The dust - enshrouded microquasar candidate AX J 1639 . 0 − 4642

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. 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. We have also identified a possible NIR counterpart, compatible with a young OB star, provided the absorption takes place close enough to the compact object. After a careful 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 other two MQs previously proposed to display high-energy γ-ray emission.