Projected distances to host galaxy reduce SNIa dispersion

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Title: Projected distances to host galaxy reduce SNIa dispersion
Author(s): Hill, R
Shariff, H
Trotta, R
Ali-Khan, S
Jiao, X
Liu, Y
Moon, SK
Parker, W
Paulus, M
Dyk, DAV
Lucy, LB
Item Type: Journal Article
Abstract: We use multi-band imagery data from the Sloan Digital Sky Survey (SDSS) to measure projected distances of 302 supernova type Ia (SNIa) from the centre of their host galaxies, normalized to the galaxy's brightness scale length, with a Bayesian approach. We test the hypothesis that SNIas further away from the centre of their host galaxy are less subject to dust contamination (as the dust column density in their environment is maller) and/or come from a more homogeneous environment. Using the Mann-Whitney U test, we find a statistically significant difference in the observed colour correction distribution between SNIas that are near and those that are far from the centre of their host. The local p-value is 3 x 10^{-3}, which is significant at the 5 per cent level after look-elsewhere effect correction. We estimate the residual scatter of the two subgroups to be 0.073 +/- 0.018 for the far SNIas, compared to 0.114 +/-0.009 for the near SNIas -- an improvement of 30 per cent, albeit with a low statistical significance of 2sigma. This confirms the importance of host galaxy properties in correctly interpreting SNIa observations for cosmological inference.
Publication Date: 31-Dec-2018
Date of Acceptance: 7-Sep-2018
ISSN: 0035-8711
Publisher: Oxford University Press (OUP)
Start Page: 2766
End Page: 2777
Journal / Book Title: Monthly Notices of the Royal Astronomical Society
Volume: 481
Issue: 2
Sponsor/Funder: Imperial College Trust
Engineering & Physical Science Research Council (E
Science and Technology Facilities Council (STFC)
Science and Technology Facilities Council (STFC)
Science and Technology Facilities Council [2006-2012]
Science and Technology Facilities Council [2006-2012]
European Commission
Science and Technology Facilities Council
Science and Technology Facilities Council (STFC)
Funder's Grant Number: NA
Copyright Statement: © 2018 The Author(s). Published by Oxford University Press on behalf of The Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
Keywords: astro-ph.GA
0201 Astronomical And Space Sciences
Astronomy & Astrophysics
Publication Status: Published
Online Publication Date: 2018-09-14
Appears in Collections:Physics
Faculty of Natural Sciences

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