SVOM detection of the onset of a new outburst from the HMXB 4U 1416-62
ATel #17198; F. Cangemi (APC, France), A. Coleiro (APC, F), B. Cordier (CEA, F), N. Dagoneau (CEA, F), O. Godet (IRAP, F), D. Götz (CEA, F), S. Guillot (IRAP, F), T. Maiolino (LUPM, F), J. Rodriguez (CEA, F), S. Schanne (CEA, F), L. Tao (IHEP, China), W. J. Xie (NAOC, C), L. Zhang (IHEP, C)
on 20 May 2025; 17:53 UT
Credential Certification: Floriane Cangemi (cangemi@apc.in2p3.fr)
Subjects: Binary, Neutron Star
On Saturday, May 17th 2025, at 09:26:03 UTC, the SVOM/ECLAIRs (4-150 keV) coded-mask telescope detected a source associated with the Be-High Mass X-ray Binary 4U 1416-62 (aka H1417-624, 2S 1417-624) with the onboard trigger. During the observation, the estimated average count rate is about 193 cts/s in the 4-120 keV energy band. Renewed activity from this source is also confirmed with the Swift/BAT telescope light curve which clearly shows an increase of the hard X-ray flux (see https://swift.gsfc.nasa.gov/results/transients/weak/H1417-624/).
A preliminary spectral analysis with SVOM/ECLAIRs indicates that the 4-120 keV spectrum (with an exposure time of 8263 sec) is well fitted (chi2 = 31.43 / 21 dof) with an unabsorbed cutoff power law model with a photon index of Gamma = -0.4 +/- 0.6 (90% confidence level) and a cutoff energy at 9 +18/-3 keV. An emission line is also detected at 6.8 +/-0.4 keV, compatible with Iron K_alpha, and with an equivalent width of approximately 0.95 keV. The integrated fluxes measured in the 4-10 keV and 4-120 keV energy ranges are (3.3 +0.1/-2.9)e-10 ergs/cm^2/s and (1.7 +1.6/-1.2)e-09 ergs/cm^2/s respectively. At present, the flux is five times lower than the peak flux measured by NuSTAR in the 10-79 keV band during its outburst in 2018 (Gupta et al. 2019), but it continues to increase.
SVOM will continue monitoring the source during the following days. Multi-wavelength follow-up is encouraged.
The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. ECLAIRs was developed jointly by APC, CEA, CNES and IRAP. MXT has been developed jointly by CNES, CEA, IJCLab, University of Leicester and MPE.
