Evolution of MAXI J1631-479 during the January 2019 outburst observed by INTEGRAL/IBIS

M. Fiocchi, F. Onori, A. Bazzano, A. J. Bird, A. Bodaghee, P. A. Charles, V. A. Lepingwell, A. Malizia, N. Masetti, L. Natalucci, P. Ubertini

Research output: Contribution to journalReview articlepeer-review

6 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)3657-3661
Number of pages5
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
Publication statusPublished - 1 Mar 2020


  • Binaries
  • Black holes
  • Individual:MAXI J1631-479
  • Neutron
  • Non-thermal
  • Radiationmechanisms
  • Stars
  • X-rays

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


Dive into the research topics of 'Evolution of MAXI J1631-479 during the January 2019 outburst observed by INTEGRAL/IBIS'. Together they form a unique fingerprint.

Cite this