Short-lived Radionuclides in the Milky Way Galaxy

Abstract

The short-lived radionuclides (SLRs) have a half-life $\leq$ 100 Myr. The $\gamma$-ray observations and excess abundance of their daughter nuclides in various meteoritic phases confirm the existence of SLRs in the Galaxy and early solar system (ESS), respectively. In this work, we have developed Galactic Chemical Evolution (GCE) models for SLRs, $^{26}$Al, and $^{60}$Fe along with $^{36}$Cl, $^{41}$Ca, and $^{53}$Mn. These models predict the temporal and spatial evolution of SLR abundance trends in the Galaxy from 2-18 kpc. The abundance of two SLRs, $^{26}$Al, and $^{60}$Fe, are investigated further, as their $\gamma$-ray observations are available for comparison with the model predictions. The predictions for the abundance per unit area for each ring decrease from the inner to outer regions of the Galaxy.The GCE predictions for the total mass of alive $^{26}$Al, and $^{60}$Fe in 2-18 kpc of the Galaxy at present time are 0.2 M$_\odot$ and 0.08 M$_\odot$, respectively.