108 research outputs found
The origin of an extended X-ray emission apparently associated with the globular cluster 47 Tucanae
Using the Suzaku X-ray Imaging Spectrometer, we performed a 130 ks
observation of an extended X-ray emission, which was shown by ROSAT and Chandra
observations to apparently associate with the globular cluster 47 Tucanae. The
obtained keV spectrum was successfully fitted with a redshifted thin
thermal plasma emission model whose temperature and redshift are
keV (at the rest frame) and , respectively.
Derived parameters, including the temperature, redshift, and luminosity,
indicate that the extended X-ray source is a background cluster of galaxies,
and its projected location falls, by chance, on the direction of the proper
motion of 47 Tucanae.Comment: 9 pages, 9 figures, accepted for publication in PASJ Vol. 61 No.
Interfacial Fe segregation and its influence on magnetic properties of CoFeB/MgFeO multilayers
We investigated the effect of Fe segregated from partially Fe-substituted MgO
(MgFeO) on the magnetic properties of CoFeB/MgFeO multilayers. X-ray
photoelectron spectroscopy (XPS) as well as magnetic measurements revealed that
the segregated Fe was reduced to metal and exhibited ferromagnetism at the
CoFeB/MgFeO interface. The CoFeB/MgFeO multilayer showed more than 2-fold
enhancement in perpendicular magnetic anisotropy (PMA) energy density compared
with a standard CoFeB/MgO multilayer. The PMA energy density was further
enhanced by inserting an ultrathin MgO layer in between CoFeB and MgFeO layers.
Ferromagnetic resonance measurement also revealed a remarkable reduction of
magnetic damping in the CoFeB/MgFeO multilayers.Comment: 15 pages, 5 figure
Suzaku and Optical Spectroscopic Observations of SS 433 in the 2006 April Multiwavelength Campaign
We report results of the 2006 April multi-wavelengths campaign of SS 433,
focusing on X-ray data observed with Suzaku at two orbital phases (in- and
out-of- eclipse) and simultaneous optical spectroscopic observations. By
analyzing the Fe25 K_alpha lines originating from the jets, we detect rapid
variability of the Doppler shifts, dz/dt ~ 0.019/0.33 day^-1, which is larger
than those expected from the precession and/or nodding motion. This phenomenon
probably corresponding to "jitter" motions observed for the first time in
X-rays, for which significant variability both in the jet angle and intrinsic
speed is required. From the time lag of optical Doppler curves from those of
X-rays, we estimate the distance of the optical jets from the base to be ~(3-4)
\times 10^14 cm. Based on the radiatively cooling jet model, we determine the
innermost temperature of the jets to be T_0 = 13 +/- 2 keV and 16 +/- 3 keV
(the average of the blue and red jets) for the out-of-eclipse and in-eclipse
phase, respectively, from the line intensity ratio of Fe25 K_alpha and Fe26
K_alpha. While the broad band continuum spectra over the 5--40 keV band in
eclipse is consistent with a multi-temperature bremsstrahlung emission expected
from the jets, and its reflection component from cold matter, the
out-of-eclipse spectrum is harder than the jet emission with the base
temperature determined above, implying the presence of an additional hard
component.Comment: 12 pages, 15 figures, accepted for publication in PAS
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