English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We present results from mid-IR spectroscopic observations of two youngsupernova remnants (SNRs) in the Large Magellanic Cloud (LMC) done with the{\it Spitzer Space Telescope}. We imaged SNRs B0509-67.5 and B0519-69.0 with{\it Spitzer} in 2005, and follow-up spectroscopy presented here confirms thepresence of warm, shock heated dust, with no lines present in the spectrum. Weuse model fits to {\it Spitzer} IRS data to estimate the density of thepostshock gas. Both remnants show asymmetries in the infrared images, and weinterpret bright spots as places where the forward shock is running intomaterial that is several times denser than elsewhere. The densities we inferfor these objects depend on the grain omposition assumed, and we explore theeffects of differing grain porosity on the model fits. We also analyze archival{\it XMM-Newton} RGS spectroscopic data, where both SNRs show strong lines ofboth Fe and Si, coming from ejecta, as well as strong O lines, which may comefrom ejecta or shocked ambient medium. We use model fits to IRS spectra topredict X-ray O line strengths for various grain models and values of the shockcompression ratio. For 0509-67.5, we find that compact (solid) grain modelsrequire nearly all O lines in X-ray spectra to originate in reverse-shockedejecta. Porous dust grains would lower the strength of ejecta lines relative tothose arising in the shocked ambient medium. In 0519-69.0, we find significantevidence for a higher than standard compression ratio of 12, implying efficientcosmic-ray acceleration by the blast wave. A compact grain model is favoredover porous grain models. We find that the dust-to-gas mass ratio of theambient medium is significantly lower than what is expected in the ISM.

Dusty Blastwaves of Two Young LMC Supernova Remnants: Constraints on Postshock Compression