IP2: Millimetre and submillimetre observations of dust and molecules in supernova young remnants

The amount of dust produced by supernovae is still under controversy. Observations carried on in the infrared are blind to cold dust emission and are limited in angular resolution. Complementary observations are therefore required in the millimetre/submillimetre domain, in order to obtain a complete picture of the dust. In addition, carbon monoxide (CO) molecules have been detected in several remnants and chemical models predict a rich molecular chemistry in the ejecta. For a sample of supernova (SN) young remnants with different ages and metallicities, this IP aims at carrying on systematic observations at millimetre and submillimetre wavelengths in order to study their dust and molecular contents.

The IP objectives are:

• The measurement of the dust thermal emission and the mapping of its spatial distribution in the remnants to derive dust mass yields and test theoretical prescriptions on the dust formation processes in the SN phase and its further evolution in young remnants.

• A parallel search for molecular species predicted to form in SN ejecta, and commonly observed in the circumstellar envelopes of evolved stars.

Indeed, molecules can be used as observational tracers of post-explosion mixing in SN ejecta and remnants, providing unique information on the chemistry and the kinematics of these gaseous media. Such a systematic search in SN remnants is novel. Typical molecules expected to form in significant amounts are O2, SiS, CO and SO and a recent infrared detection of CO in Cas A suggests that molecules exist or continue forming long after the explosion event. CO molecules are particularly important to the dust formation process, as they lock up the elemental carbon otherwise available for carbon grain condensation. CO is also an effective coolant and its observation will provide a diagnostic of the physical conditions (i.e., gas temperature and density) in the inhomogeneous SN remnants. We will concentrate on the Cas A and Kepler remnants, as well as on SNe in the low metallicity environment of the Magellanic Clouds, as prototypes of SNe at high redshifts.

Collaborators at the Onsala Observatory:

Dr. Sebastien Muller (IP leader)

Prof. John Black (co-IP leader)

Ms. Sofia Wallström (PhD student)