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Direction dependence in supernova data: constraining isotropy

Gupta, Shashikant and Saini, Tarun Deep (2010) Direction dependence in supernova data: constraining isotropy. In: Monthly Notices of the Royal Astronomical Society, 407 (1). pp. 651-657.

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Official URL: http://onlinelibrary.wiley.com/doi/10.1111/j.1365-...


We revise and extend the extreme value statistic, introduced in Gupta et al., to study direction dependence in the high-redshift supernova data, arising either from departures, from the cosmological principle or due to direction-dependent statistical systematics in the data. We introduce a likelihood function that analytically marginalizes over the,Hubble constant and use it to extend our previous statistic. We also introduce a new statistic that is sensitive to direction dependence arising from living off-centre inside a large void as well as from previously mentioned reasons for anisotropy. We show that for large data sets, this statistic has a limiting form that can be computed analytically. We apply our statistics to the gold data sets from Riess et al., as in our previous work. Our revision and extension of the previous statistic show that the effect of marginalizing over the Hubble constant instead of using its best-fitting value on our results is only marginal. However, correction of errors in our previous work reduces the level of non-Gaussianity in the 2004 gold data that were found in our earlier work. The revised results for the 2007 gold data show that the data are consistent with isotropy and Gaussianity. Our second statistic confirms these results.

Item Type: Journal Article
Publication: Monthly Notices of the Royal Astronomical Society
Publisher: John Wiley and Sons
Additional Information: Copyright of this article belongs to John Wiley and Sons.
Keywords: Supernovae: general; cosmological parameters; large-scale structure of Universe.
Department/Centre: Others
Date Deposited: 16 Sep 2010 06:19
Last Modified: 16 Sep 2010 06:19
URI: http://eprints.iisc.ac.in/id/eprint/32123

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