263 research outputs found
Development of a Si/CdTe semiconductor Compton telescope
We are developing a Compton telescope based on high resolution Si and CdTe
imaging devices in order to obtain a high sensitivity astrophysical observation
in sub-MeV gamma-ray region. In this paper, recent results from the prototype
Si/CdTe semiconductor Compton telescope are reported. The Compton telescope
consists of a double-sided Si strip detector (DSSD) and CdTe pixel detectors,
combined with low noise analog LSI, VA32TA. With this detector, we obtained
Compton reconstructed images and spectra from line gamma-rays ranging from 81
keV up to 356 keV. The energy resolution is 3.8 keV and 7.9 keV at 122 keV and
356 keV, respectively, and the angular resolution is 9.9 degrees and 5.7
degrees at 122 keV and 356 keV, respectively.Comment: 12 pages, 14 figures, submitted to SPIE conference proceedings vol.
5501, "High-Energy Detectors in Astronomy", Glasgow UK, 6/21-6/24 200
Unraveling the Nature of Unidentified High Galactic Latitude Fermi/LAT Gamma-ray Sources with Suzaku
We report on the results of deep X-ray follow-up observations of four
unidentified Fermi/LAT gamma-ray sources at high Galactic latitudes using
Suzaku. The studied objects were detected with high significance during the
first 3 months of Fermi/LAT operation, and subsequently better localized in the
Fermi/LAT 1 year catalog (1FGL). Possible associations with pulsars and active
galaxies have subsequently been discussed, and our observations provide an
important contribution to this debate. In particular, an X-ray point source was
found within the 95% confidence error circle of 1FGL J1231.1-1410. X-ray
spectrum is well-fitted by a blackbody with an additional power-law. This
supports the recently claimed identification of this source with a millisecond
pulsar (MSP) PSR J1231-1411. Concerning 1FGL J1311.7-3429, two X-ray sources
were found within the LAT error circle. Even though the X-ray spectral and
variability properties were accessed, their nature and relationship with the
gamma-ray source remain uncertain. We found several weak X-ray sources in the
field of 1FGL J1333.2+5056, one coinciding with CLASS J1333+5057. We argue the
available data are consistent with the association between these two objects.
Finally, we have detected an X-ray source in the vicinity of 1FGL J2017.3+0603.
This object was recently suggested to be associated with a newly discovered MSP
PSR J2017+0603, because of the spatial-coincidence and the gamma-ray pulse
detection. We have only detected the X-ray counterpart of the CLASS J2017+0603,
while we determined an X-ray flux upper limit at the pulsar position. All in
all, our studies indicate while a significant fraction of unidentified high
Galactic latitude gamma-ray sources is related to the pulsar and blazar
phenomena, associations with other classes of astrophysical objects are still
valid options.Comment: Accepted for publication in the Ap
A Suzaku Observation of the Low-Ionization Fe-Line Emission from RCW 86
The newly operational X-ray satellite Suzaku observed the southwestern
quadrant of the supernova remnant (SNR) RCW 86 in February 2006 to study the
nature of the 6.4 keV emission line first detected with the Advanced Satellite
for Cosmology and Astronomy (ASCA). The new data confirm the existence of the
line, localizing it for the first time; most of the line emission is adjacent
and interior to the forward shock and not at the locus of the continuum hard
emission. We also report the first detection of a 7.1 keV line that we
interpret as the K-beta emission from low-ionization iron. The Fe-K line
features are consistent with a non-equilibrium plasma of Fe-rich ejecta with
n_{e}t <~ 10^9 cm^-3 s and kT_{e} ~ 5 keV. This combination of low n_{e}t and
high kT_{e} suggests collisionless electron heating in an SNR shock. The Fe
K-alpha line shows evidence for intrinsic broadening, with a width of 47
(34--59) eV (99% error region). The difference of the spatial distributions of
the hard continuum above 3 keV and the Fe-K line emission support a synchrotron
origin for the hard continuum.Comment: 6 pages with 6 figures. Accepted for PASJ Suzaku Special Issue (vo.
58, sp.1
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