Properties of 2017–18 ‘failed’ outburst of GX 339-4

Abstract

The Galactic transient black hole candidate GX 339-4 is a very interesting object to study as it showed both complete and failed types of outbursts. We studied both spectral and temporal properties of the 2017–18 outburst of the source using archival data of NICER, AstroSat, MAXI and NuSTAR satellite instruments. This 2017–18 outburst is found to be failed in nature, as during the entire period of the outburst, the source was only in the hard spectral state. Source spectra were highly dominated with the non-thermal fluxes. When we tried to fit spectra with phenomenological models, most of the spectra were fitted with only the powerlaw model, and only six spectra required disk black body plus powerlaw models. While fitting spectra with the physical two-component advective flow (TCAF) model, we observed that the flow was highly dominated by the sub-Keplerian halo rate. The presence of stronger shock at a larger radius from the black hole was also observed during the rising and declining phases of the outburst. A prominent signature of 0.31 Hz QPO is observed with possibly three harmonics.