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Reverberation effect in Quasi Periodic Oscillations in Black Hole Candidates.

Reverberation effect in Quasi Periodic Oscillations in Black Hole Candidates. Nikolai Shaposhnikov 1,2,3. 1 University of Maryland, Astronomy Department 2 Center for Research and Exploration in Space Science & Technology (CRESST) 3 NASA/Goddrd Space Flight Center.

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Reverberation effect in Quasi Periodic Oscillations in Black Hole Candidates.

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  1. Reverberation effect in Quasi Periodic Oscillations in Black Hole Candidates. Nikolai Shaposhnikov1,2,3 1University of Maryland, Astronomy Department 2Center for Research and Exploration in Space Science & Technology (CRESST) 3NASA/Goddrd Space Flight Center RXTE Symposium, GSFC, March 29, 2012

  2. QPO Reverberation In Black Hole Sources QPOs in Black Hole Candidates. • Quasi-periodic Oscillation is almost periodic flux modulation near some frequency. • Low frequency QPOs are seen in low-hard and intermediate states and are strongly correlated with a source spectral characteristics. • QPOs are coupled with the non-thermal part of the spectrum. QPO disappear in soft state. • Usually QPO show two or even three harmonics and sometimes a sub-harmonic. • Many physical models are proposed including (but not limited to) coronal oscillation (Titarchuk&Osherovich), precession (Stella&Vetri), discoseismology (Wagoner&Nowak), Alven waves (Tagger& Pellat)… • No model have described convincingly described all QPO phenomenology RXTE Symposium 2012 N. Shaposhnikov

  3. QPO Reverberation In Black Hole Sources Fourier Phase Analysis XTE J155-564 HIMS XTE J155-564 SIMS GRS 1915+105 SIMS XTE J1550-564; Cui et al. 2000, Remillard et al. 2002; Casella et al. 2004 and many more … RXTE Symposium 2012 N. Shaposhnikov

  4. QPO Reverberation In Black Hole Sources Phase relationshipbetweenQPO harmonics Time shift between Fourier Components RXTE Symposium 2012 N. Shaposhnikov

  5. QPO Reverberation In Black Hole Sources QPO waveform parametrization. where, Misra, R, 2001, Proceedings of a joint workshop held by the Center for Astrophysics (JHU) and the LHEA (NASA/GSFC) A model for the alternating lags in 67 mHz QPO harmonics observed in GRS 1915+105 is presented where variations in the photon spectrum are caused by oscillations in two parameters that characterize the spectrum. It is further assumed that variations in one of the parameters is linearly driven by variations in the other after a time delay td. RXTE Symposium 2012 N. Shaposhnikov

  6. QPO Reverberation In Black Hole Sources Reverberation model. Reverberation (response) Perturbation - QPO frequency - Dumping coefficient - Perturbation amplitude - Reverberation amplitude - Reverberation phase and time delay Note: reverberation amplitude and phase delay are functions of energy. The reverberation parametrization is NOT a pivoting power law. RXTE Symposium 2012 N. Shaposhnikov

  7. QPO Reverberation In Black Hole Sources Reverberation model for Fourier transform data products. Fourier transform: Phase delay: Power Spectrum: RXTE Symposium 2012 N. Shaposhnikov

  8. XTE J1550-564 HIMS XTE J1550-564 SIMS QPO Reverberation In Black Hole Sources QPO reverberation model. Application to data. • νQPO=2.4 Hz • a = 1.3 • b1 = 0.8 • b2 = 0.82 • φ1 = 1.17 • φ1 = 1.35 • λ = 0.56 • νQPO=2.4 Hz • a = 1.17 • b1 = 0.74 • b2 = 0.3 • φ1 = 1.27 • φ1 = 1.15 • λ = 2.1 RXTE Symposium 2012 N. Shaposhnikov

  9. GRS 1915+105 Plato state QPO Reverberation In Black Hole Sources QPO reverberation model. Application to data. • νQPO=3.0 Hz • a = 4.43 • b1 = 1.35 • b2 = 0.8 • φ1 = 2.7 • φ1 = 3.2 • λ = 1.77 RXTE Symposium 2012 N. Shaposhnikov

  10. QPO Reverberation In Black Hole Sources Evolution of QPOpower and phase with energy GRS 1915+105 Reflection From the disk RXTE Symposium 2012 N. Shaposhnikov

  11. Phase relation in QPO On the nature of QPO Noise Oscillations are dumped (described by non-zero width Lorentzians), forced (signified by the presence of a broad-band noise), non-linear (dictated by the nature of the QPO waveform. Such a system has a (weak) resonance at ν1/2,i.e. has to show subharmonic! A property of the phase difference δ between the oscillation and the phase and external force is that it is always negative, i.e. the oscillation “lags behind” the force. Landau&Lifshitz, Mechancs RXTE Symposium 2012 N. Shaposhnikov

  12. Phase relation in QPO QPO reverberation effect highlights Reverberation model fits energy dependent PDS and phase lags, i.e. describes RMS spectra - RMS-Flux relationship (Uttley et al.)! Fits nicely into the truncated disk scenario where an outer disk provides the perturbing force while the Comptonizing inner region serves as an oscillating system RXTE Symposium 2012 N. Shaposhnikov

  13. We have identified a new observational effect, reverberation effect in QPO • Reverberation QPO model consistently describes various aspects of QPO behavior including their PDS appearance, time lags, energy dependence, RMS-flux relationship etc. • The model describes both positive (hard) and negative Fourier phase lags, within a simple physical model. Fourier time lags should not be treated as physical times!Proper model is required... • QPO reverberation (times vs energy) allows probing the inner region of the accretion flow, i.e. to measure its size. • Thanks to RXTE we have great archive of unique data. • RXTE showed the importance of timing. Time is (only?) the extra resolution domain for compact systems. • Future! ASTROSAT, JEMS, LOFT, AXTAR… Phase relation in QPO Conclusions RXTE Symposium 2012 N. Shaposhnikov

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