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

Abstract

We present results from mid-IR spectroscopic observations of two young supernova 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 the presence of warm, shock heated dust, with no lines present in the spectrum. We use model fits to {\it Spitzer} IRS data to estimate the density of the postshock gas. Both remnants show asymmetries in the infrared images, and we interpret bright spots as places where the forward shock is running into material that is several times denser than elsewhere. The densities we infer for these objects depend on the grain omposition assumed, and we explore the effects of differing grain porosity on the model fits. We also analyze archival {\it XMM-Newton} RGS spectroscopic data, where both SNRs show strong lines of both Fe and Si, coming from ejecta, as well as strong O lines, which may come from ejecta or shocked ambient medium. We use model fits to IRS spectra to predict X-ray O line strengths for various grain models and values of the shock compression ratio. For 0509-67.5, we find that compact (solid) grain models require nearly all O lines in X-ray spectra to originate in reverse-shocked ejecta. Porous dust grains would lower the strength of ejecta lines relative to those arising in the shocked ambient medium. In 0519-69.0, we find significant evidence for a higher than standard compression ratio of 12, implying efficient cosmic-ray acceleration by the blast wave. A compact grain model is favored over porous grain models. We find that the dust-to-gas mass ratio of the ambient medium is significantly lower than what is expected in the ISM.

Accepted for publication in ApJ. 47 pages, 16 figures

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• Infrared and X-Ray Evidence for Circumstellar Grain Destruction by the Blast Wave of Supernova 1987A
• The relation between post-shock temperature, cosmic-ray pressure and cosmic-ray escape for non-relativistic shocks
• Cosmic-Ray Acceleration Efficiency vs Temperature Equilibration: the Case of SNR 0509-67.5
• Distances to Populous Clusters in the LMC via the K-Band Luminosity of the Red Clump
• XMM-Newton X-ray spectra of the SNR 0509-67.5: data and models

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• The Importance of Physical Models for Deriving Dust Masses and Grain Size Distributions in Supernova Ejecta I: Radiatively Heated Dust in the Crab Nebula
• Dust Destruction Rates and Lifetimes in the Magellanic Clouds
• The Progenitor of the Type Ia Supernova that created SNR 0519-69.0 in the Large Magellanic Cloud
• Kepler's Supernova: An Overluminous Type Ia Event Interacting with a Massive Circumstellar Medium at a Very Late Phase
• Dust in a Type Ia Supernova Progenitor: Spitzer Spectroscopy of Kepler's Supernova Remnant
• The Absence of Ex-Companions in Type Ia Supernova Remnants
• A survey of infrared supernova remnants in the Large Magellanic Cloud
• Spitzer Observations of the Type Ia Supernova Remnant N103B: Kepler's Older Cousin?
• Infrared Supernova Remnants and their Infrared to X-ray Flux Ratios
• A Complete Catalogue of Dusty Supernova Remnants
• Collisional and Radiative Processes in Optically Thin Plasmas
• Newly Determined Explosion Center of Tycho's Supernova and the Implications for Proposed Ex-Companion Stars of the Progenitor
• Nonuniform Expansion of the Youngest Galactic Supernova Remnant G1.9+0.3
• Grain Destruction in a Supernova Remnant Shock Wave
• The First Reported Infrared Emission from the SN 1006 Remnant
• Spitzer Imaging and Spectral Mapping of the Oxygen-Rich Supernova Remnant G292.0+1.8
• Dust Cooling in Supernova Remnants in the Large Magellanic Cloud
• RGS Observations of Ejecta Knots in Tycho's Supernova Remnant
• A Hydro-Based MCMC Analysis of SNR 0509-67.5 Revealing the Explosion Properties from Fluid Discontinuities Alone
• The Cold Dust Content of the Oxygen-Rich Supernova Remnant G292.0+1.8
• Infrared Emission from Supernova Remnants: Formation and Destruction of Dust
• Rapid Expansion of the Young Type Ia Supernova Remnant 0519-69.0: More Evidence for a Circumstellar Shell
• An X-ray Proper Motion Study of the LMC SNR 0509-67.5
• Efficiencies of Magnetic-Field Amplification and Electron Acceleration in Young Supernova Remnants: Global Averages and Kepler's Supernova Remnant