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Ron Remillard Kavli Institute for Astrophysics and Space Research

XIV Advanced School on Astrophysics Topic III: Observations of the Accretion Disks of Black Holes and Neutron Stars. Ron Remillard Kavli Institute for Astrophysics and Space Research Massachusetts Institute of Technology http://xte.mit.edu/~rr/XIVschool_III.1.ppt.

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Ron Remillard Kavli Institute for Astrophysics and Space Research

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  1. XIV Advanced School on AstrophysicsTopic III: Observations of the Accretion Disks of Black Holes and Neutron Stars Ron Remillard Kavli Institute for Astrophysics and Space Research Massachusetts Institute of Technology http://xte.mit.edu/~rr/XIVschool_III.1.ppt

  2. Topic III: General Outline III.1 Accretion States of Black Hole Binaries (I) • X-ray Astronomy and Identification of Accreting Binaries • Properties of Compact Objects and Accretion Disks • Different X-ray States in Black Hole Binaries • Thermal State: Thermal Radiation from the Accretion Disk III.2 Accretion States of Black Hole Binaries (II) • Observations of the Black Hole Hard State • Observations of the Steep Power Law State • Transients in Quiescence • X-ray Quasi-Periodic Oscillations in Black Hole Binaries III.3 Accretion Disks around Neutron Stars • Timing Properties of Accreting Neutron Stars • Observations of Atoll Type Sources • New Interpretations for Z Type Sources

  3. III.1 Accretion States of Black Hole Binaries (I) • Introduction to X-ray Binary Systems • Context for X-ray Astronomy • Classifications of X-ray Binaries • Black Holes, Neutron Stars, & Accretion Disks • Physical Properties • Measurement Techniques • X-ray States of Black Hole Binaries • Spectral/Timing Evolution of Accreting Black Holes • Illustrations of Black Hole X-ray States • Thermal State: Hot Accretion Disk • Expectations and Definition of the Thermal State • Building the Paradigm for the Thermal State

  4. X-ray Photons • Wien’s Displacement Law (1893)--- 10 Angstroms (wavelength (l) of max. energy flux in I(n)) is very hot ! T = 5 x 107 oK / lmax(Angstroms) Wilhelm Carl Werner Otto Fritz Franz Wien • X-rays: Photons 0.6-12 Angstroms  Energies 20-1 keV • Thermal Equivalent kT = 4 to 80 million oK • Heating mechanisms  non-thermal processes synchrotron radiation (high energy e- in B field) inverse Compton (photon upscattered by high energy e-)

  5. Window for Astrophysics from Space Photon transmission through the Galaxy • X-rays: recover long-distance view at E > 1 keV

  6. X-ray Telescopes in Space XMM-Newton (European Space Agency) Chandra (NASA Great Observatory) MIRAX (small mission planned by Brazil) Rossi X-ray Timing Explorer (NASA)

  7. Brightest X-ray Sources (10 to 10-3 Crab) Milky Way Sourcesprimary X-spectrum Accreting Neutron Stars Atoll- and Z-sources thermal ; non-thermal hard state Accretion-powered Pulsars non-thermal Isolated Pulsars mixed types Accreting Black Holes thermal + non-thermal states Supernova Remnants thermal (shocks) Stellar Coronae thermal (B instability) Accreting White Dwarfs thermal Extragalactic Active Galactic Nuclei non-thermal (hard state) Blazars non-thermal (jets) Clusters of Galaxies thermal (bremsstrahlung) _____________ 1.0 Crab ~ 2.4x10-8 erg cm-2 s-1 at 2-10 keV

  8. Brightest X-ray Sources (10 to 10-3 Crab) Milky Way Sourcesprimary X-spectrum accretion disk Accreting Neutron Stars Atoll- and Z-sources thermal ; non-thermal hard state yes Accretion-powered Pulsars non-thermal Isolated pulsars mixed types Accreting Black Holes thermal + non-thermal states yes Supernova Remnants thermal (shocks) Stellar Coronae thermal (B instability) Accreting White Dwarfs thermal yes Extragalactic Active Galactic Nuclei non-thermal (hard state) yes Blazars non-thermal (jets) yes Clusters of Galaxies thermal (bremsstrahlung) _____________ 1.0 Crab ~ 2.4x10-8 erg cm-2 s-1 at 2-10 keV

  9. Binary Evolution for Accreting Compact Objects • Scenario 1: Roche Lobe overflow • More massive star dies first • Binary separation can shrink • (magnetic braking and/or grav. radiation) • Companion may evolve and grow • Common for Low-Mass (Companion) • X-ray Binaries (LMXB) • Scenario 2: Stellar Wind Accretion • More massive star dies first • Stellar wind captured (with possible inner accretion disk) • Common for High-Mass (Companion) • X-ray Binaries (HMXB)

  10. Properties of Black Holes • mass: Mx • Spin parameter: a* = cJ / GMx2(J = angular momentum ; dimensionless 0 < a* < 1 ; Erot < 0.29 M) • charge: assume Qx = 0 (local plasma prevents charge buildup) • event horizon ! (math. surface of ‘no escape’) (see Shapiro & Teukolsky 1983; Narayan 2004) Can spin be measured? Will quantitative, GR-based astrophysics be successful? Accretion disk observations / accretion theory are the primary tools!

