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Type Ia supernovae, standardizable candles, and gravity.

Wright, Bill S. and Li, Baojiu (2018) 'Type Ia supernovae, standardizable candles, and gravity.', Physical review D., 97 (8). 083505.

Abstract

Type Ia supernovae (SNe Ia) are generally accepted to act as standardizable candles, and their use in cosmology led to the first confirmation of the as yet unexplained accelerated cosmic expansion. Many of the theoretical models to explain the cosmic acceleration assume modifications to Einsteinian general relativity which accelerate the expansion, but the question of whether such modifications also affect the ability of SNe Ia to be standardizable candles has rarely been addressed. This paper is an attempt to answer this question. For this we adopt a semianalytical model to calculate SNe Ia light curves in non-standard gravity. We use this model to show that the average rescaled intrinsic peak luminosity—a quantity that is assumed to be constant with redshift in standard analyses of Type Ia supernova (SN Ia) cosmology data—depends on the strength of gravity in the supernova’s local environment because the latter determines the Chandrasekhar mass—the mass of the SN Ia’s white dwarf progenitor right before the explosion. This means that SNe Ia are no longer standardizable candles in scenarios where the strength of gravity evolves over time, and therefore the cosmology implied by the existing SN Ia data will be different when analysed in the context of such models. As an example, we show that the observational SN Ia cosmology data can be fitted with both a model where ( Ω M , Ω Λ ) = ( 0.62 , 0.38 ) and Newton’s constant G varies as G ( z ) = G 0 ( 1 + z ) − 1 / 4 and the standard model where ( Ω M , Ω Λ ) = ( 0.3 , 0.7 ) and G is constant, when the Universe is assumed to be flat.

Item Type:Article
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Status:Peer-reviewed
Publisher Web site:https://doi.org/10.1103/PhysRevD.97.083505
Publisher statement:Reprinted with permission from the American Physical Society: Wright, Bill S. & Li, Baojiu (2018). Type Ia supernovae, standardizable candles, and gravity. Physical Review D 97(8): 083505 © 2018 by the American Physical Society. Readers may view, browse, and/or download material for temporary copying purposes only, provided these uses are for noncommercial personal purposes. Except as provided by law, this material may not be further reproduced, distributed, transmitted, modified, adapted, performed, displayed, published, or sold in whole or part, without prior written permission from the American Physical Society.
Date accepted:27 October 2017
Date deposited:26 April 2018
Date of first online publication:09 April 2018
Date first made open access:26 April 2018

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