173 research outputs found
Evidence for Recombining Plasma in the Supernova Remnant G346.6-0.2
We present the Suzaku results of the supernova remnant (SNR) G346.6-0.2. The
X-ray emission has a center-filled morphology with the size of 6' x 8' within
the radio shell. Neither an ionization equilibrium nor non-equilibrium
(ionizing) plasma can reproduce the spectra remaining shoulder-like residuals
in the 2-4 keV band. These structures are possibly due to recombination of free
electrons to the K-shell of He-like Si and S. The X-ray spectra are well fitted
with a plasma model in a recombination dominant phase. We propose that the
plasma was in nearly full ionized state at high temperature of 5 keV, then the
plasma changed to a recombining phase due to selective cooling of electrons to
lower temperature of 0.3 keV. G346.6-0.2 would be in an epoch of the
recombining phase.Comment: Accepted for publication in PAS
Confirmation of dust scattering echo around MAXI J1421-613 by Swift observation
MAXI J1421-613 is an X-ray burster discovered by Monitor of All-sky X-ray
Image (MAXI) on 9 January 2014 and is considered to be a low-mass X-ray binary.
A previous study analyzing follow-up observation data obtained by Suzaku on 31
January to 3 February 2014 reported that an annular emission of ~3'-9' radius
was found around the transient source. The most plausible origin of the annular
emission is a dust scattering echo by the outburst of MAXI J1421-613. In this
paper, we confirm the annular emission by analyzing the data of the Swift
follow-up observation which was conducted by the photon counting mode on 18
January 2014. In a radial profile, we found an annular emission at ~2'.5-4'.5.
Its spectrum was well explained by an absorbed power law, and the photon index
was higher than that of MAXI J1421-613 itself by delta Gamma~2. The flux and
radius of the annular emission observed by Swift are explained by dust
scattering of the same outburst as is responsible for the annular emission
observed by Suzaku. Assuming that the dust layer causing the annular emission
found by Swift is located at the same position as the CO cloud in front of MAXI
J1421-613, the distance to the transient source was estimated to be ~3 kpc,
which is consistent with the value estimated by the previous study of Suzaku.Comment: 7 pages, 3 figures, accepted for publication in Advances in Space
Researc
X-Ray Reflection Nebulae with Large Equivalent Widths of Neutral Iron Ka Line in the Sgr C Region
This paper reports on the first results of the Suzaku observation in the Sgr
C region. We detected four diffuse clumps with strong line emission at 6.4keV,
Ka from neutral or low-ionized Fe. One of them, M359.38-0.00, is newly
discovered with Suzaku. The X-ray spectra of the two bright clumps,
M359.43-0.07 and M359.47-0.15, after subtracting the Galactic center diffuse
X-ray emission (GCDX), exhibit strong Ka line from FeI with large equivalent
widths (EWs) of 2.0-2.2keV and clear Kb of FeI. The GCDX in the Sgr C region is
composed of the 6.4keV- and 6.7keV-associated components. These are
phenomenologically decomposed by taking relations between EWs of the 6.4keV and
6.7keV lines. Then the former EWs against the associated continuum in the
bright clump regions are estimated to be 2.4(+2.3_-0.7)keV. Since the two
different approaches give similar large EWs of 2keV, we strongly suggest that
the 6.4keV clumps in the Sgr C region are due to X-ray reflection/fluorescence
(the X-ray reflection nebulae).Comment: Accepted for publication in PAS
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