Multiwavelength study of the fast rotating supergiant high-mass X-ray binary IGR J16465-4507
Goldoni, P.; Chaty, S.; Simón-Díaz, S.; Castro, N.; Coleiro, A.; Negueruela, I.; LeReun, A.; Zurita Heras, J. A.; Goldwurm, A.
France, Spain, United States, Germany
Abstract
Context. Since its launch, the X-ray and γ-ray observatory INTEGRAL satellite has revealed a new class of high-mass X-ray binaries (HMXB) displaying fast flares and hosting supergiant companion stars. Optical and infrared (OIR) observations in a multi-wavelength context are essential to understand the nature and evolution of these newly discovered celestial objects.
Aims: The goal of this multiwavelength study (from ultraviolet to infrared) is to characterise the properties of IGR J16465-4507, to confirm its HMXB nature and that it hosts a supergiant star.
Methods: We analysed all OIR, photometric and spectroscopic observations taken on this source, carried out at ESO facilities.
Results: Using spectroscopic data, we constrained the spectral type of the companion star between B0.5 and B1 Ib, settling the debate on the true nature of this source. We measured a high rotation velocity of v = 320 ± 8km s-1 from fitting absorption and emission lines in a stellar spectral model. We then built a spectral energy distribution from photometric observations to evaluate the origin of the different components radiating at each energy range.
Conclusions: We finally show that, having accurately determined the spectral type of the early-B supergiant in IGR J16465-4507, we firmly support its classification as an intermediate supergiant fast X-ray transient (SFXT).