SNLS-03D3bb

[Ruth Lazkoz]

Hi,

Can anyone illustrate us on the implications of the peculiar behavior of SNLS-03D3bb on cosmological parameter determination?

Thanks,

Ruth

[Tommy Anderberg]

Can anyone illustrate us on the implications of the peculiar behavior of SNLS-03D3bb on cosmological parameter determination?

You may want to ask John Middleditch (he's in the member list, hopefully reading and willing to comment). I have been waiting for somebody to bring up his recent astro-ph/0608386, and can't help but notice that his idea, i.e. that (quoting from the abstract) a "Ia/c is produced from the merger of two degenerate cores of common envelope WR stars, or of two CO white dwarfs", seems to offer a natural explanation for the excessive mass of SNLS-03D3bb (2.1 solar masses vs the Chandrasekhar limit of 1.4). If he is right and this is the paradigm, then there's trouble; he says that the resulting errors could completely wipe out the observed acceleration effect (see his paper).

For now I suspect most people are likely to go along with what Riess says in this Nature piece:

If one or two are odd, it's not a problem. I would be more worried if these weirdos were around the 10% level — if they had found 20 weirdos

But (speaking as a total know-nothing as far as supernova explosion mechanisms are concerned) I feel uneasy. It seems to me that SNLS-03D3bb could be

1) a freak that shows the Middleditch paradigm (or some other explanation, like the large spin suggested by Howell) is viable but not necessarily frequent, with most SNe Ia still explained by the standard paradigm (this seems to be what Riess is saying)

or

2) unusual simply because of its large total mass; by continuity, there should be smaller ones too, but we can't easily tell those apart from standard paradigm SNe Ia, so we don't know how contaminated the "standard candle" sample is.