IGR J16418-4532

Other name =

Type Spin P. / Orb. P
Super Orb. P
Radio Counterpart Infrared Counterpart
R.A. (J2000) Dec. (J2000) References (position) R.A. (J2000) Dec. (J2000) References (position)
HMXB Pulsar
SFXT candidate
1212s / 3.74d
14.6842 d
2MASS J16415078-4532253 Walter et al. 2006
Published Papers
Miscellaneous :
Sguera et al. 2006 :
  • Behaviour similar to Fast X-ray Transient
  • Suggest High mass companion
  • peak flux 80 mCrab (20-30 keV)
Corbet et al. 2006, Atel 779:
  • 3.753+-0.004 days modulation in RXTE/ASM and Swift/BAT
  • possible total eclipse
  • possible supergiant companion
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
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
Rahoui et al. 2008:
  • Medium infrared observations
  • SED fitting => AV=14.5
  • Obscuring material contributes little to MIR spectrum
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
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.
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
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
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
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
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%.
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)

Last updated 8 Nov. 2013

Jerome Rodriguez