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TOPIC: Puppis A


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Title: The most complete and detailed X-ray view of the SNR Puppis A
Authors: G. Dubner, N. Loiseau, P. Rodriguez-Pascual, M.J.S. Smith, E. Giacani, G. Castelletti

With the purpose of producing the first detailed full view of Puppis A in X-rays, we carried out new XMM-Newton observations covering the missing regions in the southern half of the supernova remnant (SNR) and combined them with existing XMM-Newton and Chandra data. The new images were produced in the 0.3-0.7, 0.7-1.0 and 1.0-8.0 energy bands. We investigated the SNR morphology in detail, carried out a multi-wavelength analysis and estimated the flux density and luminosity of the whole SNR. The complex structure observed across the remnant confirms that Puppis A evolves in an inhomogeneous, probably knotty interstellar medium. The southwestern corner includes filaments that perfectly correlate with radio features suggested to be associated with shock/cloud interaction. In the northern half of Puppis A the comparison with Spitzer infrared images shows an excellent correspondence between X-rays and 24 and 70 microns emission features, while to the south there are some matched and other unmatched features. X-ray flux densities of 12.6 x 10^-9, 6.2 x 10^-9, and 2.8 x 10^-9 erg cm^-2 s^-1 were derived for the 0.3-0.7, 0.7-1.0 and 1.0-8.0 keV bands, respectively. At the assumed distance of 2.2 kpc, the total X-ray luminosity between 0.3 and 8.0 keV is 1.2 x 10^37 erg s^-1. We also collected and updated the broad-band data of Puppis A between radio and GeV gamma-ray range, producing its spectral energy distribution. To provide constraints to the high-energy emission models, we re-analysed radio data, estimating the energy content in accelerated particles to be Umin=4.8 X 10^49 erg and the magnetic field strength B=26 muG.

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Title: Fermi-LAT and WMAP observations of the Puppis A Supernova Remnant
Authors: J.W. Hewitt, M.-H. Grondin, M. Lemoine-Goumard, T. Reposeur, J. Ballet, T. Tanaka

We report the detection of GeV \gamma-ray emission from the supernova remnant Puppis A with the Fermi Gamma-Ray Space Telescope. Puppis A is among the faintest supernova remnants yet detected at GeV energies, with a luminosity of only 2.7x10^34 (D/2.2 kpc)^2 erg/s between 1 and 100 GeV. The \gamma-ray emission from the remnant is spatially extended, with a morphology matching that of the radio and X-ray emission, and is well described by a simple power law with an index of 2.1. We attempt to model the broadband spectral energy distribution, from radio to \gamma-rays, using standard nonthermal emission mechanisms. To constrain the relativistic electron population we use 7 years of WMAP data to extend the radio spectrum up to 93 GHz. Both leptonic and hadronic dominated models can reproduce the nonthermal spectral energy distribution, requiring a total content of cosmic ray (CR) electrons and protons accelerated in Puppis A of at least (1-5)x10^49 erg.

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Star Explosion Leaves Behind a Rose

About 3,700 years ago, people on Earth would have seen a brand-new bright star in the sky. It slowly dimmed out of sight and was eventually forgotten, until modern astronomers later found its remains, called Puppis A. In this new image from NASA's Wide-field Infrared Survey Explorer (WISE), Puppis A looks less like the remains of a supernova explosion and more like a red rose.
Puppis A was formed when a massive star ended its life in a supernova, the most brilliant and powerful form of an explosion in the known universe. The expanding shock waves from that explosion are heating up the dust and gas clouds surrounding the supernova, causing them to glow and appear red in this infrared view. While much of the material from that original star was violently thrown out into space, some of it remained in an incredibly dense object called a neutron star.

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RX J0822-4300
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One of the fastest-moving stars ever discovered in the Milky Way has challenged theories about why its moving so fast.
The object is a piece of the Puppis A supernova remnant created when a massive star ended its life in a supernova explosion about 3,700 years ago, forming an incredibly dense object called a neutron star.
Astronomers used five years of NASAs Chandra X-ray Observatory images to show that the rogue star, poetically dubbed RX J0822-4300, is careening away from whats left of a star that exploded about 3,700 years ago.


