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[astro-ph/0609616] The type Ia supernova SNLS-03D3bb from a super-Chandrasekhar-mass white dwarf star
 
Authors:D. Andrew Howell, Mark Sullivan, Peter E. Nugent, Richard S. Ellis, Alexander J. Conley, Damien Le Borgne, Raymond G. Carlberg, Julien Guy, David Balam, Stephane Basa, Dominique Fouchez, Isobel M. Hook, Eric Y. Hsiao, James D. Neill, Reynald
Abstract:The acceleration of the expansion of the universe, and the need for Dark Energy, were inferred from the observations of Type Ia supernovae (SNe Ia). There is consensus that SNe Ia are thermonuclear explosions that destroy carbon-oxygen white dwarf stars that accrete matter from a companion star, although the nature of this companion remains uncertain. SNe Ia are thought to be reliable distance indicators because they have a standard amount of fuel and a uniform trigger -- they are predicted to explode when the mass of the white dwarf nears the Chandrasekhar mass -- 1.4 solar masses. Here we show that the high redshift supernova SNLS-03D3bb has an exceptionally high luminosity and low kinetic energy that both imply a super-Chandrasekhar mass progenitor. Super-Chandrasekhar mass SNe Ia should preferentially occur in a young stellar population, so this may provide an explanation for the observed trend that overluminous SNe Ia only occur in young environments. Since this supernova does not obey the relations that allow them to be calibrated as standard candles, and since no counterparts have been found at low redshift, future cosmology studies will have to consider contamination from such events.
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Alessandro Melchiorri



Joined: 24 Sep 2004
Posts: 123
Affiliation: University of Rome

PostPosted: January 27 2007  Reply with quote

Hi,

This paper sounds to me like a very interesting result, but no one discussed it on cosmocoffee (unless I missed some posts) !
You have a SN-Ia supernovae from a white dwarf with mass greater than the
Chandrasekhar mass !
This paper went out on Nature last September, any comment or progress after ?

Cheers
Alessandro
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Tommy Anderberg



Joined: 24 Nov 2005
Posts: 47
Affiliation: independent

PostPosted: January 27 2007  Reply with quote

Alessandro Melchiorri wrote:
This paper sounds to me like a very interesting result, but no one discussed it on cosmocoffee (unless I missed some posts) !

It was fist mentioned here, under "Cosmological model". I found the possible connection to the Middleditch paper astro-ph/0608386 interesting. He didn't comment at the time, but subsequently mentioned it in the thread on Vishwakarma's supernova paper. Then astro-ph/0611902 came out, and as far as I can see it throws some cold water on the idea that core merger events are frequently occurring, since they consistently see central symmetry, with the asymmetry emerging further out. Granted, their sample is small.

When I last checked (late December) two unanswered questions loomed big in my little mind:

1) Is SNLS−03D3bb a freak or the tip of an iceberg (i.e. unusually large mass but otherwise unexceptional, meaning there is a larger population of smaller ones contaminating SNe Ia data)?

2) What's the effect of astro-ph/0611902 on luminosity/distance error bars in cold, hard numbers?
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