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Ron Remillard Kavli Center for Astrophysics and Space Research

INPE Advanced Course on Compact Objects Course IV: Accretion Processes in Neutron Stars & Black Holes. Ron Remillard Kavli Center for Astrophysics and Space Research Massachusetts Institute of Technology http://xte.mit.edu/~rr/inpe_IV.5.ppt.

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Ron Remillard Kavli Center for Astrophysics and Space Research

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  1. INPE Advanced Course on Compact ObjectsCourse IV: Accretion Processes in Neutron Stars & Black Holes Ron Remillard Kavli Center for Astrophysics and Space Research Massachusetts Institute of Technology http://xte.mit.edu/~rr/inpe_IV.5.ppt

  2. IV.5 Variability in X-ray Binary Systems • msec X-ray Pulsars • Sources and Significance • Timing and Spectral Properties • Aperiodic Variability in Accreting Neutron Stars • Type I X-ray Bursts • Type II X-ray Bursts • Superbursts • kHz QPOs • Aperiodic Variability in Black Holes • Impulsive Relativistic Jets • Weaker Types of Impulsive Jets • Wild Instability Cycles in GRS1915+105

  3. Msec X-ray Pulsars SourceSpin (Hz)Orbit (hr)Bursts (Hz) IGR J00291+5934 599 2.45 XTE J0929-314 185 0.73 XTE J1751-305 435 0.70 XTE J1807-294 191 0.58 SAX J1808.4-3658 401 2.00 bursts (401) XTE J1814-338 314 4.27 bursts (314); not wd? HETE J1900.1-2455 377 1.39 bursts Swift J1756.9-2508 182 0.90 • Characteristics: • Extremely compact binaries; wd companion (Rc~0.05 Ro; Mc~0.02 Mo) • Tip of reservoir of accretion-spun-up pulsars visible in X-rays • Key to spin-ID of burst oscillations • Key to inventory of spin distributions • Key toward a model for kHz QPOs

  4. Msec X-ray Pulsars XTE J0929-314: typical, faint transient peak ~ 30 mCrab (1.5-12 keV) outburst duration ~65 days HETE J1900.1-2455: transient persists for 2+ years; brief turnoff ; early end of msec pulsations (Aug. 19, 2005)

  5. Energy Spectra & Power Spectra of msec Pulsars • msec X-ray pulsars resemble • Atoll sources in hard state. • So why don’t atolls pulse • (burst oscillations  • similar spin frequencies) • B ranges different? • accretion plasma buries B? • HETEJ1900 may inform us!

  6. Type I X-ray Bursts Number of bursters ~80 Science Applications: • Neutron-star finder • Burst oscillations ( spin) • Radius-expansion bursts ( distance estimate) • Redshifted abs. lines? (Cottam et al, 2003: 1? Case) • Test burst models • Trace dM/dt at NS surface? • Topic for BH event horizon test (lack of bursts in BH)

  7. Type I X-ray Bursts Burst Oscillations e.g., Strohmayer & Markwardt 1999 14 sources of BOs max n = nspin range: 45, 270-619 Hz some frequency profiles are shorter or spotted (on/off) amplitudes increase with energy (Muno et al. 2003)

  8. Type I X-ray Bursts Burst Oscillations multiple nmax measures From the same source give consistent results Muno et al. 2002

  9. Msec X-ray Pulsars and Burst Oscillations • Spin Distribution • Neutron Star Speed limit ~730 Hz • (burst oscillations, radio pulsars, • X-pulsars; Chakrabarty et al. 2003) • Why is limit < breakup freq. • magnetic-accretion spin equilibrium? • Gravitational waves? • (Wagoner 1984; Bildsten 1998) Frequency (Hz)

  10. Type I X-ray Bursts Radius Expansion Bursts e.g., Z-transient XTE J1701-462 Isolate burst spectrum(t) Fit spectra to blackbody (R,t) See R expansion + dip in T evolution  Eddinton Lx  distance estimate (assume Mx, layer composition)  Look for consistent results

