874 research outputs found
Suzaku observations of subhalos in the Coma cluster
We observed three massive subhalos in the Coma cluster with {\it Suzaku}.
These subhalos, labeled "ID 1", "ID 2", and "ID 32", were detected with a
weak-lensing survey using the Subaru/Suprime-Cam (Okabe et al. 2014a), and are
located at the projected distances of 1.4 , 1.2 , and 1.6
from the center of the Coma cluster, respectively. The subhalo "ID 1"
has a compact X-ray excess emission close to the center of the weak-lensing
mass contour, and the gas mass to weak-lensing mass ratio is about 0.001. The
temperature of the emission is about 3 keV, which is slightly lower than that
of the surrounding intracluster medium (ICM) and that expected for the
temperature vs. mass relation of clusters of galaxies. The subhalo "ID 32"
shows an excess emission whose peak is shifted toward the opposite direction
from the center of the Coma cluster. The gas mass to weak-lensing mass ratio is
also about 0.001, which is significantly smaller than regular galaxy groups.
The temperature of the excess is about 0.5 keV and significantly lower than
that of the surrounding ICM and far from the temperature vs. mass relation of
clusters. However, there is no significant excess X-ray emission in the "ID 2"
subhalo. Assuming an infall velocity of about 2000 , at the
border of the excess X-ray emission, the ram pressures for "ID 1" and "ID 32"
are comparable to the gravitational restoring force per area. We also studied
the effect of the Kelvin-Helmholtz instability to strip the gas. Although we
found X-ray clumps associated with the weak-lensing subhalos, their X-ray
luminosities are much lower than the total ICM luminosity in the cluster
outskirts.Comment: 19 pages, 8 figures, ApJ in pres
Suzaku observations of the Hydra A cluster out to the virial radius
We report Suzaku observations of the northern half of the Hydra A cluster out
to ~1.4 Mpc, reaching the virial radius. This is the first Suzaku observations
of a medium-size (kT ~3 keV) cluster out to the virial radius. Two observations
were conducted, north-west and north-east offsets, which continue in a filament
direction and a void direction of the large-scale structure of the Universe,
respectively. The X-ray emission and distribution of galaxies elongate in the
filament direction. The temperature profiles in the two directions are mostly
consistent with each other within the error bars and drop to 1.5 keV at 1.5
r_500. As observed by Suzaku in hot clusters, the entropy profile becomes
flatter beyond r_500, in disagreement with the r^1.1 relationship that is
expected from accretion shock heating models. When scaled with the average
intracluster medium (ICM) temperature, the entropy profiles of clusters
observed with Suzaku are universal and do not depend on system mass. The
hydrostatic mass values in the void and filament directions are in good
agreement, and the Navarro, Frenk, and White universal mass profile represents
the hydrostatic mass distribution up to ~ 2 r_500. Beyond r_500, the ratio of
gas mass to hydrostatic mass exceeds the result of the Wilkinson microwave
anisotropy probe, and at r_100, these ratios in the filament and void
directions reach 0.4 and 0.3, respectively. We discuss possible deviations from
hydrostatic equilibrium at cluster outskirts. We derived radial profiles of the
gasmass- to-light ratio and iron-mass-to-light ratio out to the virial radius.
Within r_500, the iron-mass-to-light ratio of the Hydra A cluster was compared
with those in other clusters observed with Suzaku.Comment: 16 pages, 15 figures; Accepted for publication in PAS
Fabrication of Planar Power Inductor for Embedded Passives in LSI Package for Hundreds Megahertz Switching DC–DC Buck Converter
Recently, research and development of integrated low-voltage dc-dc converter to LSIs has been active. In order to realize such integrated dc power supply, power magnetic devices must be integrated in it. The authors have fabricated planar power inductor embedded in LSI package for hundreds megahertz switching dc-dc buck converter. In this study, two types of planar power inductors have been fabricated: one was spin-sprayed Zn-ferrite thick film magnetic core inductor, and the other was composite magnetic core (Fe-based amorphous/polyimide) inductor. Footprint of the fabricated inductors was 850 x 850 mu m(2), their inductance was about 10 nH, and the quality factor Q was about 20 at 100 MHz. The rating current which depends on the superimposed dc characteristic was at least up to 2 A.ArticleIEEE TRANSACTIONS ON MAGNETICS. 47(10):3204-3207 (2011)journal articl
Fabrication of Planar Power Inductor for Embedded Passives in LSI Package for Hundreds Megahertz Switching DC-DC Buck Converter
Recently, research and development of integrated low-voltage dc-dc converter to LSIs has been active. In order to realize such integrated dc power supply, power magnetic devices must be integrated in it. The authors have fabricated planar power inductor embedded in LSI package for hundreds megahertz switching dc-dc buck converter. In this study, two types of planar power inductors have been fabricated: one was spin-sprayed Zn-ferrite thick film magnetic core inductor, and the other was composite magnetic core (Fe-based amorphous/polyimide) inductor. Footprint of the fabricated inductors was 850 x 850 mu m(2), their inductance was about 10 nH, and the quality factor Q was about 20 at 100 MHz. The rating current which depends on the superimposed dc characteristic was at least up to 2 A.ArticleIEEE TRANSACTIONS ON MAGNETICS. 47(10):3204-3207 (2011)journal articl
Embedded Planar Power Inductor in an Organic Interposer for Package-Level DC Power Grid
To realize the basic technology of a package-level dc power grid for the next generation power delivery to large scale integrated circuits (LSIs), two types of planar spiral inductors embedded in an organic interposer, for several tens of megahertz switching power supply integrated in LSI package, have been proposed. One is a Zn-Fe ferrite core spiral inductor, and another is a hybrid core spiral inductor, with quasi closed magnetic circuit consisting of the bottom Zn-Fe ferrite core and top carbonyl-iron/epoxy composite core. In this paper, the two types of planar spiral inductors have been fabricated and evaluated. From the experimental results, it was found that the hybrid core planar spiral inductor exhibited higher Q-factor and larger rating dc current than the Zn-Fe ferrite core inductor.ArticleIEEE TRANSACTIONS ON MAGNETICS. 50(11):8401304 (2014)journal articl
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