X−ray Spectral Modeling for Low−Mass X−ray...
Transcript of X−ray Spectral Modeling for Low−Mass X−ray...
X−ray Spectral Modeling for Low−Mass X−ray Binaries
Mario Jimenez−Garate (MIT)
Collaborators: John Raymond (CfA) Duane Liedahl (LLNL)
Jimenez−Garate XRB 02
Photoionized Plasma Models
Particle−photon interactions
Heating = CoolingRecombination rate = Photoionization rate
Radiative cascade
Radiativerecombination
time
Photoionization
L
ner2
ξ =Ionizationparameter
Jimenez−Garate XRB 02
Low−Mass X−ray Binaries withBroad X−ray Line Emission
Hypothesis: Kepler−velocity
broadened lines from
the accretion disk
EXO 0748−676: eclipses, bursts, dips Porb= 3.8 hr, M2 ~ 0.4−0.8 Msun
4U1626: X−ray pulsarPorb= 42 min, M2 < 0.1 Msun
Jimenez−Garate XRB 02
HETGSchulz et al.(2001)
HETG
Centrally Illuminated AccretionDisk Atmosphere and Corona
Radiation TransferGravity
Hydrostatic EquilibriumThermal Balance
Ionization Equilibrium
4 π
Boundary conditions
θ
=
0
Adaptivezone grid
Isothermaldisk, τ>>1
z phot
Gravityz cor
m p
ρcor k T compton
µP =
r
Hot corona
Disk midplane
= 0
Atmosphere
Photosphere
2
Lx
m pµk Tphot photρ
P =
T = T phot
F
F
νF
ν
dν
F
z
dν
Jimenez−Garate XRB 02
X−rays
Gascolumn
Fνd
Fνu
Fν
DiskNeutron star
r
z
Corona
θα
R*
Schematic of exact geometryβ
α
LX = 1037, 1038 erg s−1
Centrally Illuminated AccretionDisk Atmosphere and Corona
Jimenez−Garate XRB 02
Vertical Ionization Structure
Atmosphere thickened by Irradiation
Centrally Illuminated Accretion Disk
Jimenez−Garate XRB 02
A Thick Atmosphere and Corona
Centrally Illuminated AccretionDisk Atmosphere and Corona
Synthetic X−ray Spectrum vs. Absorption NH of Neutron Star Flux
N = 10 cm21
22
−2H*
24N = 10 cm−2H*
N cm−2H* = 5 x 10
(a)
(b)
(c)
Jimenez−Garate XRB 02
Centrally Illuminated AccretionDisk Atmosphere and Corona
Synthetic Profilesand Plasma Diagnostics
Jimenez−Garate XRB 02
O VII i
r
HETG Data (EXO 0748−676)
Line profiles probe radial Atmosperic Changes
Centrally Illuminated AccretionDisk Atmosphere and Corona
Comparison with Spectral Data
Model
HETG Data (EXO 0748−676)
Jimenez−Garate XRB 02
Instr
?
?
Dips vs.No Dip
Dips
Centrally Illuminated AccretionDisk Atmosphere and Corona
Comparison with Spectral Data
Model
Data
Cottam et al. (2001)
XMM−Newton RGS, 30ks
EXO 0748−67
Jimenez−Garate XRB 02
EXO 0748−676: eclipses, bursts, dips Porb= 3.8 hr, M2 ~ 0.4−0.8 Msun
Cottam et al. (2001)MEGHEG
MEG / 50 ks simulation
Jimenez−Garate XRB 02
Centrally Illuminated AccretionDisk Atmosphere and Corona
Narrow Line Emission from a Disk Bulge in
4U 1822−37: X−ray pulsar, ADC, Porb= 5.6 hr
Comparison with Spectral Data
Corona
Hot atmosphere
Photosphereand warm atmosphere
Opticallythick disk
Dippers
No lines
i~60°°
i~75°°
i~80°°
Partial eclipses &coronal sources
Broad lines
Weaker, narrow lines
i~60°°
i~75°°
i~80°°Broader lines
Dips & total eclipses
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Centrally Illuminated AccretionDisk Atmosphere and Corona
Inclination Dependenceof X−ray Recombination Emission
Lines from X−raypulsar disks?
Conclusions
Jimenez−Garate XRB 02
Strong Theoretical Evidence for Accretion Disk Atmosphereand Corona present in 0.1−1Ledd neutron star LMXB
Strong Observational Evidence for ’Thick’ Diskin neutron star LMXB
Plasma Diagnostics probe Atmosphere Te,ne
Atmosphere thickened by irradiation (feedback)
Strong Inclination Dependence of X−ray Recombination Emission
Line profiles probe radial Atmosperic Structure
Weak Coupling between Atmosphere and Disk!
Future Work
Jimenez−Garate XRB 02
Eclipsing Dippers EXO 0748−676, Hercules X−1 (Emission & Transmission Spectroscopy)
LMXB dipper 4U1254−690 (Disk Emission search)
Line Transfer and Relativistic Compton Scattering(Monte Carlo)
Black Hole Accretion Disks
Observations:
Theory:
Collaborators: Duane Liedahl, Chris Mauche (LLNL),John Raymond (CfA)