The Polar Regions of Cassiopeia A: The Aftermath of a Gamma‐Ray Burst?

Laming, J. M.; Hwang, U.; Radics, B.; Lekli, Gergely; Takács, Endre

doi:10.1086/503553

Cited by 52 publications

(75 citation statements)

References 82 publications

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“…We note that the total kinetic energy of all the pistons is about 1.5×10 50 erg. Thus the pistons/jets represent a relatively small fraction (≈7%) of the remnantʼs energy budget, at odds with previous estimates (e.g., Willingale et al 2003;Laming et al 2006).…”

Section: Spatial Distribution and Chemical Composition Of The Cas A Econtrasting

confidence: 75%

Modeling SNR Cassiopeia a From the Supernova Explosion to Its Current Age: The Role of Post-Explosion Anisotropies of Ejecta

Orlando

Miceli

Pumo

et al. 2016

ApJ

113

138

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The remnants of core-collapse supernovae (SNe) have complex morphologies that may reflect asymmetries and structures developed during the progenitor SN explosion. Here we investigate how the morphology of the supernova remnant Cassiopeia A (Cas A) reflects the characteristics of the progenitor SN with the aim of deriving the energies and masses of the post-explosion anisotropies responsible for the observed spatial distribution of Fe and Si/S. We model the evolution of Cas A from the immediate aftermath of the progenitor SN to the three-dimensional interaction of the remnant with the surrounding medium. The post-explosion structure of the ejecta is described by small-scale clumping of material and larger-scale anisotropies. The hydrodynamic multi-species simulations consider an appropriate post-explosion isotopic composition of the ejecta. The observed average expansion rate and shock velocities can be well reproduced by models with ejecta mass M ej ≈4M e and explosion energy E SN ≈2.3×10 51 erg. The post-explosion anisotropies (pistons) reproduce the observed distributions of Fe and Si/ S if they had a total mass of ≈0.25 M e and a total kinetic energy of ≈1.5×10 50 erg. The pistons produce a spatial inversion of ejecta layers at the epoch of Cas A, leading to the Si/S-rich ejecta physically interior to the Fe-rich ejecta. The pistons are also responsible for the development of the bright rings of Si/S-rich material which form at the intersection between the reverse shock and the material accumulated around the pistons during their propagation. Our result supports the idea that the bulk of asymmetries observed in Cas A are intrinsic to the explosion.

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Section: Spatial Distribution and Chemical Composition Of The Cas A Econtrasting

confidence: 75%

Modeling SNR Cassiopeia a From the Supernova Explosion to Its Current Age: The Role of Post-Explosion Anisotropies of Ejecta

Orlando

Miceli

Pumo

et al. 2016

ApJ

113

138

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“…Using this average value, we estimate a total kinetic energy of the NE/SW bipolar flows of 1 × 10 50 (N knots /3400) (n e /4000 cm −3 ) (f/0.5) erg. Interestingly, this same energy value was estimated by Laming et al (2006) for just the NE jet alone based on hydrodynamical models. Schure et al (2008) derived a lower limit for the jet/counterjet system of ∼ 2 × 10 48 erg also from hydrodynamic modeling.…”

Section: Mass and Energy Of Outer Ejecta Knotssupporting

confidence: 72%

“…However, most researchers now agree that the highvelocity ejecta along the NE-SW limbs of Cas A point to a real and significant asymmetrical expansion of the Cas A supernova (Laming et al 2006;DeLaney et al 2010;Hwang & Laming 2012;Milisavljevic & Fesen 2013). What they disagree on is the importance and relevance of the NE/SW jets to the dynamics of the supernova explosion engine.…”

Section: The Nature Of the Jet/counterjetmentioning

confidence: 99%

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An HST Survey of the Highest-Velocity Ejecta in Cassiopeia A*

Fesen

Milisavljevic

2016

ApJ

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We present Hubble Space Telescope WFC3/IR images of the Cassiopeia A supernova remnant that survey its high-velocity, S-rich debris in the NE jet and SW counterjet regions through [S III] λλ9069, 9531 and [S II] λλ10,287 -10,370 line emissions. We identify nearly 3400 sulfur emitting knots concentrated in ∼120• wide opposing streams, almost triple the number previously known. The vast majority of these ejecta knots lie at projected distances well out ahead of the remnant's forward blast wave and main shell ejecta, extending to angular distance of 320 to the NE and 260 to the SW from the center of expansion. Such angular distances imply undecelerated ejecta knot transverse velocities of 15,600 and 12,700 km s −1 respectively, assuming an explosion date ≈1670 AD and a distance of 3.4 kpc. Optical spectra of knots near the outermost tip of the NE ejecta stream show strong emission lines of S, Ca, and Ar. We estimate a total mass ∼ 0

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“…While the jets do produce a slight bipolar asymmetry in the ejecta, there is no obvious way in which the jets cause most of the ejecta asymmetries described in Section 4. Furthermore, Cas A's jets do not appear to have enough kinetic energy in order to cause the supernova explosion (Laming et al 2006). Wheeler et al (2008) propose that the structures normally called the "jet" and "counterjet" are not the main jets, but rather secondary instabilities.…”

Section: Nature Of the Explosionmentioning

confidence: 99%

The Three-Dimensional Structure of Interior Ejecta in Cassiopeia a at High Spectral Resolution

Isensee

Rudnick

DeLaney

et al. 2010

ApJ

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We used the Spitzer Space Telescope's Infrared Spectrograph to create a high-resolution spectral map of the central region of the Cassiopeia A (Cas A) supernova remnant, allowing us to make a Doppler reconstruction of its threedimensional structure. The ejecta responsible for this emission have not yet encountered the remnant's reverse shock or the circumstellar medium, making it an ideal laboratory for exploring the dynamics of the supernova explosion itself. We observe that the O, Si, and S ejecta can form both sheet-like structures and filaments. Si and O, which come from different nucleosynthetic layers of the star, are observed to be coincident in velocity space in some regions, and separated by 500 km s −1 or more in others. Ejecta traveling toward us are, on average, ∼900 km s −1 slower than the material traveling away from us. We compare our observations to recent supernova explosion models and find that no single model can simultaneously reproduce all the observed features. However, models of different supernova explosions can collectively produce the observed geometries and structures of the interior emission. We use the results from the models to address the conditions during the supernova explosion, concentrating on asymmetries in the shock structure. We also predict that the back surface of Cas A will begin brightening in ∼30 years, and the front surface in ∼100 years.

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The Polar Regions of Cassiopeia A: The Aftermath of a Gamma‐Ray Burst?

Cited by 52 publications

References 82 publications

Modeling SNR Cassiopeia a From the Supernova Explosion to Its Current Age: The Role of Post-Explosion Anisotropies of Ejecta

Modeling SNR Cassiopeia a From the Supernova Explosion to Its Current Age: The Role of Post-Explosion Anisotropies of Ejecta

An HST Survey of the Highest-Velocity Ejecta in Cassiopeia A*

The Three-Dimensional Structure of Interior Ejecta in Cassiopeia a at High Spectral Resolution

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