The Fundamental Plane of Gamma-ray Globular Clusters

TL;DR

This study explores the relationships between gamma-ray luminosity and various properties of globular clusters, revealing correlations and potential fundamental planes that enhance understanding of high-energy emissions from these clusters.

Contribution

It identifies key correlations between gamma-ray luminosity and cluster properties, proposing a fundamental plane model for better prediction of gamma-ray emissions.

Findings

$L_{ m b3}$ correlates with encounter rate $\u03b3_c$ and metallicity [Fe/H]

$L_{ m b3}$ increases with soft photon energy densities

Gamma-ray luminosity, photon densities, and cluster properties form fundamental planes

Abstract

We have investigated the properties of a group of $\gamma$-ray emitting globular clusters (GCs) which have recently been uncovered in our Galaxy. By correlating the observed $\gamma$-ray luminosities $L_{\gamma}$ with various cluster properties, we probe the origin of the high energy photons from these GCs. We report $L_{\gamma}$ is positively correlated with the encounter rate $\Gamma_{c}$ and the metalicity $\left[{\rm Fe/H}\right]$ which place an intimate link between the gamma-ray emission and the millisecond pulsar population. We also find a tendency that $L_{\gamma}$ increase with the energy densities of the soft photon at the cluster location. Furthermore, the two-dimensional regression analysis suggests that $L_{\gamma}$, soft photon densities, and $\Gamma_{c}$/$\left[{\rm Fe/H}\right]$ possibly span fundamental planes which potentially provide better predictions for the $\gamma$-ray properties of GCs.