INTEGRAL observation of GRS 1739-278 in outburst

E. Filippova*, E. Kuulkers, J. Alfonso-Garzon, V. Beckmann, A. J. Bird, S. Brandt, J. Chenevez, M. Del Santo, A. Domingo, K. Ebisawa, P. G. Jonker, P. Kretschmar, C. B. Markwardt, T. Oosterbroek, A. Paizis, K. Pottschmidt, C. Sanchez-Fernandez, R. Wijnands, Enrico Bozzo, C. Ferrigno

*Corresponding author for this work

Research output: Other contributionNet publication - Internet publicationResearch


During the Galactic bulge monitoring observation (Atel #438) performed on 2014 March 19 from 11.00 to 14:42 (UTC), the black-hole candidate GRS 1739-278 (ATel #5986) was also seen by INTEGRAL.

The source is detected by IBIS/ISGRI up to an energy of about 200 keV. The estimated ISGRI flux is 143+/-2 mCrab in the 18-40 keV energy band and 166+/-2 mCrab in the 40-100 keV energy band. The fluxes estimated from JEM-X are 60+/-4 mCrab in the 3-10 keV energy band and 104+/-8 mCrab in the 10-20 keV energy band.

Its averaged broad-band (3-200 keV) spectrum, extracted by using all available ISGRI and JEM-X data (total exposure time 12.6 ks), could be roughly described with a cut-off power-law model. The measured photon index is 1.4+/-0.2 and the energy cut-off is 90(-20+40) keV (we fixed the absorption column density to the Galactic value expected in the direction of the source, i.e. 0.8E22 cm^-2). The 3-200 keV X-ray flux derived from the spectral fit is 5E-9 ergs/cm^2/s (not corrected for absorption).

This spectral shape is reminiscent of that displayed by black-hole candidates in the canonical hard state.

Further observations of the source with INTEGRAL are planned for March 28.
Original languageEnglish
Publication date20 Mar 2014
Publication statusPublished - 20 Mar 2014
SeriesThe Astronomer's telegram
NumberATel #5991


  • X-ray
  • Black hole
  • Transient


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