Affiliation
Department of Astronomy, University of ArizonaSteward Observatory, University of Arizona
Issue Date
2022Keywords
Cosmological parametersCosmology: observations
Dark energy
Methods: statistical
Supernovae: general
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Oxford University PressCitation
Rahman, W., Trotta, R., Boruah, S. S., Hudson, M. J., & Van Dyk, D. A. (2022). New constraints on anisotropic expansion from supernovae Type Ia. Monthly Notices of the Royal Astronomical Society, 514(1), 139–163.Rights
Copyright © The Author(s) 2022. Published by Oxford University Press on behalf of Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/).Collection Information
This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.Abstract
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 |D q 0| < 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. © 2022 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society.Note
Open access articleISSN
0035-8711Version
Final published versionae974a485f413a2113503eed53cd6c53
10.1093/mnras/stac1223
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Except where otherwise noted, this item's license is described as Copyright © The Author(s) 2022. Published by Oxford University Press on behalf of Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/).