skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: zBEAMS: a unified solution for supernova cosmology with redshift uncertainties

Abstract

Supernova cosmology without spectra will be an important component of future surveys such as LSST. This lack of supernova spectra results in uncertainty in the redshifts which, if ignored, leads to significantly biased estimates of cosmological parameters. Here we present a hierarchical Bayesian formalism— zBEAMS—that addresses this problem by marginalising over the unknown or uncertain supernova redshifts to produce unbiased cosmological estimates that are competitive with supernova data with spectroscopically confirmed redshifts. zBEAMS provides a unified treatment of both photometric redshifts and host galaxy misidentification (occurring due to chance galaxy alignments or faint hosts), effectively correcting the inevitable contamination in the Hubble diagram. Like its predecessor BEAMS, our formalism also takes care of non-Ia supernova contamination by marginalising over the unknown supernova type. We illustrate this technique with simulations of supernovae with photometric redshifts and host galaxy misidentification. A novel feature of the photometric redshift case is the important role played by the redshift distribution of the supernovae.

Authors:
; ; ; ;  [1];  [2]
  1. African Institute for Mathematical Sciences, 6 Melrose Road, Muizenberg, 7945, Cape Town (South Africa)
  2. Department of Physics and Astronomy, University of the Western Cape, Cape Town 7535 (South Africa)
Publication Date:
OSTI Identifier:
22667637
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2017; Journal Issue: 10; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BEAMS; COSMOLOGY; DISTRIBUTION; GALAXIES; RED SHIFT; SIMULATION; SPECTRA; SUPERNOVAE

Citation Formats

Roberts, Ethan, Lochner, Michelle, Bassett, Bruce A., Lablanche, Pierre-Yves, Agarwal, Shankar, and Fonseca, José, E-mail: rbreth001@myuct.ac.za, E-mail: michelle@aims.ac.za, E-mail: jfonseca@uwc.ac.za, E-mail: bruce.a.bassett@gmail.com, E-mail: plablanche@aims.ac.za, E-mail: agarwalshankar@aims.ac.za. zBEAMS: a unified solution for supernova cosmology with redshift uncertainties. United States: N. p., 2017. Web. doi:10.1088/1475-7516/2017/10/036.
Roberts, Ethan, Lochner, Michelle, Bassett, Bruce A., Lablanche, Pierre-Yves, Agarwal, Shankar, & Fonseca, José, E-mail: rbreth001@myuct.ac.za, E-mail: michelle@aims.ac.za, E-mail: jfonseca@uwc.ac.za, E-mail: bruce.a.bassett@gmail.com, E-mail: plablanche@aims.ac.za, E-mail: agarwalshankar@aims.ac.za. zBEAMS: a unified solution for supernova cosmology with redshift uncertainties. United States. doi:10.1088/1475-7516/2017/10/036.
Roberts, Ethan, Lochner, Michelle, Bassett, Bruce A., Lablanche, Pierre-Yves, Agarwal, Shankar, and Fonseca, José, E-mail: rbreth001@myuct.ac.za, E-mail: michelle@aims.ac.za, E-mail: jfonseca@uwc.ac.za, E-mail: bruce.a.bassett@gmail.com, E-mail: plablanche@aims.ac.za, E-mail: agarwalshankar@aims.ac.za. Sun . "zBEAMS: a unified solution for supernova cosmology with redshift uncertainties". United States. doi:10.1088/1475-7516/2017/10/036.
@article{osti_22667637,
title = {zBEAMS: a unified solution for supernova cosmology with redshift uncertainties},
author = {Roberts, Ethan and Lochner, Michelle and Bassett, Bruce A. and Lablanche, Pierre-Yves and Agarwal, Shankar and Fonseca, José, E-mail: rbreth001@myuct.ac.za, E-mail: michelle@aims.ac.za, E-mail: jfonseca@uwc.ac.za, E-mail: bruce.a.bassett@gmail.com, E-mail: plablanche@aims.ac.za, E-mail: agarwalshankar@aims.ac.za},
abstractNote = {Supernova cosmology without spectra will be an important component of future surveys such as LSST. This lack of supernova spectra results in uncertainty in the redshifts which, if ignored, leads to significantly biased estimates of cosmological parameters. Here we present a hierarchical Bayesian formalism— zBEAMS—that addresses this problem by marginalising over the unknown or uncertain supernova redshifts to produce unbiased cosmological estimates that are competitive with supernova data with spectroscopically confirmed redshifts. zBEAMS provides a unified treatment of both photometric redshifts and host galaxy misidentification (occurring due to chance galaxy alignments or faint hosts), effectively correcting the inevitable contamination in the Hubble diagram. Like its predecessor BEAMS, our formalism also takes care of non-Ia supernova contamination by marginalising over the unknown supernova type. We illustrate this technique with simulations of supernovae with photometric redshifts and host galaxy misidentification. A novel feature of the photometric redshift case is the important role played by the redshift distribution of the supernovae.},
doi = {10.1088/1475-7516/2017/10/036},
journal = {Journal of Cosmology and Astroparticle Physics},
number = 10,
volume = 2017,
place = {United States},
year = {Sun Oct 01 00:00:00 EDT 2017},
month = {Sun Oct 01 00:00:00 EDT 2017}
}