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 = {Shariff, H and Dhawan, S and Jiao, X and Leibundgut, B and Trotta, R and Van, Dyk DA},
doi = {mnras/stw2278},
journal = {Monthly Notices of the Royal Astronomical Society},
pages = {4311--4316},
title = {Standardizing type Ia supernovae optical brightness using near infrared rebrightening time},
url = {},
volume = {463},
year = {2016}

RIS format (EndNote, RefMan)

AB - Accurate standardization of Type Ia supernovae (SNIa) is instrumental to theusage of SNIa as distance indicators. We analyse a homogeneous sample of 22 lowzSNIa, observed by the Carnegie Supernova Project (CSP) in the optical and nearinfra-red (NIR). We study the time of the second peak in the J-band, t2, as an alternativestandardization parameter of SNIa peak optical brightness, as measured by thestandard SALT2 parameter mB. We use BAHAMAS, a Bayesian hierarchical modelfor SNIa cosmology, to estimate the residual scatter in the Hubble diagram.We find that in the absence of a colour correction, t2 is a better standardizationparameter compared to stretch: t2 has a 1σ posterior interval for the Hubble residualscatter of σµ = {0.250, 0.257} mag, compared to σµ = {0.280, 0.287} mag whenstretch (x1) alone is used. We demonstrate that when employed together with a colourcorrection, t2 and stretch lead to similar residual scatter. Using colour, stretch andt2 jointly as standardization parameters does not result in any further reduction inscatter, suggesting that t2 carries redundant information with respect to stretch andcolour. With a much larger SNIa NIR sample at higher redshift in the future, t2 couldbe a useful quantity to perform robustness checks of the standardization procedure.
AU - Shariff,H
AU - Dhawan,S
AU - Jiao,X
AU - Leibundgut,B
AU - Trotta,R
AU - Van,Dyk DA
DO - mnras/stw2278
EP - 4316
PY - 2016///
SN - 1365-2966
SP - 4311
TI - Standardizing type Ia supernovae optical brightness using near infrared rebrightening time
T2 - Monthly Notices of the Royal Astronomical Society
UR -
UR -
VL - 463
ER -