Evolution of MAXI J1631–479 during the January 2019 outburst observed by INTEGRAL/IBIS. Issue 3 (11th January 2020)

• Record Type: Journal Article
• Authors: 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
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 492:Issue 3(2020)
• Page Start: 3657
• Page End: 3661
• Publication Date: 2020-01-11
• Subjects: radiation mechanisms: non-thermal -- stars: black holes -- stars: individual: MAXI J1631–479 -- stars: neutron -- X-rays: binaries; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/staa068
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: 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 the MAXI 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 $L_{2-200\, \mathrm{keV}}\sim 3\times 10^{38}$ 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 from MAXI 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.