  11. Rudimentary Elements of Bursts Models Paradigm: thermonuclear explosion of H, He from accumulated, accreted matter on NS surface • Use Lx as a scale for dM/dt • Assume (vary) MNS and RNS • Assume (vary) composition • Calculate (vary) T of subsurface layer (NS cooling model) • Compute hydrostatic equilibrium • Monitor (r, T) for detonation conditions Many complexities, e.g. differential rotation and turbulent mixing in surface layer (Prio & Bildsten 2007)

  12. Bursts Models Status of burst models (see Strohmayer & Bildsten 2006  many bursters on fast and slow side of burst rate expectations Burst Oscillation Models spot evolution ray tracing for osc. amplitude(t)) Spitkovsky et al 2002, ApJ, 566, 1018 Type I bursts: huge science comeback; 1990s poster-child for “old and boring”

  13. Type II X-ray Bursts Number of sources 2 ; events are NOT thermal 4U1730-33 (rapid burster + type I) ; GRO J1744-28 (bursting pulsar) Linear DE vs. Dt  accretion instability Cause unknown (magnetic?; high-rate ADAF?) Rapid Burster; Inoue 2004, Adv. Sp. Res., 34, 2550 Count rate 0 300 600 Time (s)

  14. SuperBursts in Accreting Neutron Stars Number of sources 8 duration: few to 10 hr triggered by a type I burst recurrence rate: year(s) can excite transient pulsar at spin rate (1636-53) model: C detonation in accretion/burst residue in subsurface layers

  15. kHz QPOs • Properties • move in frequency (300-1200 Hz) • often twin, sometime solo • separation of twins varies slowly Number of sources 26 atolls 16 Z-type 8 msec pulsars 2

  16. kHz QPOs QPO Scales van der Klis 2006 Plot everything vs. upper kHz QPO interpretations controversial Upper kHz QPO

  17. kHz QPOs • Current kHz QPO Models • Beat frequency model (Miller & Lamb) • twin peaks: Keplerian vs. NS surface footprint with RNS < RISCO • twin peak separation interpreted as nspin • However, twin peak separation is nspin or 0.5 nspin • Disk Resonance (Abramowicz & Kluzniak) • TypIcial twin peaks are 600, 900 Hz  3:2 ratio • Resonance model for NS disks

  18. Impulsive, Relativistic Jets in BH Binaries GRS1915+105 jets v > 0.9 c (Mirabel & Rodriguez 1994; Fender et al. 1999) Also GRO J1655-40, Cyg X-3, XTE J1550-564 (see Fender 2006) Special relativity demo; nut beware of assumption of bipolar symmetry Ejection moment not observed in X-rays

  19. Black Holes in the Milky Way Relativistic jets imaged in radio and also in X-rays (Chandra). (Hannikainen et al. 2001; Corbel et al. 2002). Baryonic content of MQ jets still uncertain,except for SS433

  20. Impulsive, Relativistic Jets in BH Binaries • Small-scale impulsive jets • B-cycles of GRS1915+105 (Eikenberry et al. 1998; Fender + Pooley 1998) • strong evidence for disk:jet connection • other LC types (Eikenberry et al. 2007; Rodriguez et al. 2007)

  21. More Complications: Fast X-ray Novae SAX J1819.3-2525 (V4641 Sgr) black hole binary + relativistic radio jets ‘Fast X-ray Nova’ 20 min light curve, Sept 15, 1999 (RXTE)

  22. RXTE Observations of GRS1915+105 1996 – 2006: 1351 obs. (public data; 4.77 Ms)  785 data intervals (4.43 Ms) Quasi-steady 428 (rms < 16%; 1 s bins; 307 hard; 121 soft) Variable Light Curves 357 (rms > 16%)

  23. Light Curve Types: SteadyVariable c hard-steady 304 23 (c-var ) fsoft-steady 64 0 d soft-rolling 36 20 gsoft+dips 21 10 a fast flare sequence + long min. 3 20 b hard dip + trigger + soft spike 0 33 k square waves 0 20 l steady-flicker-dip sequence 0 5 m flicker  steady switching 0 16 n flare-dip sequence + long min. 0 42 r heartbeats (50 s) 0 89 q dropouts to soft and variable 0 44 ….new or inter- combinations 0 35 _______ _______ 428 357

