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Thread: Type Ia supernovae as standard candles

  1. #1
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    Type Ia supernovae as standard candles

    I have seen some comments about different types of Ia supernovae and what this might mean for their use as standard candles.

    For example: https://www.eurekalert.org/pub_relea...-aun041015.php (I did skim the linked paper, but it is probably a bit over my head!)

    How great an effect is this likely to have? Will it (possibly) just change the rate of acceleration of expansion? Or could it be enough to eliminate the evidence for acceleration? Are there any other questions that might be resolved by this? (e.g. I have seen something about two different methods giving different values for the Hubble constant)

  2. #2
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    We have a few members with more involvement here, so I anticipate clarification from them soon, but to give a short hand-waving answer: Work has been done to find ways to identify subcategories of Type 1a SN, in hopes of finding something closer to being the same brightness every time, specifically looking for indicators that an SN 1a is single or double degenerate. The single Degenerate ones being likely to be reliably standard candles within a few percent, or alternatively for double degenerates, finding a formula for something that can be measured that computes the actual luminosity. In any case, the now statistically large number of observed SNs tells us that expansion IS accelerating.
    Forming opinions as we speak

  3. #3
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    Yes, I'd say it's pretty much down to trying to better constrain the acceleration and reduce the scatter in the SN data, moreso than deciding if it's there or not. The paper you cite hasn't really made that much of a splash in the 3 years it has been around, it seems that people regard it as a kind of detail.

  4. #4
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    Some observers have looked for additional evidence that the two populations of type Ia SNe, distinct in their near-UV behaviour, really exist. This paper:

    http://adsabs.harvard.edu/abs/2017MNRAS.466..884C

    fails to find such evidence, and suggests that there may not be such a distinction.

  5. #5
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    Quote Originally Posted by StupendousMan View Post
    Some observers have looked for additional evidence that the two populations of type Ia SNe, distinct in their near-UV behaviour, really exist. This paper:

    http://adsabs.harvard.edu/abs/2017MNRAS.466..884C

    fails to find such evidence, and suggests that there may not be such a distinction.
    Thanks for that - and the other replies. Sounds like more work is required but it probably isn't going to make a huge difference.

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