The Density and Mass of Unshocked Ejecta in Cassiopeia a Through Low Frequency Radio Absorption

DeLaney, Tracey; Kassim, N. E.; Rudnick, Lawrence; Perley, R. A.

doi:10.1088/0004-637x/785/1/7

Cited by 56 publications

(47 citation statements)

References 53 publications

(133 reference statements)

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“…This value is in good agreement with that inferred from the analysis of low-frequency (<100 MHz) radio observations (≈0.39 M e ; DeLaney et al 2014) and that derived by Hwang & Laming (2012) by interpreting the Chandra observations with hydrodynamic models (≈0.30 M e ).…”

Section: Unshocked Ejectasupporting

confidence: 90%

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: Unshocked Ejectasupporting

confidence: 90%

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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“…Although a spectral index of α=-0.644 provides a good fit to the global synchrotron power spectrum in Cas A, local variations in spectral index between different knots have been observed (Anderson & Rudnick 1996;Wright et al 1999;DeLaney et al 2014). The shocked ejecta with the brightest synchrotron emission are mostly consistent with this spectral index derived on global scales, while α variations are observed in some knots outside of the reverse shock (DeLaney et al 2014).…”

Section: Modelling the Synchrotron Componentsupporting

confidence: 51%

The dust mass in Cassiopeia A from a spatially resolvedHerschelanalysis

Looze¹,

Barlow²,

Swinyard³

et al. 2016

Mon. Not. R. Astron. Soc.

152

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Theoretical models predict that core-collapse supernovae (CCSNe) can be efficient dust producers (0.1-1.0 M ), potentially accounting for most of the dust production in the early Universe. Observational evidence for this dust production efficiency is however currently limited to only a few CCSN remnants (e.g., SN 1987A, Crab Nebula). In this paper, we revisit the dust mass produced in Cassiopeia A (Cas A), a ∼330-year old Orich Galactic supernova remnant (SNR) embedded in a dense interstellar foreground and background. We present the first spatially resolved analysis of Cas A based on Spitzer and Herschel infrared and submillimetre data at a common resolution of ∼0.6 for this 5 diameter remnant following a careful removal of contaminating line emission and synchrotron radiation. We fit the dust continuum from 17 to 500 µm with a fourcomponent interstellar medium (ISM) and supernova (SN) dust model. We find a concentration of cold dust in the unshocked ejecta of Cas A and derive a mass of 0.3-0.5 M of silicate grains freshly produced in the SNR, with a lower limit of ≥0.1-0.2 M . For a mixture of 50% of silicate-type grains and 50% of carbonaceous grains, we derive a total SN dust mass between 0.4 M and 0.6 M . These dust mass estimates are higher than from most previous studies of Cas A and support the scenario of supernova dominated dust production at high redshifts. We furthermore derive an interstellar extinction map for the field around Cas A which towards Cas A gives average values of A V = 6-8 mag, up to a maximum of A V = 15 mag.

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“…The SNR also contains ejecta which has not yet encountered the reverse shock, and is consequently much cooler. Smith et al (2009) estimated a maximum electron density of ne 100 cm −3 for the unshocked ejecta based on forbidden line ratios, while observations of radio absorption by DeLaney et al (2014) and Arias et al (2018) give ne ∼ 10 cm −3 and T ∼ 100 K. Raymond et al (2018) inferred a preshock temperature of ∼ 100 K from [Si I] IR emission lines. Krause et al (2008) determined that the Cas A SN was of type IIb from a spectrum of its light echo, meaning that the progenitor star must have lost most of its hydrogen envelope pre-explosion.…”

Section: Physical Properties Of the Cas A Snrmentioning

confidence: 99%

The mass, location, and heating of the dust in the Cassiopeia A supernova remnant

Priestley

Barlow

2019

Monthly Notices of the Royal Astronomical Society

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We model the thermal dust emission from dust grains heated by synchrotron radiation and by particle collisions, under conditions appropriate for four different shocked and unshocked gas components of the Cassiopeia A (Cas A) supernova remnant (SNR). By fitting the resulting spectral energy distributions (SEDs) to the observed SNR dust fluxes, we determine the required mass of dust in each component. We find the observed SED can be reproduced by ∼ 0.6 M ⊙ of silicate grains, the majority of which is in the unshocked ejecta and heated by the synchrotron radiation field. Warmer dust, located in the X-ray emitting reverse shock and blastwave regions, contribute to the shorter wavelength infrared emission but make only a small fraction of the total dust mass. Carbon grains can at most make up ∼ 25% of the total dust mass. Combined with estimates for the gas masses, we obtain dust-to-gas mass ratios for each component, which suggest that the condensation efficiency in the ejecta is high, and that dust in the shocked ejecta clumps is well protected from destruction by sputtering in the reverse shock.

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The Density and Mass of Unshocked Ejecta in Cassiopeia a Through Low Frequency Radio Absorption

Cited by 56 publications

References 53 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

The dust mass in Cassiopeia A from a spatially resolvedHerschelanalysis

The mass, location, and heating of the dust in the Cassiopeia A supernova remnant

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