INTEGRAL/JEM-X detects XMMU J174445.5-295044 in a new outburst

ATel #15236; J. Chenevez, S. Brandt, N. Lund, N. J. Westergaard (DTU Space), E. Kuulkers (ESA) on behalf of the INTEGRAL Galactic Bulge Monitoring team
on 23 Feb 2022; 12:23 UT
Credential Certification: Jerome CHENEVEZ (jerome@space.dtu.dk)

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A new season of INTEGRAL monitoring observations of the Galactic Bulge (ATel #438; Kuulkers et al. 2007, A&A, 466, 595) has started. The JEM-X instrument (3-25 keV) detects the symbiotic low-mass X-ray binary XMMU J174445.5-295044 (e.g. Bahramian et al. 2014, MNRAS 441, 640) in outburst during INTEGRAL revolutions 2470 (on 18 February 2022, between UTC 01:44 and 05:25), 2471 (19 February 2022, UTC 11:41 - 15:23), and 2472 (22 February 2022, UTC 07:31 - 13:15).

The source flux measured in JEM-X mosaic images seems to decrease as follows:
During revolution 2470, F_{(3-10 keV)} = 16 ±2 mCrab (2.5±0.3 ×10^-10 erg/cm²/s, assuming a Crab-like spectrum) and F_{(10-25 keV)} = 13 ±3 mCrab (1.5±0.3 ×10^-10 erg/cm²/s), with 12.3 ks effective exposure in the combined JEM-X1+2 mosaics.
During revolution 2471, F_{(3-10 keV)} = 5 ±2 mCrab and F_{(10-25 keV)} = 10 ±3 mCrab, with 6.6 ks effective exposure in JEM-X1 mosaics alone (JEM-X2 was not measuring at that time).
During revolution 2472, F_{(3-10 keV)} = 8 ±2 mCrab, while the source is not detected above 10 keV, leading to a 3-σ upper limit of 8 mCrab between 10-25 keV, with 12.7 ks effective exposure in the combined JEM-X1+2 mosaics.

Caveat: the above measurements are obtained with Near-Real-Time data, i.e. without a proper correction for the actual detector gain. In particular, observations during revolutions 2471 and 2472 were taken while the detectors were still warming up, which may lead to weaker flux measurements.

INTEGRAL observed XMMU J174445.5-295044 in similar conditions 10 years ago (Chenevez et al. 2012, ATel #4000), but at that time the source was only detected between 10-25 keV.
The latest detections of XMMU J174445.5-295044 were reported in 2019 by Swift/XRT (Heinke et al. 2019, ATel #12843) and by SRG/ART-XC (Mereminskiy et al. 2019, ATel #13095) at lower fluxes.

INTEGRAL will continue to monitor the Galactic Bulge (next time on 26 February) at a cadence of about one observation (12.6 ks) every revolution (2.7 days) until end of April.