Collisional Ionization and Doppler Lines in the Ultra-compact Binary 4U years or X-ray Binaries, Chandra Workshop, July 10-12, 2012, Boston MA

Collisional Ionization and Doppler Lines in the Ultra-compact Binary 4U Ionization properties in X-ray Binaries: Reflection, ADC Emissions, Jets, Discs, …and - Properties of 4U : Torque Reversals, X-rayVariability, Doppler and Fe Lines - Fe Line Fluorescence before and after the 2008 Torque Reversal - Fitting Ionization Models: Photo-ionization vs Collisional Ionization - Possible Interpretations: Fe in the System, Ultracompact CO Disks, Magnetospheres 50 years or X-ray Binaries, Chandra Workshop, July 10-12, 2012, Boston MA

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

X-ray Spectra and Long-term Lightcurve of the Ultra-compact Binary 4U New HETG GTO observations: -Chakrabarty & Schulz 2009 Cycle 11 GO time: OBSIDs 11058, 80 ksec, Jan Camero-Arranz et al Schulz et al. 2012

Continuum Properties of the Ultra-compact Binary 4U before and after Torque Reversal Tbnew (Powerlaw + Bbodyrad): N H = 1.2x10 21 cm -1 A  = ph cm -2 s -1  = 0.80 A bb = 593 (R 2 km / D 2 kpc ) kT bb = 0.20 keV Tbnew (Powerlaw + Bbodyrad): N H = 1.2x10 21 cm -1 (0.2) A  = ph cm -2 s -1  = 1.19 (0.90) A bb = 83 (R 2 km / D 2 kpc ) kT bb = 0.48 keV (0.52) Camero-Arranz et al Schulz et al. 2012

Fe Fluorescence in the Ultra-compact Binary 4U before and after Torqure Reversal Schulz et al. 2012Camero-Arranz et al. 2012

Fe Fluorescence in the Ultra-compact Binary 4U Schulz et al. 2012

Flares and Dips in the New Light Curve of 4U Obsid 11058: Obsid 3504: Schulz et al. 2012

Doppler Lines in the Ultra-compact Binary 4U before and after 2008 Torque Reversal

Doppler Lines in the Ultra-compact Binary 4U Schulz et al. 2012

Ionization Model Fits to the X-ray Spectrum of 4U Photo-ionized modeling: Collisional-ionized modeling:

Aped_density = 13: Collisional Ionization Model Fits to the X-ray Spectrum of 4U Schulz et al. 2012

Pure C/O/Ne disk?: 1)Cannot maintain C I/Ne I/O I : log  > r~10 9 cm 2)Pure C/O disk model predicts T = km (Werner et al. 2006) Model CO Disk Properties in the Ultra-compact Binary 4U

Magnetospheric Accretion Shocks in the Ultra-compact Binary 4U Emission Volumes:

In conclusion we propose the following: Doppler Lines in the Ultra-compact Binary 4U Magnetospheric Accretion Shocks R co = 8.5x10 8 cm R co = R mag V shift ~ 2000 km/s ~ V co V co ~ V shock T jump < 60 MK CO plasma < 20 deg impact V shift = V ion T shock < 10 K

In conclusion we propose the following: Doppler Lines in the Ultra-compact Binary 4U 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 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