SPITZER SPECTRAL MAPPING OF SUPERNOVA REMNANT CASSIOPEIA A
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Smith-2009-SPITZER SPECTRAL MAP.pdf
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Author(s)
Smith, J. D. T.
Rudnick, Lawrence
Delaney, Tracey
Rho, Jeonghee
Gomez, Haley
Kozasa, Takashi
Reach, William
Isensee, Karl
DeLaney, Tracey
Date Issued
March 2009
Journal
Astrophysical Journal
Publisher
Institute of Physics/American Astronomical Society
Citation
Smith, J. D. T., Lawrence Rudnick, Tracey Delaney, Jeonghee Rho, Haley Gomez, Takashi Kozasa, William Reach, and Karl Isensee. “ SPITZER SPECTRAL MAPPING OF SUPERNOVA REMNANT CASSIOPEIA A .” The Astrophysical Journal 693, no. 1 (March 1, 2009): 713–721. © 2009 American Astronomical Society.
Version
Final published version
Abstract
We present the global distribution of fine-structure infrared line emission in the Cassiopeia A supernova remnant using data from the Spitzer Space Telescope's infrared spectrograph. We identify emission from ejecta materials in the interior, prior to their encounter with the reverse shock, as well as from the postshock bright ring. The global electron density increases by gsim 100 at the shock to ~10[superscript 4] cm[superscript –3], providing evidence for strong radiative cooling. There is also a dramatic change in ionization state at the shock, with the fading of emission from low-ionization interior species like [Si II] giving way to [S IV] and, at even further distances, high-energy X-rays from hydrogenic silicon. Two compact, crescent-shaped clumps with highly enhanced neon abundance are arranged symmetrically around the central neutron star. These neon crescents are very closely aligned with the "kick" direction of the compact object from the remnant's expansion center, tracing a new axis of explosion asymmetry. They indicate that much of the apparent macroscopic elemental mixing may arise from different compositional layers of ejecta now passing through the reverse shock along different directions.
MIT Department
MIT Kavli Institute for Astrophysics and Space Research
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DOI of Published Version
https://doi.org/10.1088/0004-637x/693/1/713
