61 research outputs found
Two-Phased Intra-Cluster Medium in the Centaurus Cluster of Galaxies
ASCA and ROSAT data of the Centaurus cluster were analyzed. A central excess
in the radial brightness profile is found in the hard energy band up to 10keV.
This requires a deeper central potential than a King-type one. A double-beta
brightness distribution gives a good account of the data. A deprojected energy
spectrum within a spherical region of radius 30 kpc at the cluster center
indicates that the ICM cannot be isothermal there. Simultaneous fitting of the
three (PSPC, GIS, and SIS) energy spectra extracted from the central 3' region
showed that a two-temperature model that has temperatures of 1.4keV and 4.4keV
and a common metallicity of 1.0 solar with the Galactic absorption gives the
best description to the spectra. A cooling-flow spectral model did not give
satisfactory fit. A 3-dimensional cluster model incorporating the two-phase
picture, the double-beta brightness distribution, and the central metallicity
increase reproduced the overall ASCA and ROSAT data successfully. The derived
spatial distribution of the dark matter deviates from a King-type profile
exhibiting a central excess, which is consistent with the Navvaro-Frenk-White
model. The iron is revealed to be more widely spread than stars, which may have
been caused by energetic supernovae and the motion of the cD galaxy. Since the
derived characteristics of the cool phase including the temperature, angular
extent, gas mass, and metallicity, are on a smooth extension of those of
inter-stellar medium (ISM) of elliptical galaxies, the cool phase can be
regarded as the ISM associated with the cD galaxy. The cool-phase X-ray
emission is presumably sustained by energies dissipated by infalling mass to
the cD galaxy in the course of cluster evolution.Comment: accepted for publication in Ap
Fault Analysis of Space Station DC Power Systems-Using Neural Network Adaptive Wavelets to Detect Faults
This paper describes the application of neural network adaptive wavelets for fault diagnosis of space station power system. The method combines wavelet transform with neural network by incorporating daughter wavelets into weights. Therefore, the wavelet transform and neural network training procedure become one stage, which avoids the complex computation of wavelet parameters and makes the procedure more straightforward. The simulation results show that the proposed method is very efficient for the identification of fault locations
Peculiar outburst of A 0535+26 observed with INTEGRAL, RXTE and Suzaku
A normal outburst of the Be/X-ray binary system A0535+26 has taken place in
August 2009. It is the fourth in a series of normal outbursts that have occured
around the periastron passage of the source, but is unusual by starting at an
earlier orbital phase and by presenting a peculiar double-peaked light curve. A
first "flare" (lasting about 9 days from MJD 55043 on) reached a flux of 440
mCrab. The flux then decreased to less than 220 mCrab, and increased again
reaching 440 mCrab around the periastron at MJD 55057. Target of Opportunity
observations have been performed with INTEGRAL, RXTE and Suzaku. First results
of these observations are presented, with special emphasis on the cyclotron
lines present in the X-ray spectrum of the source, as well as in the pulse
period and energy dependent pulse profiles of the source.Comment: 6 pages, Accepted for publication on PoS, Proceedings of "The Extreme
sky: Sampling the Universe above 10 keV", held in Otranto (Italy) in October
200
ASCA Observation of the Lyman-limit Quasar PKS2145+067
X-ray observation of a famous Lyman-limit quasar PKS2145+067at z_em= 0.990
was carried with ASCA. The source showed a 2-10 keV flux of 1.3 E-11 erg cm^-2
sec^-1 (L_X = 2.5 E46 erg sec^-1 for H_0=50 km s^-1 Mpc^-1) described by a
power-law spectrum with a photon index Gamma=1.63 +/- 0.04 . In the ASCA energy
band, no excess absorption was detected implying the absorption column density