  11. Measuring Masses of Compact Objects Dynamical study: compact objectx and companion starc (for binary period, P, and inclination angle, i ) Kepler’s 3rd Law: 4 p2 (ax + ac)3 = GP2 (Mx + Mc) center of mass: Mxax = Mc ac radial velocity amplitude Kc= 2 pac sin iP-1 “Mass Function”:f(M) = PK3/ 2pG = Mx sin3(i) / (1 + Mc/Mx)2 < Mx Techniques to infer i and estimate Mc/Mx (see references) Mx

  12. Compact Object Mass Neutron Star Limit: 3 Mo (dP/dr)0.5 < c Rhoades & Ruffini 1974 Chitre & Hartle 1976 Kalogera & Baym 1996 Black Holes (BH) Mx = 4-20 Mo Neutron Stars (NS) (X-ray & radio pulsars) Mx ~ 1.4 Mo

  13. Black Holes in the Milky Way 18 BHBs in Milky Way 16 fairly well constrained  (Jerry Orosz) Scaled, tilted, and colored for surface temp. of companion star.

  14. Identifications of X-ray Binaries NS Binary: X-ray Bursts or Coherent X-ray Pulsations NS Candidates:resemble NSBs in spectral & timing properties (limited info.) BH Binary:Mass > 3 Mo from binary analyses ; no NS properties BH Candidate: BHB X-ray properties + no pulsations + no X-ray bursts Dynamical BHBsBH Candidates Milky Way 18 27 LMC 2 0 nearby galaxies 3 (e.g., M33-X7) (? many ULXs) --------------------- ----------------------------- ---------------------------- total 23 27 + ? Transients 17 25 + ?

  15. Accretion Disks and the Inner Disk Boundary Keplerian orbits for accreting m E(r)= U+K = 0.5 U(r) = -0.5 G Mx m r -1 Particle dE/dr = 0.5 G Mx mr -2 = L(r) ~ d (dE/dr) = 0.5 e G Mx mr -2 dt L(r) ~2pr dr sT4 T(r) ~ r -3/4 • Real physical model (and MHD simulations): • transport & conserve angular momentum; outflow?, rad. efficiency (e) • 3-D geometry (disk thickness, hydrostatic eq., radiative transfer) • B-fields and instabilities • GR effects (Innermost Stable Circular Orbit, grav. redshift, beaming)

  16. Accretion onto Compact Objects Compact Object Mo ; <Rkm> GMmR-1 / mc2 Boundary Condition white dwarf 0.4-1.3 ; 6000 10-4 crash on surface neutron star 1.4-2.0 ; ~10 0.2 crash on surface black hole 4-20 ; ~30a ~0.5 event horizon BH accretion disk ~60a ~0.2 innermost stable(a for 10Mo, a* = 0.5) circular orbit (ISCO) Milky Way Today: 108-109 BHs ; ~109 NSs ; > 1010 WDs (Timmes, Woosley & Weaver 1996; Adams and Laughlin 1996)

  17. Inner Disk Boundary for Accretion Disks • Black Holes: Innermost Stable Circular Orbit (ISCO) BH spin a*: 0.0 0.5 0.75 0.9 0.98 1.0 ----------------------------------------------------- ISCO (Rg / GMx/c2): 6.0 4.2 3.2 2.3 1.6 1.0 • Neutron Stars Inner Accretion Disk (? RNS < RISCO ?) NS Surface  Boundary Layer (2nd heat source) NS Spin (can influence bounday layer physics) Magnetic Field Affects (Alfven Radius; control of inner accretion flow ; accretion focus at polar cap  pulsars)

  18. Black Hole X-ray Transient (or ‘X-ray Nova’) GRO J1655-40 First known outbursts: 1994-95; () 1996-97; 2005 Dynamical black hole binary 6.3 (+0.5) Mo Relativistic Jets in 1994 ~Radio-quiet, 1996-97, 2005

  19. Black Hole X-ray Transient GRO J1655-40  Different X-ray States

  20. Illustrating 3 BH States of Active Accretion Energy spectraPower density spectra Statephysical picture steep power law Disk + ??  thermal hard state Energy (keV) Frequency (Hz)

  21. Illustrating 3 BH States of Active Accretion Energy spectraPower density spectra Statephysical picture steep power law Disk + ??  thermal hard state Energy (keV) Frequency (Hz)

  22. Time Series of Accretion States GRO J1655-40 1996-97 outburst Thermal x Hard (jet)g Steep Power Law D Intermediate O

  23. Time Series of Accretion States XTEJ1550-564 Mx = 9.6 + 1.2 Mo Thermal x Hard (jet)g Steep Power Law D Intermediate O

  24. Thermal State of Black Hole Binaries • ThermalState: radiant heat of the inner accretion disk • disk fraction (2-20 keV) in energy spectrum: fdisk > 75% ; • power continuum (integrated 0.1-10 Hz): rms < 0.075 ; • no quasi-periodic oscillations (QPOs): amax < 0.5%

