97 research outputs found
X-Ray Observations of the W51 Complex with Suzaku
We present a detailed analysis of the X-ray emission from the middle-aged
supernova remnant W51C and star-forming region W51B with Suzaku. The soft X-ray
emission from W51C is well represented by an optically thin thermal plasma in
the non-equilibrium ionization state with a temperature of 0.7 keV. The
elemental abundance of Mg is significantly higher than the solar value. We find
no significant feature of an over-ionized plasma in W51C. The hard X-ray
emission is spatially coincident with the molecular clouds associated with
W51B, overlapping with W51C. The spectrum is represented by an optically thin
thermal plasma with a temperature of 5 keV or a powerlaw model with a
photon index of 2.2. The emission probably has diffuse nature since its
luminosity of 1 erg s in the 0.5-10 keV band cannot be
explained by the emission from point sources in this region. We discuss the
possibility that the hard X-ray emission comes from stellar winds of OB stars
in W51B or accelerated particles in W51C.Comment: 11 pages, 5 figures, accepted for publication in PAS
Economic effects analysis of public investment in road improvement works in Hokkaido. Simulation analysis based on a macro-econometric model of Hokkaido
The objective of this study is to clarify how public investment in road improvement projects over a given analytical period of time has affected Hokkaido`s economic structure on the whole in relation to the industrial economy, prefectural income, household consumption, and commodity prices, through a simulation analysis based on a macro-econometric model. More specifically, our goal is to model both the direct effects achieved through the use of improved roads including the reduction of time-distance coefficients, the reduction of transportation costs and market expansion, and the indirect effects such as enhancement of lifestyles and convenience and influence on other public projects including living area improvement and promotion of regional areas, and to identify these effects quantitatively. Taking data availability into consideration, this study covers a 21-year analysis period covering the years 1976 through 1996. In constructing a quantitative model, the effect flow to be modeled was examined from two perspectives: 1) an effect flow showing the effects of road improvement works on production efficiency and market efficiency; and 2) an effect flow showing the effects of road improvement works on living standards considering convenience and lifestyle improvement. Then we attempted building a model that could indicate the occurrence of these effects in both Flow and Stock contexts. As a result of the simulation analysis, it was clarified that application of road improvement works would bring about pronounced positive economic benefits in tertiary industries, particularly in the transportation-service and wholesale/retail sectors, and greatly expand the prefectural net product on the whole. It was also revealed that these expansion effects would stimulate an increase in the prefectural income and in private final consumption expenditure. Furthermore, a simulation analysis on the economic effects that the expansion of the express-highway network would have on Hokkaido`s entire economy revealed that there would be a large effect particularly on investment and production within the transportation/communication industry and also on the commercial output of the wholesale/retail industry.
Prototyping Hexagonal Light Concentrators Using High-Reflectance Specular Films for the Large-Sized Telescopes of the Cherenkov Telescope Array
We have developed a prototype hexagonal light concentrator for the
Large-Sized Telescopes of the Cherenkov Telescope Array. To maximize the
photodetection efficiency of the focal-plane camera pixels for atmospheric
Cherenkov photons and to lower the energy threshold, a specular film with a
very high reflectance of 92-99% has been developed to cover the inner surfaces
of the light concentrators. The prototype has a relative anode sensitivity
(which can be roughly regarded as collection efficiency) of about 95 to 105% at
the most important angles of incidence. The design, simulation, production
procedure, and performance measurements of the light-concentrator prototype are
reported.Comment: 21 pages, 14 figures, accepted for publication in JINS
Measuring the Broad-band X-Ray Spectrum from 400 eV to 40 keV in the Southwest Part of the Supernova Remnant RX J1713.7-3946
We report on results from Suzaku broadband X-ray observations of the
southwest part of the Galactic supernova remnant (SNR) RX J1713.7-3946 with an
energy coverage of 0.4-40 keV. The X-ray spectrum, presumably of synchrotron
origin, is known to be completely lineless, making this SNR ideally suited for
a detailed study of the X-ray spectral shape formed through efficient particle
acceleration at high speed shocks. With a sensitive hard X-ray measurement from
the HXD PIN on board Suzaku, we determine the hard X-ray spectrum in the 12--40
keV range to be described by a power law with photon index Gamma = 3.2+/- 0.2,
significantly steeper than the soft X-ray index of Gamma = 2.4+/- 0.05 measured
previously with ASCA and other missions. We find that a simple power law fails
to describe the full spectral range of 0.4-40 keV and instead a power-law with
an exponential cutoff with hard index Gamma = 1.50+/- 0.09 and high-energy
cutoff epsilon_c = 1.2+/- 0.3 keV formally provides an excellent fit over the
full bandpass. If we use the so-called SRCUT model, as an alternative model, it
gives the best-fit rolloff energy of epsilon_{roll} = 0.95+/- 0.04 keV.
