Gamma-ray line emission from OB associations and young open clusters: I. Evolutionary synthesis models

TL;DR

This paper introduces a new evolutionary synthesis model for gamma-ray line emission from radioactive isotopes in stellar clusters, incorporating recent stellar evolution data and a Bayesian analysis approach.

Contribution

The paper presents an updated synthesis model for gamma-ray emission, integrating recent stellar evolution tracks, atmospheres, and nucleosynthetic yields, with a Bayesian framework for data analysis.

Findings

Model predicts temporal evolution of 26Al and 60Fe production.

Estimates steady state nucleosynthesis for solar metallicity populations.

Demonstrates Bayesian approach for analyzing multi-wavelength observations.

Abstract

We have developed a new diagnostic tool for the study of gamma-ray emission lines from radioactive isotopes (such as 26Al and 60Fe in conjunction with other multi-wavelength observables of Galactic clusters, associations, and alike objects. Our evolutionary synthesis models are based on the code of Cervino & Mas-Hesse (1994), which has been updated to include recent stellar evolution tracks, new stellar atmospheres for OB and WR stars, and nucleosynthetic yields from massive stars during hydrostatic burning phases and explosive SN II and SN Ib events. The temporal evolution of 26Al and 60Fe production, the equivalent yield of 26Al per ionising O7 V star (yal), and other observables are predicted for a coeval population. We also employed our model to estimate the steady state nucleosynthesis of a population of solar metallicity. To allow for a fully quantitative analysis of existing and future multi-wavelength observations, we propose a Bayesian approach that allows the inclusion of IMF richness effects and observational uncertainties in the analysis. In particular, a Monte Carlo technique is adopted to estimate probability distributions for all observables of interest. We outline the procedure of exploiting these distributions by applying our model to a fictive massive star association. Applications to existing observations of the Cygnus and Vela regions will be discussed in companion papers.