196 research outputs found
Search for Near-Infrared Pulsation of the Anomalous X-ray Pulsar 4U 0142+61
We have searched for pulsation of the anomalous X-ray pulsar (AXP) 4U 0142+61
in the K' band ( m) using the fast-readout mode
of IRCS at the Subaru 8.2-m telescope. We found no significant signal at the
pulse frequency expected by the precise ephemeris obtained by the X-ray
monitoring observation with RXTE. Nonetheless, we obtained a best upper limit
of 17% (90% C.L.) for the root-mean-square pulse fraction in the K' band.
Combined with i' band pulsation (Dhillon et al. 2005), the slope of the pulsed
component () was constrained to (90%
C.L.) for an interstellar extinction of .Comment: 11 pages, 3 figures, Accepted for publication in PAS
Suzaku Observation of the Anomalous X-ray Pulsar 1E 1841-045
We report the results of a Suzaku observation of the anomalous X-ray pulsar
(AXP) 1E 1841-045 at a center of the supernova remnant Kes 73. We confirmed
that the energy-dependent spectral models obtained by the previous separate
observations were also satisfied over a wide energy range from 0.4 to ~70 keV,
simultaneously. Here, the models below ~10 keV were a combination of blackbody
(BB) and power-law (PL) functions or of two BBs wit h different temperatures at
0.6 - 7.0 keV (Morii et al. 2003), and that above ~20 keV was a PL function
(Kuiper Hermsen Mendez 2004). The combination BB + PL + PL was found to best
represent the phase-averaged spectrum. Phase-resolved spectroscopy indicated
the existence of two emission regions, one with a thermal and the other with a
non-thermal nature. The combination BB + BB + PL was also found to represent
the phase-averaged spectrum well. However, we found that this model is
physically unacceptable due to an excessively large area of the emission region
of the blackbody. Nonetheless, we found that the temperatures and radii of the
two blackbody components showed moderate correlations in the phase-resolved
spectra. The fact that the same correlations have been observed between the
phase-averaged spectra of various magnetars (Nakagawa et al. 2009) suggests
that a self-similar function can approximate the intrinsic energy spectra of
magnetars below ~10 keV.Comment: Accepted for publication in the PAS
Surgical resection combined with perioperative chemotherapy for a patient with locally recurrent, previously stage IV thymic small-cell carcinoma : A case report
An 83-year-old Japanese man visited our hospital with dyspnea and general fatigue. Computed tomography (CT) revealed a tumor in the anterior mediastinum, bilateral pleural effusion, pericardial fluid, and multiple liver nodules. We performed a CT-guided tumor biopsy, and the patient was diagnosed with thymic small-cell carcinoma, Masaoka–Koga stage classification IVb. The patient received four cycles of carboplatin and etoposide, and all lesions disappeared on CT. However, after 6 months, CT revealed a recurrent tumor in the anterior mediastinum. After one cycle of rechallenge chemotherapy, we performed extended total thymectomy followed by another three cycles of chemotherapy. More than 2.5 years after the last chemotherapy session, the patient’s carcinoma did not recur. Thus, this case suggests that salvage surgery may be a treatment option for local recurrence of thymic carcinoma after complete remission with chemotherapy, even in patients with stage IV cancer
A Spectral Study of the Black Hole Candidate XTE J1752-223 in the High/Soft State with MAXI, Suzaku and Swift
We report on the X-ray spectral analysis of the black hole candidate XTE\
J1752--223 in the 2009--2010 outburst, utilizing data obtained with the
MAXI/Gas Slit Camera (GSC), the Swift/XRT, and Suzaku, which work
complementarily. As already reported by Nakahira et al. (2010) MAXI monitored
the source continuously throughout the entire outburst for about eight months.
All the MAXI/GSC energy spectra in the high/soft state lasting for 2 months are
well represented by a multi-color disk plus power-law model. The innermost disk
temperature changed from 0.7 keV to 0.4 keV and the disk flux
decreased by an order of magnitude. Nevertheless, the innermost radius is
constant at 41 km, where is the
source distance in units of 3.5 kpc and the inclination. The multi-color
disk parameters obtained with the MAXI/GSC are consistent with those with the
Swift/XRT and Suzaku. The Suzaku data also suggests a possibility that the disk
emission is slightly Comptonized, which could account for broad iron-K features
reported previously. Assuming that the obtained innermost radius represents the
innermost stable circular orbit for a non-rotating black hole, we estimate the
mass of the black hole to be 5.510.28 , where the correction for the stress-free inner boundary condition
and color hardening factor of 1.7 are taken into account. If the inclination is
less than 49 as suggested from the radio monitoring of transient jets
and the soft-to-hard transition in 2010 April occurred at 1--4% of Eddignton
luminosity, the fitting of the Suzaku spectra with a relativistic
accretion-disk model derives constraints on the mass and the distance to be
3.1--55 and 2.3--22 {\rm kpc}, respectively. This confirms that the
compact object in XTE J1752--223 is a black hole.Comment: 12 pages including 7 figures and 4 tables, accepted for publication
in PAS
Suzaku Observation of the Anomalous X-ray Pulsar CXOU J164710.2--455216
Suzaku TOO observation of the anomalous X-ray pulsar CXOU J164710.2-455216
was performed on 2006 September 23--24 for a net exposure of 38.8 ks. During
the observation, the XIS was operated in 1/8 window option to achieve a time
resolution of 1 s. Pulsations are clearly detected in the XIS light curves with
a barycenter corrected pulse period of 10.61063(2) s. The XIS pulse profile
shows 3 peaks of different amplitudes with RMS fractional amplitude of ~11% in
0.2--6.0 keV energy band. Though the source was observed with the HXD of
Suzaku, the data is highly contaminated by the nearby bright X-ray source GX
340+0 which was in the HXD field of view. The 1-10 keV XIS spectra are well
fitted by two blackbody components. The temperatures of two blackbody
components are found to be 0.61+/-0.01 keV and 1.22+/-0.06 keV and the value of
the absorption column density is 1.73+/-0.03 x 10^{22} atoms cm^{-2}. The
observed source flux in 1-10 keV energy range is calculated to be 2.6 x
10^{-11} ergs cm^{-2} s^{-1} with significant contribution from the soft
blackbody component (kT = 0.61 keV). Pulse phase resolved spectroscopy of XIS
data shows that the flux of the soft blackbody component consists of three
narrow peaks, whereas the flux of the other component shows a single peak over
the pulse period of the AXP. The blackbody radii changes between 2.2-2.7 km and
0.28-0.38 km (assuming the source distance to be 5 kpc) over pulse phases for
the soft and hard components, respectively. The details of the results obtained
from the timing and spectral analysis is presented.Comment: 16 pages, 9 figures, Accepted for publication in Publications of the
Astronomical Society of Japan (PASJ
Research and development for accuracy improvement of neutron nuclear data on minor actinides
To improve accuracy of neutron nuclear data on minor actinides, a Japanese nuclear data project entitled “Research and development for Accuracy Improvement of neutron nuclear data on Minor ACtinides (AIMAC)” has been implemented. Several independent measurement techniques were developed for improving measurement precision at J-PARC/MLF/ANNRI and KURRI/LINAC facilities. Effectiveness of combining the independent techniques has been demonstrated for identifying bias effects and improving accuracy, especially in characterization of samples used for nuclear data measurements. Capture cross sections and/or total cross sections have been measured for Am-241, Am-243, Np-237, Tc-99, Gd-155, and Gd-157. Systematic nuclear data evaluation has also been performed by taking into account the identified bias effect. Highlights of the AIMAC project are outlined
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