Monthly Notices of the Royal Astronomical Society
We report on a recent bright outburst from the new X-ray binary transient MAXI J1631- 479, observed in January 2019. In particular, we present the 30-200 keV analysis of spectral transitions observed with INTEGRAL/IBIS during its Galactic plane monitoring program. In theMAXI and BAT monitoring period, we observed two different spectral transitions between the high/soft and low/hard states. The INTEGRAL spectrum from data taken soon before the second transition is best described by a Comptonized thermal component with a temperature of kTe ∼30 keV and a high-luminosity value of L2-200 keV ∼ 3 × 1038 erg-1 (assuming a distance of 8 kpc). During the second transition, the source shows a hard, power-law spectrum. The lack of high energy cut-off indicates that the hard X-ray spectrum fromMAXI J1631-479 is due to a non-thermal emission. Inverse Compton scattering of soft X-ray photons from a non-thermal or hybrid thermal/non-thermal electron distribution can explain the observed X-ray spectrum although a contribution to the hard X-ray emission from a jet cannot be determined at this stage. The outburst evolution in the hardness-intensity diagram, the spectral characteristics, and the rise and decay times of the outburst are suggesting that this system is a black hole candidate.
Chemistry, Physics, and Astronomy
Fiocchi, M., Onori, F., Bazzano, A., Bird, A. J., Bodaghee, A., Charles, P. A., Lepingwell, V. A., Malizia, A., Masetti, N., Natalucci, L., & Ubertini, P. (2020). Evolution of MAXI J1631-479 during the January 2019 outburst observed by INTEGRAL/IBIS. Monthly Notices of the Royal Astronomical Society, (3), 3657-3661.