Together with the TeV gamma-ray spectrum ranging from 0.3 to 100 TeV obtained
recently by HESS observations, our Suzaku observations of RX J1713.7-3946
provide stringent constraints on the highest energy particles accelerated in a
supernova shock.Comment: 11 pages, 11 figures, accepted for publication in Publications of the
Astronomical Society of Japan (PASJ
Discovery of Extended X-Ray emission from the unidentified TeV source HESS J1614-518 using the Suzaku Satellite
We report the Suzaku results of HESS J1614-518, which is the brightest
extended TeV gamma-ray source discovered in the Galactic plane survey conducted
using the H.E.S.S. telescope. We discovered three X-ray objects in the field of
view of the X-ray Imaging Spectrometer (XIS), which were designated as Suzaku
J1614-5141 (src A), Suzaku J1614-5152 (src B), and Suzaku J1614-5148 (src C).
Src A is an extended source located at the peak position of HESS J1614-518, and
therefore it is a plausible counterpart to HESS J1614-518. The X-ray flux in
the 2-10 keV band is 5e-13 erg/s/cm^2, which is an order of magnitude smaller
than the TeV flux. The photon index is 1.7, which is smaller than the canonical
value of synchrotron emissions from high-energy electrons found in some
supernova remnants. These findings present a challenge to models in which the
origin of the TeV emission is the inverse Compton scattering of the cosmic
microwave background by accelerated electrons that emit X-rays via synchrotron
emission. Src B is located at a relatively dim region in the TeV band image;
however, its hydrogen column density is the same as that of src A. Therefore,
src B may also be physically related to HESS J1614-518. Src C is a foreground
late-type B star. We also discovered a soft extended X-ray emission near HESS
J1614-518.Comment: Accepted for publication in PASJ vol. 60 Suzaku Special Issue
Optical and Near-Infrared Photometry of Nova V2362 Cyg : Rebrightening Event and Dust Formation
We present optical and near-infrared (NIR) photometry of a classical nova,
V2362 Cyg (= Nova Cygni 2006). V2362 Cyg experienced a peculiar rebrightening
with a long duration from 100 to 240 d after the maximum of the nova. Our
multicolor observation indicates an emergence of a pseudophotosphere with an
effective temperature of 9000 K at the rebrightening maximum. After the
rebrightening maximum, the object showed a slow fading homogeneously in all of
the used bands for one week. This implies that the fading just after the
rebrightening maximum ( less or equal 1 week ) was caused by a slowly shrinking
pseudophotosphere. Then, the NIR flux drastically increased, while the optical
flux steeply declined. The optical and NIR flux was consistent with blackbody
radiation with a temperature of 1500 K during this NIR rising phase. These
facts are likely to be explained by dust formation in the nova ejecta. Assuming
an optically thin case, we estimate the dust mass of 10^(-8) -- 10^(-10)
M_solar, which is less than those in typical dust-forming novae. These results
support the senario that a second, long-lasting outflow, which caused the
rebrightening, interacted with a fraction of the initial outflow and formed
dust grains.Comment: 6 pages, 4 figures, 2010, PASJ, 62, 1103--1108, in pres
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