1 / 31

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.1.ppt. Course IV Outline.

tallis
Download Presentation

Ron Remillard Kavli Center for Astrophysics and Space Research

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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.1.ppt

  2. Course IV Outline 1. Basic Elements of X-ray Binary Systems 2. Different States of Black-Hole Binaries 3. Weakly Magnetized Neutron-Star Binaries (Atolls and Z sources) 4. Periodic Variability: Orbits and Pulsars 5. Aperiodic Variability: Bursts, Flares & Instability Cycles

  3. IV.1 Basic Elements of X-ray Binary Systems • Introduction • X-ray Astronomy: window to hot and violent universe • Endpoints of Stellar Evolution • Science Goals for Observations of X-ray Binaries • Properties of Neutron Stars and Black Holes • Physical Properties • Mass Determinations • Surveys of Different Types of Compact Objects • Fundamentals of Accretion Physics • The Accretion Disk • Relativistic Disk Models for Black Holes • Non-thermal Radiation Processes • Questions for General Relativity

  4. X-ray Photons Wien’s Displacement Law (1893) (wavelength (l) of max. energy flux in I(n)) --- 2 keVis 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 upscatter 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 Chandra (NASA Great Observatory) • Mirrors (grazing incidence) + gratings? • vs. Collimators (metal baffles) + • Coded Masks (slit plate + shadows) • Spectrometers: Semiconductors (Si); • gas (Xe); CdZnTe pixels for hard-X Rossi X-ray Timing Explorer (NASA) XMM-Newton (European Space Agency

  7. Collapsed Remnants of Old Stars Initial Star Compact Object Support? Observed? < 8 Mowhite dwarf degenerate isolated ; binaries; (0.4-1.3 Mo ; Earth-size) gas pressure cataclysmic variables 8-25 Moneutron star strong nuclear force radio pulsars ; hot- (1.4-2.0 Mo ; R~10 km) isolated; X-ray pulsars; X-ray bursters > 25 Moblack hole no classical forces accreting binaries (3-16 Mo ; event horizon) quantum gravity? (X-ray sources) Milky Way Today: 108-109 BHs ; ~109 NSs ; > 1010 WDs (Timmes, Woosley & Weaver 1996; Adams and Laughlin 1996)

  8. Collapsed Remnants of Old Stars Compact Object <Mo> ; <Rcm> GMmR-1 / mc2 Boundary white dwarf 0.6 ; 6x108 10-4 crash neutron star 1.4 ; 106 0.2 crash black hole 10 ; 3x106 0.5 event horizon

  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. 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 Dynamical Black Hole: Mx > 3 Mo(maximum for a neutron star) BH Candidates: no pulsations + no X-ray bursts + properties of BHBs

  11. 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 = 3-18 Mo Neutron Stars (NS) (X-ray & radio pulsars) Mx ~ 1.4 Mo

  12. Transients with Low-Mass Companions: Best Mx Optical images of A0620-00; BH at 0.9 kpc quiescence outburst 1975 P K3 / 2pG = Mx sin3(i) / (1 + Mc/Mx)2

  13. Optical Study of BH Binary in Quiescence A0620-00 (X-ray Nova Mon 1975) f(M) = 2.72 +/- 0.06 Mo P = 0.323014(1) days K4V companion i ~ 60o Mx = 7 +/- 3 Mo

  14. Optical Study of BHB in Quiescence Optical Photometry of Gravity-distorted K4 star Model( i, fstar , Mc/Mx , Tc, klimb, kgrav) [residual disk; star spots] Other techniques: • Rotational broadening of absorption lines • Doppler curve of emission lines (residual disk) …… worse problems

  15. Inventory of Black Hole Binaries BH Binary:Mass from binary analyses BH Candidate: BHB X-ray properties + no pulsations + no X-ray bursts Dynamical BHBsBH Candidates Milky Way 18 25 LMC 2 0 local group 1 (M33) (? many ULXs) --------------------- --------------------- --------------------- total 21 25 + ? Transients 17 23 + ?

  16. 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.

