First detection of a thermonuclear X-ray burst from IGR J17445-2747 (with INTEGRAL/JEM-X)

ATel #10256; I. A. Mereminskiy, S. A. Grebenev, R. A. Krivonos, I. V. Chelovekov, R. A. Sunyaev (Space Research Institute, Moscow)
on 11 Apr 2017; 21:05 UT
Credential Certification: Sergei Grebenev (sergei@hea.iki.rssi.ru)

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During INTEGRAL observations of the Galactic Center field on April 10, 2017, its JEM-X telescope detected an X-ray burst with a FRED-like (fast ~5-s rise and long ~25-s exponential decay) shape which is characteristic of type-I X-ray bursts associated with thermonuclear explosions at the surface of neutron stars. The burst reached its peak on MJD 57853.7739. The inferred position of the burster, R.A. = 266.133 deg, Dec. = -27.784 deg (epoch 2000.0), was only 1 arcmin off the position of the weak and poorly studied source IGR J17445-2747 (its soft X-ray counterpart XMMSL1 J174429.4-274609, Bird et al. 2006, Malizia et al. 2010). Presence of type-I bursts unambiguously identifies a compact object in this system as a neutron star.

The 3-10 keV flux measured near the peak of the burst was equal to 1.8x10^-8 erg/cm²/s. Assuming that the luminosity was at the Eddington level (3.8x10³⁸ erg/s) at this epoch we can restrict a distance to the source to be less than 13 kpc. The 5-sigma upper limit on its persistent flux during these observations was 1.3x10^-10 erg/cm²/s in the same band.