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

Abstract

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.

An absorbed view of a new class of INTEGRAL sources

“…So far, only IGR J19140+0951 has a reported orbital period (P orb ≃13.55 days, Corbet et al 2004). 5 If the highly absorbed IGR sources indeed contain (slow) pulsars, their compact object is evidently a neutron star. However, if this interpretation is not correct, a black hole can not be excluded either (this is especially true for those IGR sources with no identified pulsations).…”

Identifications of FourINTEGRALSources in the Galactic Plane viaChandraLocalizations

“…For many of these sources, their X-ray spectra show high column densities with values of N H well in excess of the levels expected due to interstellar material. The most extreme example is IGR J16318À4848, for which N H $ 2 ; 10 24 cm À2 (Matt & Guainazzi 2003;Walter et al 2003), and there are also several other sources with values of N H in the 10 23 -10 24 cm À2 range (e.g., Rodriguez et al 2003;Combi et al 2004;Beckmann et al 2005). Many of the Galactic IGR sources also exhibit X-ray pulsations, indicating the presence of a neutron star.…”

The gamma-ray emitting microquasar LS I +61 303

“…In ejections distant enough from the Be star it could be verified if also disk photons are upscattered by the relativistic electrons and contribute to the gamma-ray emission [21], such a contribution would finally explain why LS I +61 303 is subluminous in the X-ray range (see Table 1, adapted from [22]). …”