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Post Info TOPIC: SN1006
Blobrana


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Posts: 131433
Date:
G327.6+14.6
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Title: Supernova of 1006 (G327.6+14.6)
Author: Satoru Katsuda

SN 1006 (G327.6+14.6) was the brightest supernova (SN) witnessed in human history. As of one thousand years later, it stands out as an ideal laboratory to study Type Ia SNe and shocks in supernova remnants (SNRs). The present state of knowledge about SN 1006 is reviewed in this article. No star consistent with a surviving companion expected in the traditional single-degenerate scenario has been found, which favours a double-degenerate scenario for the progenitor of SN 1006. Both unshocked and shocked SN ejecta have been probed through absorption lines in ultraviolet spectra of background sources and thermal X-ray emission, respectively. The absorption studies suggest that the amount of iron is < 0.16 M_sun, which is significantly less than the range for normal SNe Ia. On the other hand, analyses of X-ray data reveal the distribution of shocked ejecta to be highly asymmetric especially for iron. Therefore, most of iron might have escaped from the ultraviolet background sources. Another important aspect with SN 1006 is that it was the first SNR in which synchrotron X-ray emission was detected from shells of the remnant, providing evidence that electrons are accelerated up to ~100 TeV energies at forward shocks. The bilateral symmetry of the synchrotron emission (bright in northeastern and southwestern limbs) is likely due to a polar cap geometry. The broadband (radio, X-ray, and gamma-ray) spectral energy distribution suggests that the gamma-ray emission is predominantly leptonic. At the northwestern shock, evidence for extreme, but less than mass proportional, temperature non-equilibration has been found by optical, ultraviolet, and X-ray observations.

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Blobrana


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Posts: 131433
Date:
Supernova 1006
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Title: Supernova SN 1006 in two historic Yemeni reports
Author: Wafiq Rada (Hilla University College, Babylon, Iraq), Ralph Neuhaeuser (U Jena)

We present two Arabic texts of historic observations of supernova SN 1006 from Yemen as reported by al-Yamani and Ibn al-Dayba (14th to 16th century AD). An English translation of the report by the latter was given before (Stephenson & Green 2002), but the original Arabic text was not yet published. In addition, we present for the first time the earlier report, also from Yemen, namely by al-Yamani in its original Arabic and with our English translation. It is quite obvious that the report by Ibn al-Dayba is based on the report by al-Yamani (or a common source), but the earlier report by al-Yamani is more detailed and in better (Arabic) language. We discuss in detail the dating of these observations. The most striking difference to other reports about SN 1006 is the apparent early discovery in Yemen in the evening of 15th of Rajab of the year 396h (i.e. AD 1006 Apr 17 ± 2 on the Julian calendar), as reported by both al-Yamani and Ibn al-Dayba. i.e. about 1.5 weeks earlier than the otherwise earliest known reports. We also briefly discuss other information from the Yemeni reports on brightness, light curve, duration of visibility, location, stationarity, and colour.

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Blobrana


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Title: An Integral View of Fast Shocks around Supernova 1006 
Author: Sladjana Nikolic, Glenn van de Ven, Kevin Heng, Daniel Kupko, Bernd Husemann, John C. Raymond, John P. Hughes, Jesús Falcón-Barroso 
Version v2 

Supernova remnants are among the most spectacular examples of astrophysical pistons in our cosmic neighbourhood. The gas expelled by the supernova explosion is launched with velocities ~ 1000 km/s into the ambient, tenuous interstellar medium, producing shocks that excite hydrogen lines. We have used an optical integral-field spectrograph to obtain high-resolution spatial-spectral maps that allow us to study in detail the shocks in the northwestern rim of supernova 1006. The two-component H\alpha\ line is detected at 133 sky locations. Variations in the broad line widths and the broad-to-narrow line intensity ratios across tens of atomic mean free paths suggest the presence of suprathermal protons, the potential seed particles for generating high-energy cosmic-rays. 

