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Posts: 131433
Date:
G350.1-0.3
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G350.1-0.3: Remnant of an Explosion With a Powerful Kick?

g350_w1.jpg

Vital clues about the devastating ends to the lives of massive stars can be found by studying the aftermath of their explosions. In its more than twelve years of science operations, NASA's Chandra X-ray Observatory has studied many of these supernova remnants sprinkled across the Galaxy.
The latest example of this important investigation is Chandra's new image of the supernova remnant known as G350.1+0.3. This stellar debris field is located some 14,700 light years from the Earth toward the center of the Milky Way.

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Posts: 131433
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Supernova remnant
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Title: AGILE observations of Supernova Remnants
Authors: Andrea Giuliani, Martina Cardillo, Marco Tavani, for the AGILE collaboration

We will review the crucial AGILE gamma-ray SNR observations focusing on the evidence of hadronic cosmic-ray acceleration that has been obtained so far. We discuss data on SNR IC443, W28 and W44. We show that in all cases a consistent model of hadronic acceleration and interaction with gaseous surroundings can be used to successfully explain the quite complex morphology and spectral characteristics of the sources. AGILE, with its crucially important sensitivity near 100 MeV, is equipped to prove the existence of pi-zero emission.

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Posts: 131433
Date:
SNR G350.1-0.3
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Title: A Chandra Observation of Supernova Remnant G350.1-0.3 and Its Central Compact Object
Authors: Igor Lovchinsky, Patrick Slane, Bryan Gaensler, John Patrick Hughes, C.-Y. Ng, Jasmina Lazendic-Galloway, Joseph Gelfand, Crystal Brogan

We present a new Chandra observation of supernova remnant (SNR) G350.1-0.3. The high resolution X-ray data reveal previously unresolved filamentary structures and allow us to perform detailed spectroscopy in the diffuse regions of this SNR. Spectral analysis demonstrates that the region of brightest emission is dominated by hot, metal-rich ejecta while the ambient material along the perimeter of the ejecta region and throughout the remnant's western half is mostly low-temperature, shocked interstellar/circumstellar medium (ISM/CSM) with solar-type composition. The data reveal that the emission extends far to the west of the ejecta region and imply a lower limit of 6.6 pc on the diameter of the source (at a distance of 4.5 kpc). We show that G350.1-0.3 is likely in the free expansion (ejecta-dominated) stage and calculate an age of 600-1200 years. The derived relationship between the shock velocity and the electron/proton temperature ratio is found to be entirely consistent with that of other SNRs. We perform spectral fits on the X-ray source XMMU J172054.5-372652, a candidate central compact object (CCO), and find that its spectral properties fall within the typical range of other CCOs. We also present archival 24 um data of G350.1-0.3 taken with the Spitzer Space Telescope during the MIPSGAL galactic survey and find that the infrared and X-ray morphologies are well-correlated. These results help to explain this remnant's peculiar asymmetries and shed new light on its dynamics and evolution.

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Posts: 131433
Date:
G54.1+0.3
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A new image from NASA's Chandra and Spitzer space telescopes shows the dusty remains of a collapsed star. The dust is flying past and engulfing a nearby family of stars.
It shows the Chandra X-ray Observatory data in blue, and data from the Spitzer Space Telescope in green (shorter wavelength) and red-yellow (longer). The white source near the centre of the image is a dense, rapidly rotating neutron star, or pulsar, left behind after a core-collapse supernova explosion. The pulsar generates a wind of high-energy particles -- seen in the Chandra data -- that expands into the surrounding environment, illuminating the material ejected in the supernova explosion.

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Posts: 131433
Date:
Supernova Remnants
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Title: 3D simulations of supernova remnants evolution including non-linear particle acceleration
Authors: Gilles Ferrand (SAp, AIME), Anne Decourchelle (SAp, AIME), Jean Ballet (SAp, AIME), Romain Teyssier (SAp, AIME), Federico Fraschetti (LUTH)

If a sizeable fraction of the energy of supernova remnant shocks is channelled into energetic particles (commonly identified with Galactic cosmic rays), then the morphological evolution of the remnants must be distinctly modified. Evidence of such modifications has been recently obtained with the Chandra and XMM-Newton X-ray satellites. To investigate these effects, we coupled a semi-analytical kinetic model of shock acceleration with a 3D hydrodynamic code (by means of an effective adiabatic index). This enables us to study the time-dependent compression of the region between the forward and reverse shocks due to the back reaction of accelerated particles, concomitantly with the development of the Rayleigh-Taylor hydrodynamic instability at the contact discontinuity. Density profiles depend critically on the injection level eta of particles: for eta up to about 10^-4 modifications are weak and progressive, for eta of the order of 10^-3 modifications are strong and immediate. Nevertheless, the extension of the Rayleigh-Taylor unstable region does not depend on the injection rate. A first comparison of our simulations with observations of Tycho's remnant strengthens the case for efficient acceleration of protons at the forward shock.

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Posts: 131433
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RE: Supernova remnant
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At a very early age, children learn how to classify objects according to their shape. Now, new research suggests studying the shape of the aftermath of supernovas may allow astronomers to do the same.
A new study of images from NASA's Chandra X-ray Observatory on supernova remnants--the debris from exploded stars--shows that the symmetry of the remnants, or lack thereof, reveals how the star exploded. This is an important discovery because it shows that the remnants retain information about how the star exploded, even though hundreds or thousands of years have passed.

