The influence of accretion rate and metallicity on thermonuclear bursts: predictions from KEPLER models

TL;DR

This study uses KEPLER models to analyze how accretion rate and metallicity influence thermonuclear X-ray bursts, revealing relationships between these parameters and burst characteristics.

Contribution

It provides a comprehensive library of simulated burst profiles and identifies how accretion rate and metallicity affect burst recurrence and morphology.

Findings

Recurrence time follows a power law with accretion rate, slope varies from 1.1 to 1.24.

Transition points in burning regimes depend on accretion rate and metallicity.

Burst morphology changes with accretion rate and metallicity.

Abstract

Using the KEPLER hydrodynamics code, 464 models of thermonuclear X-ray bursters were performed across a range of accretion rates and compositions. We present the library of simulated burst profiles from this sample, and examine variations in the simulated lightcurve for different model conditions. We find that the recurrence time varies as a power law against accretion rate, and measure its slope while mixed H/He burning is occurring for a range of metallicities, finding the power law gradient to vary from $\eta = 1.1$ to $1.24$. We also identify the accretion rates at which mixed H/He burning stops and a transition occurs to different burning regimes. We also explore how varying the accretion rate and metallicity affects burst morphology in both the rise and tail.