  24. Steady Conditions: Color-Color Diagrams

  25. Steady Conditions & Radio Flux GRS1915+105: coded for radio flux (Ryle telescope, 15 GHz): (x S < 5 mJy; t 5 < S < 25; g 25 < S < 75; gS > 75 mJy ;

  26. BHB Color-Intensity Diagrams GRS1915+105/steady H1743-322 GX339-4

  27. Fast QPOs in GRS1915+105 QPO Frequencies: 41, 67, 113, 165 Hz 67 Hz: 28 (of 785) QPO detections (s > 4): Sample: 67.37 Hz <Q> = 30.2 LC TypeDetect (total)FrequencyQ (freq./FWHM) f 2 (64) 66.23 (0.34) 16 d 8 (56) 65.85 (0.24) 14 g 13 (31) 66.72 (0.21) 11 m 4 (16) 66.92 (0.70) 24 k 1 (20) 68.60 (0.93) 20  67 Hz in “agitated soft state” or thermal:SPL intermediate

  28. QPO near 67 Hz in type-averaged PDS f [64]d [56] g [31]

  29. QPOs in Variable States (avg. PDS; 2-40 kev) n[42] r[89]q[44]

  30. GRS1915+105 Light Curves: q Type bright-hardzone contains a high-frequency QPO

  31. GRS1915+105 : theta-blue Power Density Spectra, blue region QPO (9 s) at 165 +- 3 Hz; harmonic (330 Hz; 3.7 s) Q = 5, ampl = 2% (13-30 keV) Colors resemble steep power-law state

  32. GRS1915+105 Light Curves: u Type Long exposures, July 16-18, 2001. bright-hard zone: 113 Hz QPO at 6-40 keV

  33. High Frequency QPOs from GRS1915+105 Type q : bright-hard zone; 15-40 keV DataFrequencyQ (freq./FWHM) 1997 Sept. 5-29 Remillard et al. 2002 165 (3) 5 1997 June - Oct. Belloni et al. 2006 166 (7) 2 All Type q [44] (all HID zones) 165 (3) 4.7 (0.5) Type n : bright-hard zone; 6-40 keV DataFrequencyQ (freq./FWHM) 2001 July 16-18 Remillard et al. 2004 113 (5) 2 All Type n [42] (all HID zones) 112 (4) 2.2 (0.4)

  34. GRS1915+105 Light Curves: r Type Profile variations within the r group. MIT undergraduate thesis: J. Z. Gazak

  35. GRS1915+105 Light Curves: r Type Recurrence time and flare fractions for the r group. MIT undergraduate thesis: J. Z. Gazak

  36. GRS1915+105 Light Curves: r Type Cycle zones for the r group. MIT undergraduate thesis: J. Z. Gazak

  37. GRS1915+105 Light Curves: r Type [82] keV: 2-40 6-40 15-40 67 Hz in zone1 151 (4) Hz QPO in zone 3 7 s; Q = 3.2 (8 +/- 3 % below 165 Hz)

  38. QPOs in Variable States (avg. PDS; 2-40 kev) n[42] r[89]q[44] 6-40 keV 6-40 keV 15-40 keV

  39. MIRAX Support of Astrophysics PropertiesPhysical ModelsMIRAX Observations Black Holes: mass Binary dynamics locate transients; optical teams spin GR disk spectra thermal state measures & alerts GR resonance (high-n QPOs) SPL state transitions and alerts event horizon Type I burst models deep limits for burst function jets Blandford-Znajek obs. moment of ejection; hard GR MHD? Vertical B? state transitions; radio teams accretion structures GR MHD (Prad regime) measure SPL high-Lx flares

  40. MIRAX Support of Astrophysics PropertiesPhysical ModelsMIRAX Observations Neutron Stars: mass Binary dynamics locate NS transients radius kHz QPO models? bursts; atoll specra? spin Binary evolution theory locate msxp transients burst osc.; superburst osc. magnetic field Mag. evol. models? pulsar cyclotron lines SGR bursts; AXP bursts internal structure NS structure models SGR oscillations & crust Burst Models? Burst and superburst archive jets MHD? hard state; transit.; radio team

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