330 research outputs found
Direct Measurement of Thermal Fluctuation of High-Q Pendulum
We achieved for the first time a direct measurement of the thermal
fluctuation of a pendulum in an off-resonant region using a laser
interferometric gravitational wave detector. These measurements have been well
identified for over one decade by an agreement with a theoretical prediction,
which was derived by a fluctuation-dissipation theorem. Thermal fluctuation is
dominated by the contribution of resistances in coil-magnet actuator circuits.
When we tuned these resistances, the noise spectrum also changed according to a
theoretical prediction. The measured thermal noise level corresponds to a high
quality factor on the order of 10^5 of the pendulum.Comment: 10 pages, 4 figure
X-Ray View of the Shock Front in the Merging Cluster Abell 3376 with Suzaku
We report on a Suzaku measurement of the shock feature associated with the
western radio relic in the merging cluster A3376. The temperature profile is
characterized by an almost flat radial shape with kT ~ 4 keV within 0.5 r200
and a rise by about 1 keV inside the radio relic. Across the relic region
(0.6-0.8 r200), the temperature shows a remarkable drop from about 4.7 keV to
1.3 keV. This is a clear evidence that the radio relic really corresponds to a
shock front possibly caused by a past major merger. The observed sharp changes
of the temperature and electron density indicate the Mach number M~3. The
radial entropy profile is flatter than the prediction (r^1.1) of numerical
simulations within 0.5 r200}, and becomes steeper around the relic region.
These observed features and time-scale estimation consistently imply that the
ICM around the radio relic has experienced a merger shock and is in the middle
of the process of dynamical and thermal relaxation.Comment: Accepted for publication in PASJ (12 pages, 6 figures
Practical analysis of 3-D dynamic nonlinear magnetic field using time-periodic finite element method
A practical 3-D finite element method using edge elements for analyzing stationary nonlinear magnetic fields with eddy currents in electric apparatus, in which the flux interlinking the voltage winding is given, has been proposed. The method is applied to the analysis of magnetic fields in the Epstein frame </p
Metallicity of the Fossil Group NGC 1550 Observed with Suzaku
We studied the temperature and metal abundance distributions of the
intra-cluster medium (ICM) in a group of galaxies NGC 1550 observed with
Suzaku. The NGC 1550 is classified as a fossil group, which have few bright
member galaxies except for the central galaxy. Thus, such a type of galaxy is
important to investigate how the metals are enriched to the ICM. With the
Suzaku XIS instruments, we directly measured not only Si, S, and Fe lines but
also O and Mg lines and obtained those abundances to an outer region of ~0.5
r_180 for the first time, and confirmed that the metals in the ICM of such a
fossil group are indeed extending to a large radius. We found steeper gradients
for Mg, Si, S, and Fe abundances, while O showed almost flat abundance
distribution. Abundance ratios of alpha-elements to Fe were similar to those of
the other groups and poor clusters. We calculated the number ratio of type II
to type Ia supernovae for the ICM enrichment to be 2.9 +- 0.5 within 0.1 r_180,
and the value was consistent with those for the other groups and poor clusters
observed with Suzaku. We also calculated metal mass-to-light ratios (MLRs) for
Fe, O and Mg with B-band and K-band luminosities of the member galaxies of NGC
1550. The derived MLRs were comparable to those of NGC 5044 group in the r<0.1
r_180 region, while those of NGC 1550 are slightly higher than those of NGC
5044 in the outer region.Comment: 11 pages, 7 figures, accepted for publication in PAS
Detection of Excess Hard X-ray Emission from the Group of Galaxies HCG62
From the group of galaxies HCG62, we detected an excess hard X-ray emission
in energies above keV with \A SCA. The excess emission is spatially
extended up to from the group center, and somewhat enhanced toward
north. Its spectrum can be represented by either a power-law of photon index
0.8-2.7, or a Bremsstrahlung of temperature keV. In the 2-10 keV range,
the observed hard X-ray flux, erg cm
s, implies a luminosity of erg s for a
Hubble constant of 50 km s Mpc. The emission is thus too luminous
to be attributed to X-ray binaries in the memb er galaxies. We discuss possible
origin of the hard X-ray emission.Comment: 6 pages, 3 Postscript figures, uses emulateapj.sty. Accepted for
publication in the Astrophysical Journal Letter
Thermal-noise-limited underground interferometer CLIO
We report on the current status of CLIO (Cryogenic Laser Interferometer
Observatory), which is a prototype interferometer for LCGT (Large Scale
Cryogenic Gravitational-Wave Telescope). LCGT is a Japanese next-generation
interferometric gravitational wave detector featuring the use of cryogenic
mirrors and a quiet underground site. The main purpose of CLIO is to
