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The Nature of the Doppler Lines in the Ultra-compact Binary

The Nature of the Doppler Lines in the Ultra-compact Binary 4U1626-67. Doppler Lines and Fe Fluorescence in the Ultra-compact Binary 4U1626-67. Previous HETG GTO observations:

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The Nature of the Doppler Lines in the Ultra-compact Binary

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  1. The Nature of the Doppler Lines in the Ultra-compact Binary 4U1626-67

  2. Doppler Lines and Fe Fluorescence in the Ultra-compact Binary 4U1626-67 Previous HETG GTO observations: - Schulz et al. 2001: Double Peaked X-ray Lines from the O/Ne-rich Accretion Disk in 4U 1626-67: OBSIDs 104, 39 ksec - Krauss et al. 2007: High Resolution X-ray Spectroscopy of the Ultra-compact LMXB Pulsar 4U 1626-67: OBSIDs 104, 39 ksec 3504, 97 ksec

  3. Doppler Lines and Fe Fluorescence in the Ultra-compact Binary 4U1626-67 • New HETG GTO observations: • Chakrabarty & Schulz 2009 Cycle 11 GO time: OBSIDs 11058, 80 ksec, Jan 14. 2010

  4. Doppler Lines and Fe Fluorescence in the Ultra-compact Binary 4U1626-67 • Tbnew (Powerlaw + Bbodyrad): • NH = 1.2x1021 cm-1 • AG = 0.0084 ph cm-2 s-1 • = 0.80 • Abb = 593 (R2km / D2kpc) • kTbb = 0.20 keV • Tbnew (Powerlaw + Bbodyrad): • NH = 1.2x1021 cm-1 • AG = 0.0384 ph cm-2 s-1 • = 1.19 • Abb = 83 (R2km / D2kpc) • kTbb = 0.48 keV

  5. Flares and Dips in the New Light Curve of 4U1626-67 Obsid 11058: Obsid 3504:

  6. Doppler Lines in the Ultra-compact Binary 4U1626-67

  7. Doppler Lines in the Ultra-compact Binary 4U1626-67

  8. Ionization Model Fits to the X-ray Spectrum of 4U1626-67 Photo-ionized modeling: Collisional-ionized modeling:

  9. Collisional Ionization Model Fits to the X-ray Spectrum of 4U1626-67 Aped_density = 13:

  10. Doppler Lines and Fe Fluorescence in the Ultra-compact Binary 4U1626-67 Pure C/O/Ne disk?: Cannot maintain C I/Ne I/O I : log x > 2 @ r~109 cm Pure C/O disk model predicts T = 28000 K @ 20000 km (Werner et al. 2006)

  11. Magnetospheric Accretion Shocks in the Ultra-compact Binary 4U1626-67 Emission Volumes:

  12. Doppler Lines in the Ultra-compact Binary 4U1626-67 In conclusion we propose the following: Rco = 8.5x108 cm Rco = Rmag Vshift ~ 2000 km/s ~ Vco Vco ~ Vshock Tjump < 60 MK CO plasma < 20 deg impact Vshift = Vion Tshock < 10 K Magnetospheric Accretion Shocks

  13. Doppler Lines in the Ultra-compact Binary 4U1626-67 In conclusion we propose the following: • The light curve before torque reversal is featureless. The light curve after torque reversal shows enhance variability which includes type II flaring, intensity dips, and periods of quiescence. • The X-ray flux at the time of the observation in 2009 is at about the same level as it was in 1994. • The X-ray continuum after torque reversal is fit by the same spectrum as before, however with a higher blackbody temperature and a smaller emission radius . • The spectrum shows a narrow Fe K fluorescence line, which was not observed before torque reversal. • A photo-ionized plasma cannot fit the Ne and O Doppler line emissions. • The large ratio between the Ne X Lα line and the upper limit to the Ne X Lβ line rules out significant contributions due to resonance scattering . • A collisions ionized plasma fits both Ne and O line ratios very well with enhanced plasma densities and plasma temperature between 1 MK and 10 MK. Magnetospheric Accretion Shocks

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