A hierarchical model for the ages of Galactic halo white dwarfs

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Title: A hierarchical model for the ages of Galactic halo white dwarfs
Author(s): Si, S
Van Dyk, DA
Von Hippel, T
Robinson, E
Webster, A
Stenning, D
Item Type: Journal Article
Abstract: In astrophysics, we often aim to estimate one or more parameters for each member object in a population and study the distribution of the fitted parameters across the population. In this paper, we develop novel methods that allow us to take advantage of existing software designed for such case-by-case analyses to simultaneously fit parameters of both the individual objects and the parameters that quantify their distribution across the population. Our methods are based on Bayesian hierarchical modelling that is known to produce parameter estimators for the individual objects that are on average closer to their true values than estimators based on case-by-case analyses. We verify this in the context of estimating ages of Galactic halo white dwarfs (WDs) via a series of simulation studies. Finally, we deploy our new techniques on optical and near-infrared photometry of 10 candidate halo WDs to obtain estimates of their ages along with an estimate of the mean age of Galactic halo WDs of 12.11+0.85−0.86 Gyr. Although this sample is small, our technique lays the ground work for large-scale studies using data from the Gaia mission.
Publication Date: 29-Mar-2017
Date of Acceptance: 29-Mar-2017
URI: http://hdl.handle.net/10044/1/46138
DOI: https://dx.doi.org/10.1093/mnras/stx765
ISSN: 1365-2966
Publisher: Oxford University Press (OUP)
Start Page: 4374
End Page: 4388
Journal / Book Title: Monthly Notices of the Royal Astronomical Society
Volume: 468
Issue: 4
Sponsor/Funder: Commission of the European Communities
Commission of the European Communities
Funder's Grant Number: 691164
Copyright Statement: © 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. This article has been accepted for publication in MNRAS.
Keywords: Astronomy & Astrophysics
0201 Astronomical And Space Sciences
Publication Status: Published
Appears in Collections:Mathematics
Faculty of Natural Sciences

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