TIMING THE ACCRETION FLOW AROUND ACCRETING MILLISECOND PULSARS

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TIMING THE ACCRETION FLOW AROUND ACCRETING
MILLISECOND PULSARS

• Manuel Linares
• Michiel van der Klis, Rudy Wijnands, et al.

Linares, van der Klis, Altamirano Markwardt,
2005, ApJ. Linares, van der Klis Wijnands,
2007, ApJ. Linares, Wijnands, van der Klis,
Krimm, Markwardt Chakrabarty, 2008, ApJ.
Accreting millisecond pulsars. Amsterdam,10 years
later.
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A low-mass X-ray binary (LMXB)
Hynes
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Aperiodic timing analysis RXTE-PCA
Time domain
? Frequency domain e.g.
Exponentially damped sinusoid ?
Lorentzian
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XTE J1807-294

• 4U 1728-34

XTE J1807-294
AVERAGE SEPARATION 205-6 Hz
PULSE 191 Hz
? Michiels talk
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XTE J1807-294
1.59 shift in lower and upper kHz QPOs

• 4U 1728-34

XTE J1807-294
XTE J1807-294
4U 1728- 34
? Michiels talk
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IGR J002915934 Linares et al 2007
0.05 Hz
0.12 Hz
XTE J1807-294 Linares et al 2005
10.2 Hz
SWIFT J1756.9-2508 Linares et al 2008
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BREAK FREQUENCY vs. MASS

• Some frequencies scale as 1/M
• ?Kepl R-3/2 M1/2 r-3/2 1/M (rR/Rg)
• ?isco 1/M
• This has been used to infer SMBH mass in AGN
• (scaling from Cyg X-1 e.g. Uttley et al 2002)
• HOWEVER
• What timescale are we dealing with?
• (Dynamical, shot lifetime, viscous? Priedhorsky
  e.a.1979, Lyubarskii 1997)
• Measurement identification of a break frequency
  in AGN is not trivial
• (recent efforts in Uttley McHardy 2005)
• Weve just seen a NS-LMXB with a break frequency
  lower than a BH-LMXB!
• Break frequency moves in LMXBs

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SWIFT J1756.9-2508

• Break frequency follows light curve decay. Are
  break frequency and accretion rate correlated?

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4U 1608-52 (AMPs are also atolls)
Hasinger van der Klis 1989
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4U 1608-52 (AMPs are also atolls)

• Simple L - ?break relation does not work! (Done
  Gierlinski 2005)
• Neither does Mdot - ?break with the usual
  assumption.
• Other attempts spectral hardness/photon index
  (Shaposhnikov Titarchuk 2007)

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Conclusions

• AMPs have shed light on kilohertz QPOs SAX
  J1808, XTE J1807 (although the whole sample of
  kilohertz QPO sources has to be considered)
• One of them has shown the strongest noise in any
  neutron star LMXB IGR J00291
• IGR J00291 also challenges inverse mass scaling
  of frequencies break frequency lower than many
  BH systems!
• Drifts in break frequency are not only due to
  changes in mass accretion rate (in X-ray
  luminosity)