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Title: A Fast-Moving Central Compact Object in Puppis-A
Authors: C. Y. Hui, W. Becker

Utilising two Chandra High Resolution Camera (HRC-I) observations with an epoch separation of somewhat more than five years, we have measured the proper motion of the central compact object, RX J0822-4300, in the supernova remnant Puppis-A for the first time. The position of RX J0822-4300 is found to be different by 0.574 0.184 arcsec, implying a proper motion of 107.49 34.46 mas/yr with a position angle of 241 degree 24 degree. For a distance of 2.2 kpc, this proper motion is equivalent to a recoil velocity of 1121.79 359.60 km/s. Both the magnitude and the direction of the proper motion are in agreement with the birth place of RX J0822-4300 being near to the optical expansion centre of the supernova remnant. Although the positional shift inferred from the current data is significant at a ~ 3 sigma level only, one or more future HRC-I observations can obtain a much larger positional separation and further constrain the measurement.

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Puppis-A is one of the brightest supernova remnants in the X-ray sky and has been known as such since the early years of X-ray astronomy. Puppis-A is estimated to be at a distance of ~ 6,500 light years and to be borne in a supernova event about 2,500 years ago.

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Title: Chandra X-ray Observation of a Mature Cloud-Shock Interaction in the Bright Eastern Knot Region of Puppis A
Authors; Una Hwang, Kathryn A. Flanagan, Robert Petre

We present Chandra X-ray images and spectra of the most prominent cloudshock interaction region in the Puppis A supernova remnant. The Bright Eastern Knot (BEK) has two main morphological components: (1) a bright compact knot that lies directly behind the apex of an indentation in the eastern X-ray boundary and (2) lying 1' westward behind the shock, a curved vertical structure (bar) that is separated from a smaller bright cloud (cap) by faint diffuse emission.
Based on hardness images and spectra, we identify the bar and cap as a single shocked interstellar cloud. Its morphology strongly resembles the "voided sphere" structures seen at late times in Klein et al.s experimental simulations of cloud-shock interactions, when the crushing of the cloud by shear instabilities is well underway.
We infer an interaction time of roughly 3 cloud-crushing timescales, which translates to 2000-4000 years, based on the X-ray temperature, physical size, and estimated expansion of the shocked cloud. This is the first X-ray identified example of a cloud-shock interaction in this advanced phase. Closer to the shock front, the X-ray emission of the compact knot in the eastern part of the BEK region implies a recent interaction with relatively denser gas, some of which lies in front of the remnant. The complex spatial relationship of the X-ray emission of the compact knot to optical [O III] emission suggests that there are multiple cloud interactions occurring along the line of sight.

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This Chandra Xray telescope three-colour image of a region of the supernova remnant Puppis A (wide-angle view from ROSAT in blue) reveals a cloud being torn apart by a shock wave produced in a supernova explosion.
This is the first X-ray identification of such a process in an advanced phase. In the inset, the blue vertical bar and the blue fuzzy ball or cap to the right show how the cloud has been spread out into an oval-shaped structure that is almost empty in the centre. The Chandra data also provides information on the temperature in and around the cloud, with blue representing higher temperature gas.


Position (2000): RA = 08h 23m 08.16s Dec = -42 41' 41.40
ROSAT image is 88 arcmin across; Chandra image is 8 arcmin across


The oval structure strongly resembles those seen on much smaller size scales in experimental simulations of the interaction of supernova shock waves with dense interstellar clouds that lie 7,000 light years away in the southern constellation of Puppis (The Stern). In these experiments, a strong shock wave sweeps over a vaporized copper ball that has a diameter roughly equal to a human hair. The cloud is compressed, and then expands in about 40 nanoseconds to form an oval bar and cap structure much like that seen in Puppis A.

On a cosmic scale, the disruption of l0-light-year-diameter cloud in Puppis A took a few thousand years. Despite the vast difference in scale, the experimental structures and those observed by Chandra are remarkably similar. The similarity gives astrophysicists insight into the interaction of supernova shock waves with interstellar clouds.

Understanding this process is important for answering key questions such as the role supernovas play in heating interstellar gas and triggering the collapse of large interstellar clouds to form new generations of stars.

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