Detection of a Relativistic Outflow from the Galactic Microquasar GRS 1758-258 in the Hard State

Outflows in the form of collimated jets and wider angle winds are observed ubiquitously from accreting systems. Herein, we present the results of a Suzaku observation of the persistent Galactic microquasar GRS 1758-258 at a luminosity of ∼1% L_{Edd}. Spectral analysis reveals the presence of an absorption feature at an energy of ∼7.5 keV, consistent with the presence of a relativistic outflow (v ∼0.1c). Photo-ionization modeling with XSTAR finds this wind to be highly ionized consistent with absorption by Fe XXVI at a distance of ∼2700 R_g from the black hole. This is the highest velocity wind detected from a stellar mass black hole accretion flow to date, and represents the first detection of a photo-ionized outflow in the hard spectral state, demonstrating the persistent of the wind outflow mechanism down to luminosities of at least 1% L_{Edd}.