Dust polarisation properties in the Crab Nebula
- Principal Investigator
- Ilse De Looze
- Proposal ID
- 06_0193
- Category
- ISM_AND_CIRCUMSTELLAR_MATTER
- Keywords
- CHEMICAL ABUNDANCES
- DUST
- SUPERNOVA REMNANTS
Abstract
The large reservoirs of dust observed in some high redshift galaxies are difficult to explain without core-collapse supernovae (CCSNe) as a dominant dust production source. Theoretical studies tend to support efficient dust condensation in CCSNe, but the number of CCSNe with robust detections of >0.1 Msun of dust remains scarse (SN1987A, Cas A, Crab Nebula). Our lack of knowledge on the composition of freshly produced grains make supernova dust masses uncertain by factors of a few. The average size of supernova dust will furthermore strongly affect the fraction of grains that will survive supernova shocks before mixing with pre-existing interstellar dust. Larger grains would be less susceptible to shock processing, but the absence of constraints on the average supernova grain size make it impossible to anticipate the net dust production efficiency of CCSNe. Dust polarisation levels sensitively depend on the size, shape and composition of dust grains, and provide a unique way of constraining the nature of supernova dust species. We propose SOFIA HAWC+ polarimetric observations of the Crab Nebula at 89 and 154 micron targeting the peak of the dust SED emission. The Crab Nebula is an obvious target for dust polarisation studies with the recent detection of a large dust reservoir (0.2-0.5 Msun) and the absence of any surrounding ISM material that could contaminate dust polarimetric observations. The characterisation of grain composition will allow us to quantify the exact mass of freshly condensed grains in the Crab Nebula and will provide invaluable constraints on the carbon yields for nucleosynthesis models of progenitors with initial masses of 9-10 Msun. The inferred grain size will be crucial to determine the resistance of supernova dust to shocks and to infer the net supernova dust mass that is eventually injected into the ISM, which is vital to understand whether CCSNe are able to account for the large dust masses detected in high-redshift galaxies.