The dust mass in Cassiopeia A from a spatially resolved Herschel analysis.

Theoretical models predict that core-collapse supernovae (CCSNe) can be efficient dust producers (0.1-1.0 M_☉), potentially accounting for most of the dust production in the early Universe. Observational evidence for this dust production efficiency is however currently limited to only a few CCSN remnants (e.g. SN 1987A, Crab nebula). In this paper, we revisit the dust mass produced in Cassiopeia A (Cas A), a ~330-yr old O-rich Galactic supernova remnant (SNR) embedded in a dense interstellar foreground and background. We present the first spatially resolved analysis of Cas A based on Spitzer and Herschel infrared and submillimetre data at a common resolution of ~0.6 arcmin for this 5 arcmin diameter remnant following a careful removal of contaminating line emission and synchrotron radiation. We fit the dust continuum from 17 to 500 μm with a four-component interstellar medium and supernova (SN) dust model.We find a concentration of cold dust in the unshocked ejecta of Cas A and derive a mass of 0.3-0.5M_☉ of silicate grains freshly produced in the SNR, with a lower limit of ≥0.1- 0.2 M_☉. For a mixture of 50 per cent of silicate-type grains and 50 per cent of carbonaceous grains, we derive a total SN dust mass between 0.4 and 0.6M_☉. These dust mass estimates are higher than from most previous studies of Cas A and support the scenario of SN-dominated dust production at high redshifts. We furthermore derive an interstellar extinction map for the field around Cas A which towards Cas A gives average values of A_V = 6-8 mag, up to a maximum of A_V = 15 mag. [ABSTRACT FROM AUTHOR]