206 research outputs found
Expected Hard X-Ray and Soft Gamma-Ray from Supernovae
High energy emissions from supernovae (SNe), originated from newly formed
radioactive species, provide direct evidence of nucleosynthesis at SN
explosions. However, observational difficulties in the MeV range have so far
allowed the signal detected only from the extremely nearby core-collapse SN
1987A. No solid detection has been reported for thermonuclear SNe Ia, despite
the importance of the direct confirmation of the formation of 56Ni, which is
believed to be a key ingredient in their nature as distance indicators. In this
paper, we show that the new generation hard X-ray and soft gamma-ray
instruments, on board Astro-H and NuStar, are capable of detecting the signal,
at least at a pace of once in a few years, opening up this new window for
studying SN explosion and nucleosynthesis.Comment: 4 pages, 3 figures and 1 table. Invited talk at Frascati Workshop
2013 on Multifrequency Behaviour of High Energy Cosmic Sources (Palermo, 27
May - 1 June, 2013). To be published in the International Journal Acta
Polytechnica (CTU
Suzaku Observations of the Supernova Remnant N23 in the Large Magellanic Cloud
X-ray emission from the supernova remnant N23 in the Large Magellanic Cloud
(LMC) is studied using the X-ray Imaging Spectrometer (XIS) onboard Suzaku.
Thanks to superior energy resolution of the XIS in the soft X-ray band, we
resolved H-like and He-like Oxygen K\alpha emission lines from N23 with
unprecedentedly high quality, and as a result, identified a new optically thin
thermal emission component with a temperature ~0.2 keV, as well as that with a
temperature of ~0.5-0.7 keV previously known. This alters the estimate of the
ionization timescale net from ~10^{10-11} cm^-3s to >~10^{12} cm^{-3}s. Under
the assumption that N23 is still in the Sedov phase, its age evaluated from the
newly discovered low temperature component is ~8000 yr, although it is possible
that N23 has already moved into the radiative phase. The abundances of the
heavy elements are found to be roughly consistent with those of the LMC
average, which indicates that the origin of the X-ray emission of N23 is
swept-up ambient material, as expected from its ionization timescale.Comment: 7 pages, 5 figures, accepted for publication in PAS
Deep X-Ray Observations of Supernova Remnants G359.1-0.5 and G359.0-0.9 with ASCA
We present the results of deep ASCA observations of two shell-like radio
supernova remnants (SNRs) located in the direction to the Galactic center (GC)
region. Unlike the radio morphology, G359.1-0.5 shows center-filled X-rays with
prominent K-alpha lines of He-like silicon and H-like sulfur. The plasma
requires at least two temperature components: a silicon-dominated cool plasma
of 0.6keV temperature and a sulfur-dominated higher temperature plasma of
4.4keV. Because the absorption column is ~ 6x10^22 H cm^-2, this SNR would be
near to the GC. The spherical plasma is attributable to supernova ejecta with
the total mass of Si and S being about 0.1 solar mass and 0.3 solar mass,
respectively. X-rays from G359.0-0.9 trace the partial shell structure of the
radio emission. The spectrum is well fitted to a single-temperature plasma of
0.4keV with a non-solar abundance of magnesium or iron. Because the absorption
column is not very large, ~ 1.8x10^22 H cm^-2, G359.0-0.9 would be in front of
the GC region. The total supernova energy, interstellar density near to the
X-ray emitting shell and age of the SNR are estimated to be 1.2x10^51erg,
0.5cm^-3, and 1.8x10^4yr, respectively. We also discuss possible implications
on the origin of the large-scale hot plasma surrounding the GC.Comment: 8 pages, 7 postscript figures, uses PASJ95.sty and PASJadd.sty;
accepted for publication in PASJ 52 April 2000; changed one of figure
Chandra Observations of a Non-Thermal Supernova Remnant Candidate AX J1843.8-0352 and its Surroundings
We present the Chandra results of AX J1843.8-0352, a supernova remnant (SNR)
recently identified with ASCA. Chandra spatially resolved two components from
this SNR: non-thermal and thermal ones. The morphology of the non-thermal
component is clumpy and elliptical, elongated from the north to the south with
a mean diameter of about 9 arcmin. The spectrum is fitted with a power-law
model of photon index 2.1 and the east rim is associated with the non-thermal
radio sources C and F (Helfand et al. 1989). Therefore the non-thermal
component is probably synchrotron X-rays by energetic electrons accelerated at
the shell of the SNR. The thermal component is the brightest clump located
within the non-thermal component and shows a spectrum of a thin plasma of about
0.7 keV temperature. Notable discovery is its peculiar morphology; a head of 50
arcsec x 30 arcsec size near the south-east rim of the SNR and a 30 arcsec-long
``jet'' pointing to the southwest. Although this emission is associated with
the west part of the radio source F, the absorption is twice larger than that
of the non-thermal X-rays, or the bulk of the SNR emission. Therefore, it is
unclear whether this peculiar plasma is a thermal component associated with AX
J1843.8-0352, a Galactic source located in the far side of our Galaxy, or an
extragalactic source.Comment: 19 pages, 5 figures; to appear in Ap
The many sides of RCW 86: a type Ia supernova remnant evolving in its progenitor's wind bubble
We present the results of a detailed investigation of the Galactic supernova
remnant RCW 86 using the XMM-Newton X-ray telescope. RCW 86 is the probable
remnant of SN 185 A.D, a supernova that likely exploded inside a wind-blown
cavity. We use the XMM-Newton Reflection Grating Spectrometer (RGS) to derive
precise temperatures and ionization ages of the plasma, which are an indication
of the interaction history of the remnant with the presumed cavity. We find
that the spectra are well fitted by two non-equilibrium ionization models,
which enables us to constrain the properties of the ejecta and interstellar
matter plasma. Furthermore, we performed a principal component analysis on EPIC
MOS and pn data to find regions with particular spectral properties. We present
evidence that the shocked ejecta, emitting Fe-K and Si line emission, are
confined to a shell of approximately 2 pc width with an oblate spheroidal
morphology. Using detailed hydrodynamical simulations, we show that general
dynamical and emission properties at different portions of the remnant can be
well-reproduced by a type Ia supernova that exploded in a non-spherically
symmetric wind-blown cavity. We also show that this cavity can be created using
general wind properties for a single degenerate system. Our data and
simulations provide further evidence that RCW 86 is indeed the remnant of SN
185, and is the likely result of a type Ia explosion of single degenerate
origin.Comment: Accepted for publication in MNRAS. 16 pages, 13 figure
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