Evolution of Hard X-Ray Spectra along the Orbital Phase in Circinus X-1

摘要: Using the data from Proportional Counter Array and High-Energy X-Ray Timing Experiment on board Rossi Explorer satellite, we investigate evolution of 3-200 keV spectrum peculiar low-mass X-ray binary Circinus X-1 along its orbital phase. A power-law hard component, dominating above ~30 as well contributing between 0.9% 3.5% total flux, iron emission line are detected in spectrum. It is found that derived photon index (Γ) component characteristics modulated by phase: hardest tail, lowest energy, largest width at periastron. However, softest highest after apastron. At periastron source evolves a complete track color-color diagram. These behaviors modulation discussed. possible origin also