479 research outputs found
Suzaku Observation of the Intermediate Polar V1223 Sagittarii
We report on the Suzaku observation of the intermediate polar V1223
Sagittarii. Using a multi-temperature plasma emission model with its reflection
from a cold matter, we obtained the shock temperature to be 37.9^{+5.1}_{-4.6}
keV. This constrains the mass and the radius of the white dwarf (WD) in the
ranges 0.82^{+0.05}_{-0.06} solar masses and (6.9+/-0.4)x10^8 cm, respectively,
with the aid of a WD mass-radius relation. The solid angle of the reflector
viewed from the post-shock plasma was measured to be Omega/2pi = 0.91+/-0.26. A
fluorescent iron Kalpha emission line is detected, whose central energy is
discovered to be modulated with the WD rotation for the first time in
magnetic-CVs. Detailed spectral analysis indicates that the line comprises of a
stable 6.4 keV component and a red-shifted component, the latter of which
appears only around the rotational intensity-minimum phase. The equivalent
width (EW) of the former stable component ~80 eV together with the measured
Omega indicates the major reflector is the WD surface, and the shock height is
not more than 7% of the WD radius. Comparing this limitation to the height
predicted by the Aizu model (1973), we estimated the fractional area onto which
the accretion occurs to be < 7x10^{-3}$ of the WD radius, which is the most
severe constraint in non-eclipsing IPs. The red-shifted iron line component, on
the other hand, can be interpreted as emanating from the pre-shock accretion
flow via fluorescence. Its EW (28^{+44}_{-13} eV) and the central energy
(6.30_{-0.05}^{+0.07} keV) at the intensity-minimum phase are consistent with
this interpretation.Comment: 25 pages, 13 figures, accepted for publication in PASJ (Suzaku & MAXI
special issue
The Suzaku Observations of SS Cygni in Quiescence and Outburst
We present results from the Suzaku observations of the dwarf nova SS Cyg in
quiescence and outburst in 2005 November. Owing to high sensitivity of the HXD
PIN detector and high spectral resolution of the XIS, we have determined
parameters of the plasma with unprecedented precision. The maximum temperature
of the plasma in quiescence 20.4 +4.0-2.6 (stat.) +/- 3.0 (sys.) keV is
significantly higher than that in outburst 6.0 +0.2-1.3 keV. The elemental
abundances are close to the solar ones for the medium-Z elements (Si, S, Ar)
whereas they decline both in lighter and heavier elements. Those of oxygen and
iron are 0.46 and 0.37 solar, respectively. That of carbon is exceptionally
high and 2 solar at least. The solid angle of the reflector subtending over the
optically thin thermal plasma is Omega/2\pi = 1.7+/-0.2 (stat.) +/-0.1 (sys.)
in quiescence. A 6.4 keV iron Ka line is resolved into a narrow and broad
components. These facts indicate that both the white dwarf and the accretion
disk contribute to the continuum reflection and the 6.4 keV iron Ka line. We
consider the standard optically thin boundary layer as the most plausible
picture for the plasma configuration in quiescence. The solid angle of the
reflector in outburst Omega/2\pi = 0.9 +0.5-0.4 and a broad 6.4 keV iron line
indicates that the reflection in outburst originates from the accretion disk
and an equatorial accretion belt. From the energy width of the 6.4 keV line, we
consider the optically thin thermal plasma in outburst as being distributed on
the accretion disk like solar coronae.Comment: 28 pages, 15 figures, accepted for publication in PASJ Suzaku 3rd
special issue Pdf of this paper can be downloaded from
http://www.astro.isas.jaxa.jp/~ishida/Papers/sscyg_sub2.pd
- …