Imperial College London


Faculty of Natural SciencesDepartment of Physics

Professor of Astrostatistics; CLCC Director



+44 (0)20 7594 7793r.trotta Website CV




Mrs Sheila Ekudo +44 (0)20 7594 2086




1009Blackett LaboratorySouth Kensington Campus






BibTex format

author = {Hill, R and Shariff, H and Trotta, R and Ali-Khan, S and Jiao, X and Liu, Y and Moon, SK and Parker, W and Paulus, M and Dyk, DAV and Lucy, LB},
doi = {mnras/sty2510},
journal = {Monthly Notices of the Royal Astronomical Society},
pages = {2766--2777},
title = {Projected distances to host galaxy reduce SNIa dispersion},
url = {},
volume = {481},
year = {2018}

RIS format (EndNote, RefMan)

AB - 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 thetwo 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.
AU - Hill,R
AU - Shariff,H
AU - Trotta,R
AU - Ali-Khan,S
AU - Jiao,X
AU - Liu,Y
AU - Moon,SK
AU - Parker,W
AU - Paulus,M
AU - Dyk,DAV
AU - Lucy,LB
DO - mnras/sty2510
EP - 2777
PY - 2018///
SN - 0035-8711
SP - 2766
TI - Projected distances to host galaxy reduce SNIa dispersion
T2 - Monthly Notices of the Royal Astronomical Society
UR -
UR -
VL - 481
ER -