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Posts: 131433
Date:
Supernova Remnants
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Title: Distances to Two Galactic Supernova Remnants: G32.8-0.1 and G346.6-0.2
Authors: Jian-Wen Xu, Hui-Rong Zhang

There are either a near kinematic distance of 5.5 kpc or a far distance of 8.8 kpc for a Galactic supernova remnant (SNR) G32.8-0.1 derived by using the rotation curve of the Galaxy. Here we make sure that the remnant distance is the farther one 8.8 kpc through solving a group of equations for the shell-type remnants separately at the adiabatic-phase and the radiative-phase. For SNR G346.6-0.2 we determine its distance also the farther one 11 kpc rather than the nearer one 5.5 kpc.

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Posts: 131433
Date:
RE: Supernova remnant
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Researchers looked at the remnant of a star that exploded in AD 185, as recorded by Chinese astronomers. The remnant, called RCW 86, is located about 8200 light-years away towards the constellation of Circinus (the Drawing Compass). It is probably the oldest record of the explosion of a star.
Using ESOs Very Large Telescope, the team measured the temperature of the gas right behind the shock wave created by the stellar explosion. They measured the speed of the shock wave as well, using images taken with NASAs X-ray Observatory Chandra three years apart. They found it to be moving at between 10 and 30 million km/h, between 1 and 3 percent the speed of light. The temperature of the gas turned out to be 30 million degrees Celsius. This is quite hot compared to everyday standards, but much lower than expected, given the measured shock waves velocity. This should have heated the gas up to at least half a billion degrees.


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Posts: 131433
Date:
SNR RX J1713.7-3946
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Title: A joint spectro-imaging analysis of the XMM-Newton and HESS observations of the supernova remnant RX J1713.7-3946
Authors: F. Acero, J. Ballet, A. Decourchelle, M. Lemoine-Goumard, M. Ortega, E. Giacani, G. Dubner, G. Cassam-Chenai

The supernova remnant (SNR) RX J1713.7-3946 (also known as G347.3-0.5) is part of the class of remnants dominated by synchrotron emission in X-rays. It is also one of the few shell-type SNRs observed at TeV energies allowing to investigate particle acceleration at SNRs shock.
Our goal is to compare spatial and spectral properties of the remnant in X- and gamma-rays to understand the nature of the TeV emission. This requires to study the remnant at the same spatial scale at both energies. To complement the non-thermal spectrum of the remnant, we attempt to provide a reliable estimate for the radio flux density. In radio, we revisited ATCA data and used HI and mid-infrared observations to disentangle the thermal from the non-thermal emission. In X-rays, we produced a new mosaic of the remnant and degraded the spatial resolution of the X-ray data to the resolution of the HESS instrument to perform spatially resolved spectroscopy at the same spatial scale in X- and gamma-rays. Radial profiles were obtained to investigate the extension of the emission at both energies.
We found that part of the radio emission within the SNR contours is thermal in nature. Taking this into account, we provide new lower and upper limits for the integrated synchrotron flux of the remnant at 1.4 GHz of 22 Jy and 26 Jy respectively. In X-rays, we obtained the first full coverage of RX J1713.7-3946 with XMM-Newton. The spatial variation of the photon index seen at small scale in X-rays is smeared out at HESS resolution. A non-linear correlation between the X- and gamma-ray fluxes of the type Fx \propto Fg^2.41 is found.

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Posts: 131433
Date:
RCW86
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Title: Suzaku Observation of the RCW86 Northeastern Shell
Authors: Hiroya Yamaguchi, Katsuji Koyama, Hiroshi Nakajima, Aya Bamba, Ryo Yamazaki, Jacco Vink, Akiko Kawachi
(Version v2)

This paper reports the Suzaku results on the northeast shell of RCW 86. With the spatial and spectral analysis, we separated the X-rays into three distinct components; low (kT_e~0.3keV) and high (kT_e~1.8keV) temperature plasmas and a non-thermal component, and discovered their spatial distributions are different from each other. The low temperature plasma is dominated at the east rim, whereas the non-thermal emission is the brightest at the northeast rim which is spatially connected from the east rim. The high temperature plasma, found to contain the ~6.42keV line (K alpha of low-ionized iron), is enhanced at the inward region with respect to the east rim and has no spatial correlation with the non-thermal X-ray (the northeast). The Fe-Kalpha line, therefore, is not related to the non-thermal emission but originates from Fe-rich ejecta heated to the high temperatures by the reverse shock. Since the metal abundances of the low temperature plasma are sub-solar, the most possible origin of this component is interstellar medium heated by a blast wave. The non-thermal X-ray, which has a power-law index of ~2.8, is likely to be synchrotron emission. A possible scenario to explain these morphologies and spectra is: A fast moving blast wave in a thin cavity of OB association collided with a dense interstellar medium or cloud at the east region very recently. As the result, the reverse shock in this interior decelerated, and arrived at the Fe-rich region of the ejecta and heated it. In the northeast rim, on the other hand, the blast wave is still moving fast, and accelerated high energy electrons to emit synchrotron X-rays.

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