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A 500 ks Chandra/HETG observation of EX Hya

A 500 ks Chandra/HETG observation of EX Hya. Gerardo J. M. Luna (SAO) ‏ Nancy Brickhouse (SAO) ‏ John Raymond (SAO) ‏ Chris Mauche (LLNL) ‏ Daniel Proga (UNLV) ‏ Danny Steeghs (University of Warwick) ‏. Tucson, 2009. EX Hya. - X-rays observations : 50 ks Chandra/HETG in 2000.

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A 500 ks Chandra/HETG observation of EX Hya

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  1. A 500 ks Chandra/HETG observation of EX Hya Gerardo J. M. Luna (SAO)‏ Nancy Brickhouse (SAO)‏ John Raymond (SAO)‏ Chris Mauche (LLNL)‏ Daniel Proga (UNLV)‏ Danny Steeghs (University of Warwick)‏ Tucson, 2009

  2. EX Hya • -X-rays observations: • 50 ks Chandra/HETG in 2000 Mukai et al (2003)‏ Photoionized spectrum Magnetic CVs Cooling-flow spectrum non-magnetic CVs, except EX Hya Tucson, 2009

  3. EX Hya line profiles Comparison with Capella Calibration uncertainty? Chandra Line Profile Function? Tucson, 2009

  4. EX Hya line profiles Si XIII Fe XVII Mg XII Fe XVII Tucson, 2009

  5. EX Hya lines density diagnostic • We measure the density using 3 different line ratios (f/i), Fe XXII, Fe XVII and Si XIII. The values agree with previous measurements (Mauche et al 2005). Tucson, 2009

  6. EX Hya line-based light curves Tucson, 2009

  7. EX Hya line-based light curves Tall shock, ~ 1RWD Allan et al. (1998)

  8. EX Hya line-based light curves

  9. Photoionization model • We assume a dipole field and the density just above the shock as a parameter, n0=n14 1014 cm-3 • As n0 goes from 1 to 10, the area of the accretion spot goes from 0.143-0.045 RWD and the height of the shock goes from 0.459 to 0.046 RWD. • For scales near the accretion spot size, the dilution factor of the X-ray radiation drops rapidly as (rspot/(r-1))2. The ionization parameters drops quickly close to the accretion spot. • For large height it drops as r-2 and the ionization parameter rise slowly as r1/2. Tucson, 2009

  10. Photoionization model ϴ α φ Tucson, 2009

  11. Photoionization model • Add compressional heating • Escape probabilities and collisional quenching • Continuum radiative transfer along the column • Line radiative transfer along the column • Accurate Hα and UV fluxes. Tucson, 2009

  12. Synthesis • A long exposure in X-rays has allowed us to observe for the first time new features in the accretion column of EX Hya. • High signal-to-noise line profiles revealed a photoionization component with FWHM~1600 km/s. • Preliminary photoionization models show that OVIII, Si XIV, Mg XII are formed close to the shock, and this is confirmed by their modulation at the spin period. • We measure more accurately density diagnostic lines ratios with the unprecedented quality of this dataset. Tucson, 2009

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