Near-infrared Extinction due to Cool Supernova Dust in Cassiopeia A

Abstract

We present the results of extinction measurements toward the main ejecta shell of the Cassiopeia A supernova (SN) remnant using the flux ratios between the two near-infrared (NIR) [Fe II] lines at 1.26 and 1.64 $\mu \mathrm{m}$. We find a clear correlation between the NIR extinction ($E(J-H)$) and the radial velocity of ejecta knots, showing that redshifted knots are systematically more obscured than blueshifted ones. This internal "self-extinction" strongly indicates that a large amount of SN dust resides inside and around the main ejecta shell. At one location in the southern part of the shell, we measure $E(J-H)$ by the SN dust of 0.23$\pm$0.05 mag. By analyzing the spectral energy distribution of thermal dust emission at that location, we show that there are warm ($\sim$100 K) and cool ($\sim$40 K) SN dust components and that the latter is responsible for the observed $E(J-H)$. We investigate the possible grain species and size of each component and find that the warm SN dust needs to be silicate grains such as MgSiO${}_3$, Mg${}_2$SiO${}_4$, and SiO${}_2$, whereas the cool dust could be either small ($\le$0.01 $\mu \mathrm{m}$) Fe or large ($\ge$0.1 $\mu \mathrm{m}$) Si grains. We suggest that the warm and cool dust components in Cassiopeia A represent grain species produced in diffuse SN ejecta and in dense ejecta clumps, respectively.

34 pages, 9 figures; accepted in ApJ on 2015 June 16

References in corpus (16)

• Dust Formation and Survival in Supernova Ejecta
• The Cassiopeia A Supernova was of Type IIB
• The Expansion Asymmetry and Age of the Cassiopeia A Supernova Remnant
• Freshly Formed Dust in the Cassiopeia A Supernova Remnant as Revealed by the Spitzer Space Telescope
• Spectral Mapping Reconstruction of Extended Sources
• Dust and the type II-plateau supernova 2004et
• A Spitzer Space Telescope Study of SN 2003gd: Still No Direct Evidence that Core-Collapse Supernovae are Major Dust Factories
• The dust and gas content of the Crab Nebula
• Cassiopeia A: dust factory revealed via submillimetre polarimetry
• The Bubble-like Interior of the Core-Collapse Supernova Remnant Cassiopeia A
• No cold dust within the supernova remnant Cassiopeia A
• Early Formation of Dust in the Ejecta of Type Ib SN 2006jc and Temperature and Mass of the Dust
• Interstellar and Ejecta Dust in the Cas A Supernova Remnant
• Spitzer IRAC Images and Sample Spectra of Cassiopeia A's Explosion
• Properties of newly formed dust by SN2006jc based on near-to-mid infrared observation with AKARI
• Empirical determination of Einstein A-coefficient ratios of bright [Fe II] lines

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• Probing the Physical Conditions of Supernova Ejecta with the Measured Sizes of Presolar Al2O3 Grains
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