Imperial College London
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ProfessorRobertoTrotta

Faculty of Natural Sciences, Department of Physics

Visiting Professor
 
 
 
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Contact

 

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

 
 
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Assistant

 

Mrs Sheila Ekudo +44 (0)20 7594 2086

 
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Location

 

1009Blackett LaboratorySouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Rahman:2022:mnras/stac1223,
author = {Rahman, W and Trotta, R and Boruah, SS and Hudson, MJ and Dyk, DAV},
doi = {mnras/stac1223},
journal = {Monthly Notices of the Royal Astronomical Society},
pages = {139--163},
title = {New constraints on anisotropic expansion from supernovae type Ia},
url = {http://dx.doi.org/10.1093/mnras/stac1223},
volume = {514},
year = {2022}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - We re-examine the contentious question of constraints on anisotropic expansion from Type Ia supernovae (SNIa) in the light of a novel determination of peculiar velocities, which are crucial to test isotropy with SNe out to distances 200h-1 Mpc. We re-analyse the Joint Light-Curve Analysis (JLA) Supernovae (SNe) data, improving on previous treatments of peculiar velocity corrections and their uncertainties (both statistical and systematic) by adopting state-of-the-art flow models constrained independently via the 2M++ galaxy redshift compilation. We also introduce a novel procedure to account for colour-based selection effects, and adjust the redshift of low-z SNe self-consistently in the light of our improved peculiar velocity model. We adopt the Bayesian hierarchical model BAHAMAS to constrain a dipole in the distance modulus in the context of the Lambda cold dark matter (ΛCDM) model and the deceleration parameter in a phenomenological Cosmographic expansion. We do not find any evidence for anisotropic expansion, and place a tight upper bound on the amplitude of a dipole, |Dμ| < 5.93 × 10−4 (95 per cent credible interval) in a ΛCDM setting, and |Dq0|<6.29×10−2 in the Cosmographic expansion approach. Using Bayesian model comparison, we obtain posterior odds in excess of 900:1 (640:1) against a constant-in-redshift dipole for ΛCDM (the Cosmographic expansion). In the isotropic case, an accelerating universe is favoured with odds of ∼1100:1 with respect to a decelerating one.
AU  - Rahman,W
AU  - Trotta,R
AU  - Boruah,SS
AU  - Hudson,MJ
AU  - Dyk,DAV
DO  - mnras/stac1223
EP  - 163
PY  - 2022///
SN  - 0035-8711
SP  - 139
TI  - New constraints on anisotropic expansion from supernovae type Ia
T2  - Monthly Notices of the Royal Astronomical Society
UR  - http://dx.doi.org/10.1093/mnras/stac1223
UR  - http://arxiv.org/abs/2108.12497v2
UR  - https://academic.oup.com/mnras/article/514/1/139/6577136
UR  - http://hdl.handle.net/10044/1/97118
VL  - 514
ER  -
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