IGR J16195-4945

Other name = AX J161929-4945

Type Spectral type/Temp.
Orb. Period / Spin Period
Radio Counterpart Infrared Counterpart
R.A. (J2000) Dec. (J2000) References (position) R.A. (J2000) Dec. (J2000) References (position)
(probable)Neutron star/sgHMXB

Candidate Fast XRT
ON9.7 Iab /
3.945 d /
2MASS J16193220-4944305 Tomsick et al. 2006
Published Papers
Miscellaneous :
Sidoli et al. 2005 :
  • NH=~12 x 1022 cm-2
  • Hard X-ray spectrum (photon index~0.6) as ssen by ASCA
Sguera et al. 2006:
  • Behaviour similar to Fast X-ray Transient
  • Suggest High mass companion
  • peak flux 17-35 mCrab (20-40 keV)
Tomsick et al. 2006 :
  • Chandra position rules out association with HD 146628 (1.2' away).
  • Column density is ~7x1022 at/cm2 and Gamma~0.5.
  • Spectral type of optical companion (J-band magnitude of 13.57(3)) is compatible with an O, B or A giant so the system is a HMXB.
  • Distance estimated at 3-15 kpc, so 0.3-10 keV luminosity is ~1.4x1034 ergs/s (for d=5kpc).
Tovmassian et al. 2006 ATel 804:
  • Spectrum is consistent with that of a late F-type star, and shows absorption lines but none of the emission lines that are expected from an X-ray binary system.
  • Source reddening is too low to be compatible with the large extinction that was recently reported by Tomsick et al. (2006).
  • Therefore, this object is a foreground dwarf star and not the giant star that is expected to be the likely counterpart.
Rahoui et al. 2008:
  • Not detected in medium infrared observations
  • SED fitting based on 2MASS and GLIMPSE data => AV=15.5, T*=23800 K
  • Need for an additional component to sit spectra: T=1160K
  • Temperature of star compatible with an O/B sg, best fit => B1 distance from 3.1 to 9.8 kpc if source is main seq, sub giant or super giant
Morris et al. 2009:
  • Suzaku observations
  • Observation is separated into several intervals due to flare
  • Heavily absorbed HMXB
  • Mention the possible presence of a disk around the donor star through models of accretion=>they can estimate a tentative orbital period of about 16 days from modelisation.
Coleiro et al. (2013) :
  • NTT/Sofi NIR Spectroscopy
  • H-band spectrum shows very few lines => consistent with Sg late O-type star
  • Analysis of other lines => ON9.7 Iab
Cusumano et al. (2016) :
  • Analysis of long term Swift monitoring
  • BAT ligth curve => modulation at 3.945d interpreted as the orbital period of the system
  • Folded light curve shows narrow eclipse lasting 3.5% of the orbit. => semi-major orbital axis 31 RSun, inclination 55-60°
  • XRT+BAT spectrum => absorbed (NH=7e22 cm-2) power law (Γ=0.5) with high energy cut-off (14 keV)

Last updated 5 Feb. 2016

Jerome Rodriguez