The Astrophysics of Stellar Mass Compact Objects
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Observational Properties•
Formation of Stellar Compact Objects•
Compact Objects as Cosmic Laboratories•
Future WorkGALACTIC CENTER IN X-RAYS
Wang et al
Main Categories of Compact Binary Systems
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Stellar Binary X-ray Sources (Black Holes/Neutron Stars with a Companion)
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Cataclysmic Variables (White Dwarf with a Companion)•
Binary Radio Pulsars (Neutron Star/Neutron Star or Neutron Star/White Dwarf Star)HMXB LMXB
X-ray Spectra Hard (>10 keV) Soft (<10 keV) Accreting Star High B field NS
or BH Low B field NS or BH
Accretion
Process Wind Roche lobe
overflow Companion Star High Mass Low Mass
MAIN CLASSES OF X-RAY BINARY SOURCES
Binary Evolution - Roche Geometry
Examples of Typical Binary X-ray Sources
BW Cir GX 339-4
J1859+226 J1650-500
CYG X-1 LMC X-1 LMC X-3 J1118+480 J0422+320 GRS1009-45 A0620-00 GS2000+25 GS1124-684 H1705-25 4U1543-47 J1550-564 J1655-40 J1819-254 V404 CYG GRS1915+105
Casares
GM/Rc 2
Star Radius (km)
Sun 700,000 0.000002
White Dwarf 10,000 0.0002
Neutron Star 10 0.15
Black Hole >3 0.1 - 0.4
ENERGY EFFICIENCIES
Regular NS
Electron capture supernova NS White dwarf
Black hole
Tentative limit
5 7.5 10 12.5 15 17.5 20 22.5
0 1 2 3 4 5
Initial star mass !M!"
Compactobjectmass!M !"
Formation of Compact Objects
Counter example: Westerlund 1
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Young stellar cluster ~ 3-5 Myr with a turnoff mass ~ 35 solar masses•
Existence of a slowly rotating neutron star:CXO J164710.2-455216 (10.6 s) radiating at a luminosity of ~ solar luminosity in X-rays
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Very high observed fraction of binaries (~70%) amongst the high mass populationCompact Objects as Cosmic Laboratories
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X-ray Transients - Neutron Stars•
X-ray Transients - Black HolesX-ray Transients - Neutron Stars
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X-ray variability correlates with mass transfer rate: H/He disk stability model predicts various states•
X-ray bursts (active and quiescent states)Campana et al
Constraints on Dense Matter
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Equation of state: radius constraints from fitting model atmospheres (flux, temperature, anddistance must be known); gravitational redshift;
mass and its maximum value
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Thermal state of neutron starsOzel et al
EXO 1745-248
RADIO PULSAR DIAGRAM
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Mass measurements of pulsars J 1614-2230 (Demorest et al 2010) and J 0348+ 0432(Antoniadis et al. 2013) yield masses of 1.97 and 2.01 solar masses respectively with
uncertainties of 0.04 solar masses
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Rules out most condensate, hyperon, and quark modelsCase Study: SAX 1808.4-3658
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First accreting millisecond pulsar discovered (2.5 ms)•
Regular outbursts ~ 2 years•
Distance ~3.4-3.6 kpc, implying mean mass transfer rate is known•
Prediction on quiescent flux•
X-ray spectrum during quiescent state iswell fit by a power law without a black body component (kT < 35 eV)
LNS < 1031ergs/s
Heinke et al
X-ray Transients - Black Holes
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High luminosity states characterized by a soft thermal component•
Low luminosity states characterized by power law with photon index ~1.7•
Hard states with the presence of cool gas:soft thermal and reflection component;
evidence of iron features
X-ray properties
States Spectra Timing
Ultra-luminous X-ray Sources
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very soft spectra (< 0.2 keV)•
luminous•
stellar mass black holes accreting super critically?•
intermediate mass black holes (100 - 1000 solar masses) accreting sub critically?⇠ 1039 1042ergs/s
4/3/15, 2:02 PM fg1.h.jpg 661×669 pixels
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Miller et al
X-ray Transients - Black Hole Spin
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Thermal continuum spectrum from the accretion disk•
Broad and skewed fluorescent iron line emission from the disk•
High frequency quasi-periodic oscillations (trapped g-modes, parametric resonances, Lense-Thirring precession)Shafee et al
Summary of Spin Estimates
Source M a/M
A0620-00 6.3-6.9 0.13-0.44
LMC X-3 5.9-9.2 0.09-0.38
J1550-564 8.5-9.7 0.06-0.54
J1655-40 6.0-6.6 0.65-0.75
4U1543-47 8.4-10.4 0.79-0.89 M33 X-7 14.2-17.1 0.81-0.89
LMC X-1 9.4-12.4 0.85-0.97
Cyg X-1 13.8-15.8 > 0.98
1915+105 10-18 > 0.98
Fragos et al
Relativistic Fe line profiles
GRS 1915+105
XTE J1550!564 GRO J1655!40
Cygnus X!1
Miller
High frequency quasi periodic oscillations
Remillard et al
Future Studies
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Probes of dense matter through neutron star properties•
Formation and evolution of black holes in different systems and environments•
Disk physics - investigation of turbulent viscosity& resistivity: importance for disk structure and its variability especially the inner region
