DAmodel: Hierarchical Bayesian Modelling of DA White Dwarfs for Spectrophotometric Calibration

Published

December 11, 2024

Author(s)

Benjamin M. Boyd, Gautham Narayan, Kaisey Mandel, Matthew Grayling, Aidan Berres, Mai Li, Aaron Do, ABHIJIT SAHA, Tim Axelrod, Thomas Matheson, Edward W Olszewski, ralph bohlin, Annalisa Calamida, Jenna Claver, Susana Deustua, Jay Holberg, Ivan Hubeny, John MacKenty, Konstantin Malanchev, Sean Points, Armin Rest, Elena Sabbi, Christopher Stubbs

Abstract

standards (16.5 < V < 19.5) alongside the three CALSPEC standards, from 900 Å to 32 μm. The framework is the first of its kind to jointly infer photometric zeropoints and WD parameters (log g, Teff, AV , RV ) by simultaneously modelling both photometric and spectroscopic data. We model panchromatic HST/WFC3 UVIS and IR fluxes, HST/STIS UV spectroscopy and ground-based optical spectroscopy to sub-percent precision. Photometric residuals for the sample are the lowest yet yielding < 4 mmag RMS on average from the UV to the NIR, achieved by jointly inferring changing zeropoints across HST cycles, as well as the F160W count rate non-linearity. Our GPU-accelerated implementation allows efficient sampling via Hamiltonian Monte Carlo, critical for exploring the high-dimensional posterior space. The hierarchical nature of the model enables population analysis of intrinsic WD and dust parameters. Inferred SEDs from this model will be essential for calibrating next-generation surveys, including the James Webb Space Telescope, Vera Rubin Observatory's Legacy Survey of Space and Time, and the Nancy Grace Roman Space Telescope.

Citation

Astrophysical Journal

Pub Type

Journals

Keywords

white dwarfs, surveys, standard stars

Citation

Boyd, B. , Narayan, G. , Mandel, K. , Grayling, M. , Berres, A. , Li, M. , Do, A. , Saha, A. , Axelrod, T. , Matheson, T. , Olszewski, E. , Bohlin, R. , Calamida, A. , Claver, J. , Deustua, S. , Holberg, J. , Hubeny, I. , MacKenty, J. , Malanchev, K. , Points, S. , Rest, A. , Sabbi, E. and Stubbs, C. (2024), DAmodel: Hierarchical Bayesian Modelling of DA White Dwarfs for Spectrophotometric Calibration, Astrophysical Journal (Accessed January 17, 2025)