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Blobrana


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Posts: 131433
Date:
RE: SN1006
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SN 1006: X-Ray View of A Thousand-Year-Old Cosmic Tapestry

sn1006_525.jpg

When the object we now call SN 1006 first appeared on May 1, 1006 A.D., it was far brighter than Venus and visible during the daytime for weeks. Astronomers in China, Japan, Europe, and the Arab world all documented this spectacular sight.
A new image of SN 1006 from NASA's Chandra X-ray Observatory reveals this supernova remnant in exquisite detail. By overlapping ten different pointings of Chandra's field-of-view, astronomers have stitched together a cosmic tapestry of the debris field that was created when a white dwarf star exploded, sending its material hurtling into space. In this new Chandra image, low, medium, and higher-energy X-rays are coloured red, green, and blue respectively.
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Blobrana


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Posts: 131433
Date:
Supernova 1006
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Title: An Integral View of Fast Shocks around Supernova 1006
Authors: Sladjana Nikoli, Glenn van de Ven, Kevin Heng, Daniel Kupko, Bernd Husemann, John C. Raymond, John P. Hughes, Jesús Falcón-Barroso

Supernova remnants are among the most spectacular examples of astrophysical pistons in our cosmic neighborhood. The gas expelled by the supernova explosion is launched with velocities ~ 1000 km/s into the ambient, tenuous interstellar medium, producing shocks that excite hydrogen lines. We have used an optical integral-field spectrograph to obtain high-resolution spatial-spectral maps that allow us to study in detail the shocks in the northwestern rim of supernova 1006. The two-component H\alpha\ line is detected at 133 sky locations. Variations in the broad line widths and the broad-to-narrow line intensity ratios across tens of atomic mean free paths suggest the presence of suprathermal protons, the potential seed particles for generating high-energy cosmic-rays.

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Blobrana


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Posts: 131433
Date:
RE: SN1006
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Title: The northwestern ejecta knot in SN 1006
Authors: Sjors Broersen, Jacco Vink, Marco Miceli, Fabrizio Bocchino, Gilles Maurin, Anne Decourchelle

Aims: We want to probe the physics of fast collision-less shocks in supernova remnants. In particular, we are interested in the non-equilibration of temperatures and particle acceleration. Specifically, we aim to measure the oxygen temperature with regards to the electron temperature. In addition, we search for synchrotron emission in the northwestern thermal rim.
Methods: This study is part of a dedicated deep observational project of SN 1006 using XMM-Newton, which provides us with currently the best resolution spectra of the bright northwestern oxygen knot. We aim to use the reflection grating spectrometer to measure the thermal broadening of the O vii line triplet by convolving the emission profile of the remnant with the response matrix.
Results: The line broadening was measured to be {\sigma}_e = 2.4 ± 0.3 eV, corresponding to an oxygen temperature of 275^{+72}_{-63} keV. From the EPIC spectra we obtain an electron temperature of 1.19 ± 0.01 keV. The difference in temperature between the species provides further evidence of non-equilibration of temperatures in a shock. In addition, we find evidence for a bow shock that emits X-ray synchrotron radiation, which is at odds with the general idea that due to the magnetic field orientation only in the NE and SW region X-ray synchrotron radiation should be emitted. We find an unusual H{\alpha} and X-ray synchrotron geometry, in that the H{\alpha} emission peaks downstream of the synchrotron emission. This may be an indication for a peculiar H{\alpha} shock, in which the density is lower and neutral fraction are higher than in other supernova remnants, resulting in a peak in H{\alpha} emission further downstream of the shock.

