Search for VHE $\gamma$-ray emission from the globular cluster M13 with the MAGIC telescope

TL;DR

This study used MAGIC telescope observations to set upper limits on very high energy gamma-ray emission from globular cluster M13, constraining millisecond pulsar populations and particle acceleration models.

Contribution

First to provide VHE gamma-ray upper limits for M13, testing pulsar population and lepton acceleration models within the cluster.

Findings

No significant VHE gamma-ray emission detected

Limits constrain the number of millisecond pulsars in M13

Results suggest less efficient lepton acceleration than models predict

Abstract

Based on MAGIC observations from June and July 2007, we have obtained an integral upper limit to the VHE energy emission of the globular cluster M13 of $F(E>200 \textrm{GeV})<5.1\times10^{-12} \textrm{cm}^{-2} \textrm{s}^{-1}$, and differential upper limits for $E>140 \textrm{GeV}$. Those limits allow us to constrain the population of millisecond pulsars within M13 and to test models for acceleration of leptons inside their magnetospheres and surrounding. We conclude that in M13 either millisecond pulsars are fewer than expected or they accelerate leptons less efficiently than predicted.