A dust twin of Cas A: cool dust and 21 μm silicate dust feature in the supernova remnant G54.1+0.3

We present infrared (IR) and submillimetre observations of the Crab-like supernova remnant (SNR) G54.1+0.3 including 350μm (SHARC-II), 870μm (LABOCA), 70, 100, 160, 250, 350, and 500 μm (Herschel), and 3-40 μm (Spitzer). We detect dust features at 9, 11, and 21 μm and a long-wavelength continuum dust component. The 21 μm dust coincides with [Ar II] ejecta emission, and the feature is remarkably similar to that in Cas A. The IRAC 8μm image including Ar ejecta is distributed in a shell-like morphology which is coincident with dust features, suggesting that dust has formed in the ejecta. We create a cold dust map that shows excess emission in the northwestern shell. We fit the spectral energy distribution of the SNR using the continuous distributions of ellipsoidal grain model of pre-solar grain SiO₂ that reproduces the 21 and 9 μm dust features and discuss grains of silicon carbide and polycyclic aromatic hydrocarbon that may be responsible for the 10-13 μm dust features. To reproduce the long-wavelength continuum, we explore models consisting of different grains including Mg₂SiO₄, MgSiO₃, Al₂O₃, FeS, carbon, and Fe₃O₄. We tested a model with a temperature-dependent silicate absorption coefficient. We detect cold dust (27-44 K) in the remnant, making this the fourth such SNR with freshly formed dust. The total dust mass in the SNR ranges from 0.08 to 0.9 M_{⊙} depending on the grain composition, which is comparable to predicted masses from theoretical models. Our estimated dust masses are consistent with the idea that SNe are a significant source of dust in the early Universe.