The dust-enshrouded microquasar candidate AX J1639.0-4642 = IGR J16393-4643

¹ Departamento de Física, Escuela Politécnica Superior, Univ. de Jaén, Virgen de la Cabeza 2, 23071 Jaén, Spain e-mail: jcombi@ujaen.es
² Service d'Astrophysique, CEA Saclay, Bât. 709, L'Orme des Merisiers, 91191 Gif-sur-Yvette Cedex, France e-mail: [mribo;mirabel]@discovery.saclay.cea.fr
³ Instituto Argentino de Radioastronomía, C.C.5, (1894) Villa Elisa, Buenos Aires, Argentina
⁴ Instituto de Astronomía y Física del Espacio, CONICET, C.C.67, Suc. 28, 1428 Buenos Aires, Argentina
⁵ Santa Cruz Institute for Particle Physics, University of California, 1156 High Street, Santa Cruz, CA 95064, USA e-mail: sugizaki@scipp.ucsc.edu

Received: 31 January 2004
Accepted: 17 April 2004

Abstract

We present a multiwavelength study of the field containing the unidentified X-ray source AX J1639.0-4642, discovered with the ASCA observatory and recently detected with the IBIS telescope, onboard the INTEGRAL satellite, dubbed IGR J16393-4643. The huge hydrogen column density towards the source, the hard spectral index in the 0.7–10 keV band and its flux variability suggest that the source is a High Mass X-ray Binary (HMXB) enshrouded by dust. Our search reveals the presence of a non-thermal radio counterpart within the X-ray error box. After a study of the broadband emission from X-rays to the radio domain, we propose that AX J1639.0-4642 is a dust-enshrouded Microquasar (MQ) candidate. In addition, the X-ray source is well within the 95% location contour of the unidentified γ-ray source 3EG J1639-4702. The main properties of AX J1639.0-4642/3EG J1639-4702 are consistent with those of two other MQs previously proposed to display high-energy γ-ray emission.