Hierarchical Bayesian approach for estimating physical properties in nearby galaxies: Age Maps (Paper II)

DOI:
10.1093/mnras/sty3106
Publication date:
01/02/2019
Main author:
Sánchez-Gil, M. Carmen
IAA authors:
Sánchez-Gil, M. Carmen;Alfaro, Emilio J.;Cerviño, Miguel;Pérez, Enrique
Authors:
Sánchez-Gil, M. Carmen;Alfaro, Emilio J.;Cerviño, Miguel;Pérez, Enrique;Bland-Hawthorn, Joss;Jones, D. Heath
Journal:
Monthly Notices of the Royal Astronomical Society
Refereed:
Yes
Publication type:
Article
Volume:
483
Pages:
2641-2670
Abstract:
One of the fundamental goals of modern astrophysics is to estimate the physical parameters of galaxies. We present a hierarchical Bayesian model to compute age maps from images in the H α line (taken with Taurus tunable filter, TTF), ultraviolet band (GALEX far UV, FUV), and infrared bands (Spitzer 24, 70, and 160 μm). We present the burst ages for young stellar populations in a sample of nearby and nearly face-on galaxies. The H α to FUV flux ratio is a good relative indicator of the very recent star formation history (SFH). As a nascent star-forming region evolves, the H α line emission declines earlier than the UV continuum, leading to a decrease in the H α/FUV ratio. Using star-forming galaxy models, sampled with a probabilistic formalism, and allowing for a variable fraction of ionizing photons in the clusters, we obtain the corresponding theoretical ratio H α/FUV to compare with our observed flux ratios, and thus to estimate the ages of the observed regions. We take into account the mean uncertainties and the interrelationships between parameters when computing H α/FUV. We propose a Bayesian hierarchical model where a joint probability distribution is defined to determine the parameters (age, metallicity, IMF) from the observed data (the observed flux ratios H α/FUV). The joint distribution of the parameters is described through independent and identically distributed (i.i.d.) random variables generated through MCMC (Markov Chain Monte Carlo) techniques.
Database:
ADS
SCOPUS
URL:
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85066998011&doi=10.1093%2fmnras%2fsty3106&partnerID=40&md5=af004dcf0be439d1ca81ccec647a726c
ADS Bibcode:
2019MNRAS.483.2641S
Keywords:
methods: observational;methods: statistical;galaxies: spiral;galaxies: starburst;galaxies: star formation;galaxies: structure;Astrophysics - Astrophysics of Galaxies