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Blobrana


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Title: No surviving evolved companions to the progenitor of supernova SN 1006
Authors: Jonay I. Gonzalez Hernandez, Pilar Ruiz-Lapuente, Hugo M. Tabernero, David Montes, Ramon Canal, Javier Mendez, Luigi R. Bedin

Type Ia supernovae are thought to occur as a white dwarf made of carbon and oxygen accretes sufficient mass to trigger a thermonuclear explosion. The accretion could occur slowly from an unevolved (main-sequence) or evolved (subgiant or giant) star, that being dubbed the single-degenerate channel, or rapidly as it breaks up a smaller orbiting white dwarf (the double- degenerate channel). Obviously, a companion will survive the explosion only in the single-degenerate channel. Both channels might contribute to the production of type Ia supernovae but their relative proportions still remain a fundamental puzzle in astronomy. Previous searches for remnant companions have revealed one possible case for SN 1572, though that has been criticised. More recently, observations have restricted surviving companions to be small, main-sequence stars, ruling out giant companions, though still allowing the single-degenerate channel. Here we report the result of a search for surviving companions to the progenitor of SN 1006. None of the stars within 4' of the apparent site of the explosion is associated with the supernova remnant, so we can firmly exclude all giant and subgiant companions to the progenitor. Combined with the previous results, less than 20 per cent of type Ia occur through the single degenerate channel.

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Blobrana


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Posts: 131433
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Mystery Behind Supernova SN 1006 Solved?

The Egyptian/Arabic physician and astronomer Ali ibn Ridwan noted that "the sky was shining" from the light of SN 1006, adding, "the intensity of its light was a little more than a quarter than of moon light." He also compared its brightness as being three times greater than Venus.
Frank Winkler, an astronomer at Middlebury College, was able to ascertain just what ibn Ridwan described by using basic mathematics to precisely estimate the brightness of SN 1006. Since Winkler knew it was a Type 1a, he also knew its luminosity, since all such supernovae produce the same amount of light.
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Blobrana


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Posts: 131433
Date:
SN 1006
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Title: XMM-Newton evidence of shocked ISM in SN 1006: indications of hadronic acceleration
Authors: M. Miceli, F. Bocchino, A. Decourchelle, G. Maurin, J. Vink, S. Orlando, F. Reale, S. Broersen

Shock fronts in young supernova remnants are the best candidates for being sites of cosmic ray acceleration up to a few PeV, though conclusive experimental evidence is still lacking. Hadron acceleration is expected to increase the shock compression ratio, providing higher postshock densities, but X-ray emission from shocked ambient medium has not firmly been detected yet in remnants where particle acceleration is at work. We exploited the deep observations of the XMM-Newton Large Program on SN 1006 to verify this prediction. We performed spatially resolved spectral analysis of a set of regions covering the southeastern rim of SN 1006. We studied the spatial distribution of the thermodynamic properties of the ambient medium and carefully verified the robustness of the result with respect to the analysis method. We detected the contribution of the shocked ambient medium. We also found that the postshock density of the interstellar medium significantly increases in regions where particle acceleration is efficient. Under the assumption of uniform preshock density, we found that the shock compression ratio reaches a value of ~6 in regions near the nonthermal limbs. Our results support the predictions of shock modification theory and indicate that effects of acceleration of cosmic ray hadrons on the postshock plasma can be observed in supernova remnants.

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Blobrana


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Posts: 131433
Date:
Supernova 1006
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Title: Hunting for the progenitor of SN 1006: High resolution spectroscopic search with the FLAMES instrument
Authors: Wolfgang E. Kerzendorf, Brian P. Schmidt, John B. Laird, Philipp Podsiadlowski, Michael S. Bessell

Type Ia supernovae play a significant role in the evolution of the Universe and have a wide range of applications. It is widely believed that these events are the thermonuclear explosions of carbon-oxygen white dwarfs close to the Chandrasekhar mass (1.38 Solar masses). However, CO white dwarfs are born with masses much below the Chandrasekhar limit and thus require mass accretion to become Type Ia supernovae. There are two main scenarios for accretion. First, the merger of two white dwarfs and, second, a stable mass accretion from a companion star. According to predictions, this companion star (also referred to as donor star) survives the explosion and thus should be visible in the center of Type Ia remnants. In this paper we scrutinize the central stars (79 in total) of the SN 1006 remnant to search for the surviving donor star as predicted by this scenario. We find no star consistent with the traditional accretion scenario in SN1006.

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