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INPE%20Advanced%20Course%20on%20Compact%20Objects%20Course%20IV:%20Accretion%20Processes%20in%20Neutron%20Stars%20

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INPE Advanced Course on Compact Objects Course IV: Accretion Processes in Neutron Stars & Black Holes Ron Remillard Kavli Center for Astrophysics and Space Research – PowerPoint PPT presentation

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Title: INPE%20Advanced%20Course%20on%20Compact%20Objects%20Course%20IV:%20Accretion%20Processes%20in%20Neutron%20Stars%20


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
  • Wiens Displacement Law (1893)
  • (wavelength (l) of max. energy flux in I(n))
    --- 2 keV is 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 gt 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?
  • lt 8 Mo white dwarf degenerate
    isolated binaries (0.4-1.3 Mo
    Earth-size) gas pressure cataclysmic
    variables
  • 8-25 Mo neutron star strong
    nuclear force radio pulsars hot-
  • (1.4-2.0 Mo R10 km)
    isolated X-ray pulsars X-ray
    bursters
  • gt 25 Mo black hole no
    classical forces accreting binaries
  • (3-16 Mo event horizon) quantum gravity?
    (X-ray sources)
  • Milky Way Today 108-109 BHs 109 NSs gt
    1010 WDs
  • (Timmes, Woosley Weaver 1996 Adams and
    Laughlin 1996)

8
Collapsed Remnants of Old Stars
  • Compact Object ltMogt ltRcmgt 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 )
  • Keplers 3rd Law 4 p2 (ax ac)3 GP2 (Mx
    Mc)
  • center of mass Mx ax Mc ac
  • radial velocity amplitude Kc 2 p ac sin i
    P-1
  • Mass Function f(M) P K3 / 2pG Mx
    sin3(i) / (1 Mc/Mx)2 lt Mx
  • Dynamical Black Hole Mx gt 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 lt 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 BHBs BH 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
  • Subtype Typical Characteristics Number
    Transients
  • 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 Pulsars (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 gt 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 (lt108 to gt1015 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) UK 0.5
U(r) -0.5 G Mx m r -1 Particle dE/dr 0.5 G
Mx m r -2

dL(r) d
(dE/dr) 0.5 e G Mx m r -2 dt dL(r) 2p
r 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 ltlt R
  • high radiative efficiency (local L release)
  • Makishima et al. 1986 apply to obs.
  • T(r) r -3/4 L 4p Rin2 s 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 lt 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
  • Method Application Comments
  • 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
  • Method Application Comments
  • 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
  • Method Application Comments
  • 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?
  • Thermal State
  • 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)
  • Topic Black Hole Neutron Star Model
  • 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 gt 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/fo
    rm
  • 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,
    AA Reviews, in press, astro-ph/07080148
  • X-ray Binary Catalogs
  • (HMXB) Liu, van Paradijs, van den Heuvel
    2006, AA, 455, 1165
  • (LMXB) Liu, van Paradijs, van den Heuvel
    2007, AA, 469, 807
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