Multiwavelength study of the fast rotating supergiant high-mass X-ray binary IGR J16465−4507^⋆

¹ AIM (UMR 7158 CEA/DSM-CNRS-Université Paris Diderot), Irfu/Service d’Astrophysique, Centre de Saclay, 91191 Gif-sur-Yvette Cedex, France
e-mail: chaty@cea.fr
² Institut Universitaire de France, 103 boulevard Saint-Michel, 75005 Paris, France
³ Departamento de Física, Ingeniería de Sistemas y Teoría de la Señal, Escuela Politécnica Superior, Universidad de Alicante, Carretera San Vicente del Raspeig s/n, 03690 San Vicente del Raspeig, Spain
⁴ Santa Cruz Institute for Particle Physics, University of California Santa Cruz, 1156 High St., Santa Cruz, CA 95064, USA
⁵ APC (UMR 7164 CEA/DSM-CNRS-Université Paris Diderot), 10 rue Alice Domon et Léonie Duquet, 75013 Paris, France
⁶ Argelander Institut für Astronomie, Auf dem Hügel 71, 53121 Bonn, Germany
⁷ Instituto de Astrofísica de Canarias, vía Láctea s/n, 38205 La Laguna, Santa Cruz de Tenerife, Spain
⁸ Departamento de Astrofísica, Facultad de Física y Matemáticas, Universidad de La Laguna, Avda. Astrofísico Francisco Sánchez, s/n, 38206 La Laguna, Santa Cruz de Tenerife, Spain

Received: 11 January 2016
Accepted: 4 April 2016

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).