Spectral State Transitions of the Ultraluminous X-Ray Sources X-1 and X-2 in NGC 1313

  title={Spectral State Transitions of the Ultraluminous X-Ray Sources X-1 and X-2 in NGC 1313},
  author={Hua Feng and Philip Kaaret},
  journal={The Astrophysical Journal},
X-ray spectral state transitions are a key signature of black hole X-ray binaries and follow a well-defined pattern. We examined 12 XMM-Newton observations of the nearby spiral galaxy NGC 1313, which harbors two compact ultraluminous X-ray sources (ULXs), X-1 and X-2, in order to determine if the state transitions in ULXs follow the same pattern. For both sources, the spectra were adequately fitted by an absorbed power law with the addition of a low-temperature (kT = 0.1-0.3 keV) disk blackbody… Expand

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