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IGR J05414-6858 detected in X-ray outburst with SWIFT

ATel #3537; R. Sturm, F. Haberl, W. Pietsch (Max-Planck-Institut fuer extraterrestrische Physik), S. Immler (NASA/CRESST/GSFC)
on 9 Aug 2011; 15:02 UT
Credential Certification: Richard Sturm (rsturm@mpe.mpg.de)

Subjects: X-ray, Binary, Neutron Star, Transient

We report the re-detection of IGR J05414-6858 in the Large Magellanic Cloud (LMC) with SWIFT during the SWIFT LMC survey (PI Immler) observation 7 from 2011 Aug. 5, 15:28 to Aug. 6, 22:27 UT. IGR J05414-6858 was discovered with INTEGRAL on 2010 Jun. 6-14 (ATEL #2695). In a Swift follow-up observation on 2010 Jun. 25, the source was detected (ATEL #2696) and identified as Be-X-ray Binary (ATEL #2704). An additional Swift observation was performed on 2011 Jun. 30. To model the X-ray spectra we used a power-law model with photoelectric absorption. The Galactic column density was fixed to 6x1020 cm-2 with solar abundances. An additional source intrinsic and/or LMC column density with abundances set to 0.5 solar for elements heavier than helium was a free parameter in the fit. A joint fit to the spectra of all three SWIFT observations results in a LMC column density of (2.3 ± 1.7)x1021 cm-2 and a photon index of 0.83 ± 0.17. Net counts, detected fluxes and unabsorbed luminosities for a LMC distance of 50 kpc in the (0.2-10.0) keV band are given in the following table:

   
Date           Exp [s]   Cts        Flux [10-12 erg cm-2 s-1]    L [1036 erg s-1] 
2010 Jun. 25   3920      221         5.844 (5.69 -  5.79)       1.85 
2010 Jun. 30   5202      540        10.076 (9.89 - 10.05)       3.19 
2011 Aug.  5   3349       40         3.210 (3.01 -  3.06)       1.02 
In 2010 the outburst has lasted for more than 20 days, suggesting a type II outburst of the Be system. Further monitoring of the 2011 outburst will help to decide if the source is undergoing another type II outburst.