I present observations of shock-processed PAHs and dust in supernova remnants (SNRs).
Supernova shocks are one of the primary sites destroying, fragmenting and altering
interstellar PAHs and dust. Studies of PAHs through supernova shocks had been limited
because of confusion with PAHs in background emission. Spitzer
observations with high sensitivity and resolution allow us to separate PAHs
associated with the SNRs and unrelated, Galactic PAHs. In the young SNR N132D, PAH
features are detected with a higher PAH ratio of 15–20/7.7 μm than those
of other astronomical objects, and we suggest large PAHs have survived behind the shock.
We present the spectra of additional 14 SNRs observed with Spitzer IRS
and MIPS SED covering the range of 5–90 μm. Bright PAH features from 6.2
to 15–20 μm are detected from many of SNRs which emit molecular hydrogen
lines, indicating that both large and small PAHs survive in low velocity shocks. We
observe a strong correlation between PAH detection and carbonaceous small grains, while a
few SNRs with dominant silicate dust lack PAH features. We characterize PAHs depending on
the shock velocity, preshock density and temperature of hot gas, and discuss PAH and dust
processing in shocks and implication of PAH and dust cycles in ISM.