at z_ ab=0.791 was less than 1.6 E21 cm^-2 if absorbing medium had a metal
abundance of 0.5 solar. Comparison with previous Einstein and ROSAT
observations shows that PKS2145+067 has increased its luminosity by a factor of
2--3 between 1991 and 1998.Comment: 15 pages, 3figures, Latex(PASJadd,sty, PASJ95.sty) accepted in PAS
インヨウ サクイン データベース ニ オケル チョシャ ショゾク キカン ノ ゴキサイ ノ ケンキュウ : ニホン ノ ダイガク ト ショザイコク ガ 「ニホン」 ト サレタ ガイコク ノ ダイガク ノ バアイ
引用索引データベースは文献の情報を記録しているが、必ずしもすべて正しくはない。本研究では天文学と材料学の2 分野から、各4 誌の2005 年に掲載された文献、および、その文献を引用した文献を抽出した。これらの文献の国名が日本と記録された16,482 件の所属機関を対象とした。機関情報のうち大学名称の誤記を調査し、58 件を15 の種類に分類した。また、国名の誤記が4 件見つかった。誤記の発生段階を著者・出版者、データベース提供者に区別した。発生段階別の傾向が分かった。Although the citation index database to record information in literatures, it is not necessarily everything correctly. In this study, the literatures were extracted from two fields of astronomy and materials science, literatures was published in from 2005 to current. The number of recorded "Japan" in COUNTRY was 16,482. However, they had been recorded in Japanese universities and foreign universities. Miss records of 58 universities were classified into 15 types. Miss records were identified by an author & a publisher and a database company. Miss records were shown aracteristic
Peculiar Outburst of A 0535+26 Observed with INTEGRAL, RXTE and Suzaku
A normal outburst of the Be/X-ray binary system A0535+26 has taken place in August 2009. It is the fourth in a series of normal outbursts that have occurred around the periastron passage of the source. but is unusual by starting at an earlier orbital phase and by presenting a peculiar double-peaked light curve. A first "flare" (lasting about 9 days from M.ID 55043 on) reached a flux of 440 mCrab. The flux then decreased to less than 220 mCrab. and increased again reaching 440 mCrab around the periastron at MJD 55057. Target of Opportunity observations have been performed with INTEGRAL. RXTE and Suzaku. First results of these observations are presented. with special emphasis on the cyclotron lines present in the X-ray spectrum of the source. as well as in the pulse period and energy dependent pulse profiles of the sourc
Spectral and Timing Analysis of the accretion-powered pulsar 4U 1626-67 observed with Suzaku and NuSTAR
We present an analysis of the spectral shape and pulse profile of the
accretion-powered pulsar 4U 1626-67 observed with Suzaku and NuSTAR during a
spin-up state. The pulsar, which experienced a torque reversal to spin-up in
2008, has a spin period of 7.7 s. Comparing the phase-averaged spectra obtained
with Suzaku in 2010 and with NuSTAR in 2015, we find that the spectral shape
changed between the two observations: the 3-10 keV flux increased by 5% while
the 30-60 keV flux decreased significantly by 35%. Phase-averaged and
phase-resolved spectral analysis shows that the continuum spectrum observed by
NuSTAR is well described by an empirical NPEX continuum with an added broad
Gaussian emission component around the spectral peak at 20 keV. Taken together
with the observed Pdot value obtained from Fermi/GBM, we conclude that the
spectral change between the Suzaku and NuSTAR observations was likely caused by
an increase of the accretion rate. We also report the possible detection of
asymmetry in the profile of the fundamental cyclotron line. Furthermore, we
present a study of the energy-resolved pulse profiles using a new relativistic
ray tracing code, where we perform a simultaneous fit to the pulse profiles
assuming a two-column geometry with a mixed pencil- and fan-beam emission
pattern. The resulting pulse profile decompositions enable us to obtain
geometrical parameters of accretion columns (inclination, azimuthal and polar
angles) and a fiducial set of beam patterns. This information is important to
validate the theoretical predictions from radiation transfer in a strong
magnetic field.Comment: 19 pages, 14 figures, Accepted for publication in ApJ on May 5, 201
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