SIMBAD references

We explore thermal X-ray iron line emission from the galactic X-ray binary GX 339-4 in the off state, using the models of the advection-dominated accretion flow (ADAF) without or with outflows. The equivalent widths of hydrogen-like and helium-like thermal iron lines are calculated with different model parameters including viscosity parameter α, mass accretion rate at the outer radius of the ADAF {dot}m_out, and outflow strength parameter p. Our calculations show that the equivalent widths of thermal iron lines emitted from the pure ADAF, i.e., the ADAF without outflows, should be very small, assuming a solar metallicity for the accreting gas in the accretion flow. Strong thermal iron lines are expected to be emitted from the ADAF with relatively strong outflows. For a reasonable choice of parameters, the total equivalent width of the He-like and H-like thermal iron lines reaches to ≳500 eV for accreting gas with solar metallicity. The observation of strong thermal X-ray lines from GX 339-4 at the off state may give a clue to the accretion mode of the source and provide evidence for the presence of outflows/winds in the accretion flow around the black hole in GX 339-4. It is found that the values of {dot}m_out and p are degenerate, i.e., the observed X-ray continuum spectrum can be fairly well reproduced with different sets of the parameters {dot}m_out and p. Such degeneracy can be broken when the thermal X-ray line emission data are available. We also compare our results with those in a previous similar work.