  25. Thermal State Paradigm Theory: Hot gas in thin disk + viscous dissipation Rel. MHD: Plasma + Magneto-Rotational Instability  Thermal radiation ; weakly magnetized disk Disk blackbody shape? Disk blackbody energetics? Kubota & Done 2004; Gierlinski & Done 2004 T(r)ar-p; p ~ 0.7 (Kubota et al 2005) (GR tweak of p=0.75)

  26. Other Measures of Disk Structure Disk Structure Changes in Other States? GX339-4 Relativistic Fe line e.g. Miller et al. 2004; but see Merloni & Fabian 2003

  27. GR Applications for Thermal State Emissivity vs. Radius in the Accretion Disk Shakura & Sunyaev 1973; Makishima et al. 1986; Page & Thorne 1974; Zhang, Cui, & Chen 1997 Gierlinski et al. 2001; Li et al. 2005

  28. GR Applications for Thermal State Relativistic Accretion Disk: Spectral Models • e.g. kerrbb in xspec • Li et al. 2005; Davis et al. 2005 • Integrate over disk and Bn(T) • Correct for GR effects • (grav-z, Doppler, grav-focusing) • Correct for radiative transfer

  29. Thermal state  BH spin Analyses of thermal state observations with new GR-disk models  quantitative measures of a*  Narayan Lecture (tomorrow)

  30. Appendix: Tools for X-ray Data Analysis MethodApplicationComments Images impulsive BJB jets two cases (Chandra) Spectrum Model Continuum accretion disk BH: infer a* if known Mx ; d Model Hard X-rays hot corona / Comptonization two types: (1) jet ; (2) ??? Spectral Lines BH: broad Fe K-a (6.4 keV) corona fluoresces inner disk emission profile  Mx ; a* ‘’ high-ioniz. absorption lines seen in a few BHs variable, magnetized disk? ‘’ redshifted absorption line 1 NS?: surface grav. redshift

  31. Appendix: Tools for X-ray Data Analysis MethodApplicationComments Timing Period Search NS: X-ray Pulsars several types; measure dP/dt and pulse-profiles(E) ‘’ NS or BH binary orbits wind-caused for HMXB some LMXB eclipsers, dippers ‘’ Long-term Periods precessing disks ; ? slow waves in dM/dt ? Quasi-Period Oscillations BH and NS rich in detail low n (0.1-50 Hz) common in some states high n (50-1300 Hz) NS: var. n ; BH steady harmonics very slow (10-6 to 10-2 Hz) some BH: disk instability cycles

  32. Appendix: Tools for X-ray Data Analysis MethodApplicationComments Timing Aperiodic Phenoma ‘’ Type I X-ray Bursts in NS thermonucl. explosions on surface ID as NS ; oscillations  spin ; infer distance ; physical models improving ‘’ Type II X-ray Bursts two NS cases ; cause ?? ‘’ Superbursts (many hours) C detonation in subsurface ? Probe NS interiors ‘’ Giant flares in Magnetars ? crust shifts + B reconnection Progress?: coordinated timing / spectral analyses

  33. References: Reviews “Compact Stellar X-ray Sources”, eds. Lewin & van der Klis (2006) ; 16 chapters; some on ‘astro-ph’ preprint server: http://xxx.lanl.gov/form Overview of Discovery Psaltis astro-ph/0410536 Rapid X-ray Variability van der Klis astro-ph/0410551 X-ray Bursts Strohmayer & Bildsten astro-ph/0301544 Black Hole Binaries McClintock & Remillard astro-ph/0306213 Optical Observations Charles & Coe astro-ph/0308020 Isolated Neutron Stars Kaspi, Roberts, & Harding astro-ph/0402136 Jets Fender astro-ph/0303339 Accretion Theory King astro-ph/0301118 Magnetars Wood & Thompson astro-ph/0406133 Other Reviews: Narayan 2004, “Black Hole Event Horizon”, PThPS, 155, 263 Remillard & McClintock 2006, "X-Ray Properties of Black-Hole Binaries", ARAA, 44, 49 Done. Gierlinski, & Kubota 2007, “Modelling the behaviour of accretion flows in X-ray binaries”, A&A Reviews, 15, 1

  34. References Other references.: Most are in ARAA, 44, 49 or in McClintock & Remillard 2006 (previous slide) Additional References: Adams and Laughlin 1996, ApJ, 468, 576 Done & Gierlinski 2003, MNRAS, 342, 1041 Gierlinski & Done 2004, MNRAS, 347, 885 Kubota & Done 2004, MNRAS, 353, 980 Timmes, Woosley, & Weaver 1996, ApJ, 457, 834 Power Density Spectra and deadtime corrections: Leahy et al. 1983, ApJ, 266, 160 Zhang et al. 1995, ApJ, 449, 930 Dennis Wei undergrad thesis (MIT; 2006): http://xte.mit.edu/~rr/dwei_thesis.pdf

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