IGR J08408-4503

Other name = (?)

Type Spectral type Radio Counterpart Infrared/Optical Counterpart
R.A. (J2000) Dec. (J2000) References R.A. (J2000) Dec. (J2000) References
Supergiant Fast XRT 0 8.5Ib HD 74194 = LM Vel (?) Gotz et al. 2006 Atel 813
Published Papers
Miscellaneous :
Gotz et al. 2006 ATel 813:
  • 20-40 keV peak flux of 250 mCrab
  • HD 74194 is a 7th Mag O star @1.7 kpc => Xray luminosity 1036erg/s
  • Candidate Supegiant fast XRT
  • peculiar GRB can't be completely ruled out
Mereghetti et al. 2006 ATel 814:
  • outburst lasting 2 hours in July 2003
  • peak flux of 6 x 10-10 erg/s/cm2
Masetti et al. 2006 ATel 815:
  • Analysis of ESO archival spectra of HD 74194 => Hα emission with EW 1 Angstrom
  • => HeI absorption at 6675 and 7065 A
  • this indicates HD 74194 is the optical counterpart to IGR J08408-4503 which confirms the supergiant FSXT nature
Brandt et al. 2006 ATel 817:
  • Refined position => strenghtens the association with HD 74194
  • Alhtough several other candidates: finding chart available here
Kennea & Campana 2006 ATel 818:
  • Refined position => confirms the association with HD 74194
  • Source at 3 kpc => L0.5-10 keV=2x1032 erg/s
  • probable quiescent emission from X-ray source rather than emission from the star
Barba, Gamen and Morrell 2006 ATel 819:
  • HD 74194 is a O 8.5Ib (Walborn 1973)
  • Change of Halpha line profile from double peak to P cygni
  • SFXT Similar to IGR J17544-2619
Gotz et al. 2007 ApJL:
  • Analysis of 3 flares detected up to 2007 with Swift and INTEGRAL
  • Spectra during flares is power law like with a high Ecut, and absorption (NH=~1021 cm-2, Ecut~15 keV, Gamma~0)
  • Orbital period of 1 year, spin period of hours and B~1013 G, based on donor star parameters and wind accretion conditions.
Leyder et al. 2007 A&A:
  • INTEGRAL ISGRI/JEM-X spectra: broken power law break energy of 14 keV or comptt kTe=7 keV τ=4
  • Swift => 2-10 keV flux of 3.4e-13 erg/cm2/s but most of the detected counts have an energy smaller than 1.5 keV
  • distance to the source of 2.7 kpc.
  • orbital separation of > 1013 cm
Mangano et al. 2008 ATel 1727:
  • Triggered Swift/BAT on 2008-09-21 at 07:55:08 UT.
  • Light curve is constant until T+730s.
  • Spectrum (same time interval) well represented by a powerlaw with an exponential cutoff, with Γ=1.3 ,Ecut=22.7 keV
  • Simple power law gives Γ=2.87 =>acceptable fit too
  • Swift/XRT light curve: bright flare with a flat top phase that lasts about 1 ks => spectrum well fitted by an absorbed powerlaw with a Γ=0.85 and NH=2.9 x1021 cm-2
  • 5 ks later decay by a factor of 40 in count rate=> absorbed powerlaw with Γ=0.8 and NH=3.7 x1021 cm-2
Romano et al. 2008 MNRAS:
  • Swift obs of 2 outbursts: no significant (>3sig) variations of the hardness ratio in 2006, but source gets softer with increasing luminosity in 2008
  • 2008 outburst <=> multiple flares each exceding 1e36erg/s
  • Two outbursts show significantly different spectral parameters: value of the cut-off energy during the 2006 outburst suggest B~1e12 G (lower than previously suggested)
  • During the 2008 outburst definite evolution of the absorbing column density along the outburst
  • Inter-flare spectrum much harder than the quiescent spectrum => accretion of the inter-clump medium occurs => density contrast of at least 1e3 in the wind of the supergiant
  • Clump-accretion: flare duration of 500s =>distance ~1e13 cm from companion, which implies a period of 35 days.
  • 2008 outburst does not occur in an integer multiple of the 35 days orbital cycle
  • Disk equatorial wind model of Sidoli and collaborators (<=>"double periodicity" of outbursts), with P=11 and 24 days all outburst can be accounted for.
  • Results suggestive of an ehanced equatorial wind from the supergiant, which is inclined wrt equatorial plane of the system
Sidoli et al. 2009 MNRAS:
  • spectra well fitted with models of cut off power law or power law with black body emission with little absorption
  • Seems to be clearly two population of photons, as a fit with a bmc model need the addition of a black body to account for soft X-ray emission at 0.3 keV.
Bozzo et al. 2010 (A&A):
  • XMM analysis during quiescence
  • Quiescent emission composed of multiple flares occuring after period of faint X-ray emission.
  • Hardness ratio and the intensity are positively correlated
  • Spectral analysis => soft component below 2 keV, in addition to a standard (cutoff) power law with absorption
  • Excess well represented by either a black body or thermal plasma model
  • Thermal plasma could be the X-ray emission due to shocks in the wind of the supergiant companion.
Sidoli et al. 2010 (MNRAS):
  • Suzaku observations during a long low intensity state
  • 3 different periods: low intensity stateis well represented by a thermal emission probably arising from the companion and a power law both undergoing Galactic absorption.
  • 2 other states <=> flares, well represented by locally absorbed powerlaw (in addition to the thermal plasma), with spectral consistent parameters
  • At very low luminosity the source still accretes matter
  • Calculations about clump mass and density are also presented
Romano et al. 2014(A&A):
  • Study of long term Swift/XRT monitoring
  • Behaviour similar to other SFXTs with 67% inactivity duty cycle, and a dynamic range of ~7400 during bursts
  • Two distinct populations of flares, which seems to be a ubiquitous property of extreme SFXTs
  • No correlation between duty cycle and orbital period

Last updated 5 march 2015

Jerome Rodriguez