demonstrate a reduction of the mirror thermal noise by cooling the sapphire
mirrors. CLIO is located in an underground site of the Kamioka mine, 1000 m
deep from the mountain top, to verify its advantages. After a few years of
commissioning work, we have achieved a thermal-noise-limited sensitivity at
room temperature. One of the main results of noise hunting was the elimination
of thermal noise caused by a conductive coil-holder coupled with a pendulum
through magnets.Comment: 10 pages, 6 figures, Proceedings of the 8th Edoardo Amaldi Conference
on Gravitational Wave
Suzaku and XMM-Newton Observations of the Fornax cluster: Temperature and Metallicity Distribution
Suzaku observed a central region and five offset regions within 0.2 r180 in
the Fornax cluster, a nearby poor cluster, and XMM-Newton mapped the cluster
with 15 pointings out to 0.3 r180. The distributions of O, Mg, Si, S, and Fe in
the intracluster medium (ICM) were studied with Suzaku, and those of Fe and
temperature were studied with XMM. The temperature of the ICM gradually
decreases with radius from 1.3 keV at 0.04 r180 to 1 keV at 0.2-0.3 r180. If
the new solar abundances of Lodders et al. (2003) and a single-temperature
plasma model are adopted, O, Mg, Si, S, and Fe show similar abundances: 0.4-0.6
solar within 0.02-0.2 r180. This Fe abundance is similar to those at 0.1-0.2
r180 in rich clusters and other groups of galaxies. At 0.2-0.3 r180, the Fe
abundance becomes 0.2-0.3 solar. A two-temperature plasma model yields ICM
abundances that are higher by a factor of 1.2-1.5, but gives similar abundance
ratios among O, Mg, Si, S, and Fe. The northern region has a lower ICM
temperature and higher brightness and Fe abundance, whereas the southern region
has a higher ICM temperature and lower brightness and Fe abundance. These
results indicate that the cD galaxy may have traveled from the north because of
recent dynamical evolution. The cumulative oxygen- and iron-mass-to-light
ratios within 0.3 r180 are more than an order of magnitude lower than those of
rich clusters and some relaxed groups of galaxies. Past dynamical evolution
might have hindered the strong concentration of hot gas in the Fornax cluster's
central region. Scatter in the IMLR and similarity in the element abundances in
the ICM of groups and clusters of galaxies indicate early metal synthesis.Comment: 15 pages, 13 figures, accepted for publication in PAS
Reduction of thermal fluctuations in a cryogenic laser interferometric gravitational wave detector
The thermal fluctuation of mirror surfaces is the fundamental limitation for
interferometric gravitational wave (GW) detectors. Here, we experimentally
demonstrate for the first time a reduction in a mirror's thermal fluctuation in
a GW detector with sapphire mirrors from the Cryogenic Laser Interferometer
Observatory at 17\,K and 18\,K. The detector sensitivity, which was limited by
the mirror's thermal fluctuation at room temperature, was improved in the
frequency range of 90\,Hz to 240\,Hz by cooling the mirrors. The improved
sensitivity reached a maximum of at 165\,Hz.Comment: Accepted for publication in Physical Review Letters, 5 pages, 2
figure
Suzaku and Chandra observations of the galaxy cluster RXC J1053.7+5453 with a radio relic
We present the results of Suzaku and Chandra observations of the galaxy
cluster RXC J1053.7+5453 (), which contains a radio relic. The radio
relic is located at the distance of kpc from the X-ray peak toward
the west. We measured the temperature of this cluster for the first time. The
resultant temperature in the center is keV, which is lower than the
value expected from the X-ray luminosity - temperature and the velocity
dispersion - temperature relation. Though we did not find a significant
temperature jump at the outer edge of the relic, our results suggest that the
temperature decreases outward across the relic. Assuming the existence of the
shock at the relic, its Mach number becomes . A possible spatial
variation of Mach number along the relic is suggested. Additionally, a sharp
surface brightness edge is found at the distance of kpc from the
X-ray peak toward the west in the Chandra image. We performed X-ray spectral
and surface brightness analyses around the edge with Suzaku and Chandra data,
respectively. The obtained surface brightness and temperature profiles suggest
that this edge is not a shock but likely a cold front. Alternatively, it cannot
be ruled out that thermal pressure is really discontinuous across the edge. In
this case, if the pressure across the surface brightness edge is in
equilibrium, other forms of pressure sources, such as cosmic-rays, are
necessary. We searched for the non-thermal inverse Compton component in the
relic region. Assuming the photon index , the resultant upper
limit of the flux is for
area in the 0.3-10 keV band, which
implies that the lower limit of magnetic field strength becomes $ 0.7 {\rm \
\mu G}$.Comment: 13page, 8 figures, accepted for publication in PASJ. arXiv admin
note: text overlap with arXiv:1508.0584
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