Xrays from Quiescent Black Holes: Accretion or Jet Powered

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X-rays from Quiescent Black Holes Accretion or
Jet Powered?

• Wei Cui
• Purdue University

Collaborators Gabor Pszota, Purdue
University Feng Yuan, Shanghai Astronomical
Observatory Hui Zhang, Shanghai
Astronomical Observatory
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Stellar-Mass Black Holes

• 21 dynamically determined BH X-ray binaries
• about 2 dozens more BH candidates
• Only 4 are persistent X-ray sources
• all with OB secondary stars
• Transients constitute the majority
• nearly all with late-type secondary stars

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Outbursts
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Spectral States
XTE J1550-564
Xue, Wu, Cui 2008
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Low-Hard State
Yuan, Cui, Narayn 2005
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Modeling Low-Hard State
Yuan, Cui, Narayn 2005
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Extrapolation to Quiescence
Yuan Cui 2005
The shape of X-ray spectra deviates from a power
law in the quiescent state.
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XMM-Newton Observations

• GRO J1655-40 185 ks, Fx 5.8 x 10-14 erg s-1
  cm-2
• in two segments, separated by about 1 month
• XTE J1550-40 59 ks, Fx 4.9 x 10-14 erg s-1
  cm-2
• but severely contaminated
• V404 Cyg 40 ks, Fx 40 x 10-14 erg s-1 cm-2
• archival observation

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Quiescent X-ray Spectra
Pszota et al. 2008
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Can AFAF Fit?
Pszota et al. 2008
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Conclusions

• The observed X-ray spectra of GRO J1655-60 and
  V404 Cyg in the quiescent state deviate strongly
  from the expectation of ADAF models.
• The power-law shape of the X-ray spectra can be
  explained by a dominant jet contribution.
• The case of XTE J1550-564 is still ambiguous, as
  limited by the statistics of the data.

Pszota et al. 2008, MNRAS
12
Another Test
Yuan Cui 2005