52+-0.01 days= orbital period of the system
- Pulse period (from the JEM-X data) of 21.0526+-0.0005s with a pulse fraction of 65+-10%.
- Swift spectra absorbed power laws with Gamma=1.7 and 1.3
and NH = 6.3e22 and 4.8e22 cm-2 for the 1st and 2nd observation repsectively
- Identify an Optical counterpart from the USNO-B1.0
catalogue with magnitudes R=19.26, I=15.32, J=10.74, H=9.29, K=8.46.
- Source contains a pulsar with a spin of 21.0526s
- highly redenned Optical counterpart suggestthe source is a HMXB.
- Likely Be system by its position in a Corbet diagram
- SFXT is not ruled out
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Masetti et al. 2008:
- Optical spectroscopy is presented and detailed
- Hα in emission
- OB Giant
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Chaty et al. 2008:
- Optical and infrared observations
- 2MASS source possibly blended with another faint source
- J=10.77, H=9.21, Ks=8.39
- SED fitting => T*=22500 K, typical of B star
- d from 0.9 to 2.7 kpc if source is main sequence, sub giant or super
giant
- near IR excess => disk/wind as in massive star
- cannot conclude on sg or Be but definitely an HMXB
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Rahoui & Chaty 2008:
- Optical and near infrared observations of IGR J18483-0311.
- Spectroscopic analysis + identifications
of several emission and absorption line classify the
companion star as a B0.5 Ia supergiant.
- Not a Be X-ray binary as had been suggested before
- Fitt of the SED =>temperature of 24 600 K and estimate a distance
to the source of 3-4 kpc.
- Supergiant Fast X-ray Transient, with peculiar characteristics
- Probably has a small and
eccentric orbit.
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Giunta et al. 2009:
- XMM-Newton (orb. phase 0.52), Chandra (orb. phase 0.24) and Swift (orb. phase 0.67)
observations during quiescence
- Refined X-ray position compatible with optical counterpart
- 0.5-10 keV XMM/EPIC-PN spectrum fitted with an absorbed
power law: NH=7.7 x 1022 cm-2 and Γ=2.5
- Upper limits on equivalent widths of lines at 6.4 and 6.7 keV are
0.17 and 0.10 keV, respectively
- Swift spectrum fitted with absorbed power law: NH=6.0 x 1022 cm-2
Γ=1.4
- 3-7-sigma detection of a spin period of 21.033s from XMM/PN data with a
pulse fraction ~15% with a sinusoidal profile
- Variations in the spin period: they measure a spin-period derivative of -1.3(3)x10^-9 s/s
unknown origin for change of spin period, believe that due to light travel time effects
- Changes in the X-ray flux could be due to changes in the accretion
rate rather than due to eclipsing events
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Romano et al. 2009:
- Swift => first (nearly-)continuous observation over an entire orbital period
- Quiescent luminosity of 2.3e33 erg/s, a factor 1200 lower than the peak luminosity
- Nosignificant change in spectral parameters (other than in the blackbody
radius) wrt the orbital phase
- BB radius ~ few hundred meters =>emission occurs very near the surface (e.g. magnetic poles)
- Longterm lightcurve explained by the accretion of a homogeneous and spherically-symmetric wind
along a highly-eccentric orbit
- Large variations on short timescales <=>accretion of an isotropic clumpy wind with clumps ranging in mass from 1e18 to 5e21 g.
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Torrejón et al. 2009:
- Optical spectroscopy
- Companion is a Sg B0.5-B1 star luminosity class likely Iab
- =>distance 2.8 kpc
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Sguera et al. 2010:
- Archival XMM and INTEGRAL observations
- XMM observation taken at the lowest X-ray flux
ever reported => quiescent emission.
- Absorbed black body to represent spectrum
- Overall XMM+INTEGRAL spectrum well fitted by an absorbed black body with
a power law component: kT=1.40 keV, Gamma=2.0, NH=3.4 x 1022 cm-2.
- Possible detection of a cyclotron emission feature at 3.3 keV
- =>Leads to B~3-4e11 G,compatible with value derived with alternative
method.
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Wang & Chang 2012 (A&A):
- Study retrograde wind accretion scenario
- => spin and orbital period => R corrotation ~ 0.16e9 cm and source is a retrograde propeller
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Ducci et al. 2013 (A&A):
- INTEGRAL observations over 2003-2010
- 15 outburst including 7 never reported before detected
- Refined timing analysis => no significant periodicity in the INTEGRAL obs.
- Re-analysis of XMM data -> 21s prob. due to statistical fluctuations
- Spectra in outburst well fitted by thermal and bulk Comptonization of bb seed photons.
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Sguera et al. 2015 (MNRAS):
- INTEGRAL archival + new XMM-Newton observations
- A new unusually long X-ray activity (3-60 keV) discovered, lasted about 60% (11 d) of the orbit of
the system
- Re-analysis of INTEGRAL data confirm non-significance of a potential hard tail (> 80 keV)
- XMM did not detect strong activity at close to periastron, but standard intermediate state, with L~ 3e33 erg/s
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