  17. Inventory of Neutron-Star X-ray Sources SubtypeTypical CharacteristicsNumberTransients Atoll Sources Low-B; LMXBs; X-ray bursts; like BHBs ~100 ~60 Msec X-ray Pulsars 182-599 Hz ; atoll-like X-spectra 8 8 Z-sources high- Lx LMXBs; unique spectral/timing var. 9 1 HMXB or Pulsars hard spectrum + cutoff ; most are X-pulsars ~90 ~50 Magnetars Soft Gama Repeaters (4 + 1 cand.) 14 7 Anomalous X-ray Pul;sars (8 + 1 cand.) Other Isolated Pulsars young SNRs; X-detect radio pulsars 70? 0? ---------- --------- Total 291 126 Cataloged radio pulsars number approaching 2000?

  18. X-ray Transients in the Milky Way • RXTE ASM: • 47 Persistent Sources> 20 mCrab (1.5 ASM c/s) • 80 Galactic Transients • (1996-2007; some recurrent) • Transients: timeline of science opportunities.

  19. Science Goals for Observing X-ray Binaries • Locate stellar black holes and neutron stars100% of BHs from X-ray sources ; special applications for X-selected NSs • Measure Physical Properties of Compact Objects Mass (Mx) Spin NS: pulsations BH: infer a* = cJ / GMx2 BH event horizon compare NS accretion (hard surface) vs. BH (none?) NS surface B field (<108 to >1015 G) NS Interior (Eq. of state; burst models ; oscillation modes) • Understand Accretion Physics origin of different X-ray states ; accretion disk and Rin ; transient jets ; hard X-rays (hot Comptonizing corona) ; quasi-periodic oscillations primary variables: Mx , dM/dt , spin; other variables: i, qspin, surface B (NS), global B, plasma b ?

  20. Accretion Disks and the Inner Disk Boundary Keplerian Orbits for sample 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 = dL(r) ~ d (dE/dr) = 0.5 e G Mx mr -2 dt dL(r) ~2pr dr sT4 T(r) ~ r -3/4 • Real physical model: • conserve angular momentum (viscosity); 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)

  21. Toward a Complete Model of Accretion Disks • Shakura & Sunyaev a-disk (1973) • viscosity scales with total pressure • shear stress: trf = a P (P = Pgas + Prad) • thin disk: h << R • high radiative efficiency (local L release) • Makishima et al. 1986: apply to obs. • T(r) ~ r -3/4 ; L = 4p Rin2s T4 problem : no independent measure of mass accretion rate • MRI: Magneto-Rotational Instability (Balbus &Hawley 1991) • MHD simulations: plasma eddies with local B, are sheared in a rotating disk; • this process transports angular momentum outward. • Continued MHD accretion simulations in General Relativity • (e.g. Hawley & Balbus 2002; DeVilliers, Hawley, & Krolik 2003; McKinney & Gammie 2004) • no dissipation (radiation) included in GR MHD simulations, thus far

  22. 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 Surface (and ? RNS < RISCO ?)  Boundary Layer (2nd heat source) Magnetic Field Affects (Alfven Radius; control of inner accretion flow ; accretion focus at polar cap  pulsars)

  23. 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

  24. 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

  25. 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

  26. 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

  27. 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

  28. Defining X-ray States in BHB? • ThermalState: • inner accretion disk X-ray states  Lecture IV.2

  29. Searches for the Event Horizon Game: model infall to hard surface (NS) vs. none (BH) TopicBlack HoleNeutron StarModel Quiescent X-ray State Measure Lx (erg s-1) 1031 few 1032 advection Thermonuclear Bursts Measure rate (at 0.1 LEdd) none 5x10-5 burst model Thermal X-ray State X-ray Spectrum max. fdisk > 90% 80% boundary layer (Narayan 2004 ; Narayan & Heyl 2002; Remillard et al. 2006; Done & Gierlinski 2003)

  30. 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 Fast Transients, Flashes Heise & in ‘t Zand --- 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

  31. References: Reviews Other Reviews: 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, in press, astro-ph/07080148 X-ray Binary Catalogs: (HMXB) Liu, van Paradijs, & van den Heuvel 2006, A&A, 455, 1165 (LMXB) Liu, van Paradijs, & van den Heuvel 2007, A&A, 469, 807

More Related