The dust mass in Cassiopeia A from a spatially resolved Herschel analysis
Abstract
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 0.3-0.5 M⊙ 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 0.6 M⊙. 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 AV = 6-8 mag, up to a maximum of AV = 15 mag.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- March 2017
- DOI:
- 10.1093/mnras/stw2837
- arXiv:
- arXiv:1611.00774
- Bibcode:
- 2017MNRAS.465.3309D
- Keywords:
-
- supernovae: individual: Cassiopeia A;
- dust;
- extinction;
- ISM: supernova remnants;
- infrared: ISM;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 37 pages, 24 figures, Manuscript published in MNRAS, including minor corrections. Accepted on 01/11/2016. Deposited on 08/01/2017