SVOM/ECLAIRs detection of a thermonuclear burst from 4U 0614+091
ATel #16973; F. Cangemi (APC, France), A. Coleiro (APC, F), J.-L. Atteia (IRAP, F), N. Dagoneau (CEA, F), D. Götz (CEA, F), S. Guillot (IRAP, F), S. Schanne (CEA, F); SVOM JSWG: J.-Y. Wei (NAOC, China), B. Cordier (CEA, F), S.-N. Zhang (IHEP, C), S. Basa (LAM, F), A. Claret (CEA, F), Z.-G. Dai (USTC, C), F. Daigne (IAP, F), J.-S. Deng (NAOC, C), O. Godet (IRAP, F), A. Goldwurm (APC, F), X.-H. Han (NAOC, C), C. Lachaud (APC, F), E.-W. Liang (GXU, C), Y.-L. Qiu (NAOC, C), S. Vergani (Obs. Paris, F), J. Wang (NAOC, C), C. Wu (NAOC, C), L.-P. Xin (NAOC, C), S.-L. Xiong (IHEP, C), B. Zhang (UNLV, USA)
on 11 Jan 2025; 22:36 UT
Credential Certification: Alexis Coleiro (alexis.coleiro@u-paris.fr)
Subjects: X-ray, Binary, Neutron Star
Referred to by ATel #: 17001
On Friday December 10th at 15:58:02 UTC (Tb), the Image Trigger of the ECLAIRs telescope on-board SVOM detected a burst from the onboard-catalogue source 4U 0614+091 located at R.A. = 94.281 deg; Dec = 9.137 deg (J2000). The best detection was obtained with a signal to noise ratio of 47.4 in the 5-8 keV energy band during a 20.48 s time window starting at Tb. The light-curve transmitted showed a single peak with a fast rise time of approximately 0.5 s followed by an exponential decay-like shape during approximately 60 s in the 5-20 keV band. This observation hence suggests the detection of a thermonuclear (type I) X-ray burst of 4U 0614+091. The MXT and VT telescopes of SVOM did not perform follow-up observations, since triggers from catalogue sources currently do not request spacecraft slews.
A preliminary spectral analysis with SVOM/ECLAIRs shows that the source is significantly detected up to ~30 keV during the first 20 s of the burst. We fit the 4-50 keV spectrum with an unabsorbed black body (bbodyrad) model with a temperature of kT = 2.06 +0.08/-0.06 keV (90% confidence level) and a radius of 6 +/-5 km, in addition to a powerlaw model with a photon index of 2.1 +0.7/-0.9 (chi2 = 9.50 / 11 dof). The integrated 4-50 keV flux is about (7.3 +/-0.9)e-08 erg/s/cm^2 corresponding to a luminosity of 8.9e37 erg/s assuming a distance of 3.2 kpc.
At the end of the main peak (Tb+60s; Tb+80s), the source is still significantly detected up to an energy of about 10 keV. The 4-10 keV spectrum is well fitted (chi2 = 9.10 / 13 dof) with a single black body component with kT = 1.0 +0.3/-0.2 keV, showing evidence for a temperature decrease along the burst.
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.
