a 500 ks chandra/hetg observation of ex hya
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
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
Tucson, 2009
Cooling-flow spectrum
non-magnetic CVs, except EX Hya
Photoionized spectrum
Magnetic CVs
Mukai et al (2003)
Comparison with Capella
Calibration uncertainty? Chandra Line Profile Function?
EX Hya line profiles
Tucson, 2009
EX Hya line profiles
Tucson, 2009
Si XIIIFe XVII
Mg XII Fe XVII
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
EX Hya line-based light curves
Tucson, 2009
EX Hya line-based light curves
Allan et al. (1998)
Tall shock, ~ 1RWD
EX Hya line-based light curves
Photoionization model
•We assume a dipole field and the density just above the shock as a parameter, n
0=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
Photoionization model
Tucson, 2009
ϴ α
φ
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
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