MAGIC observation of Globular Cluster M13 and its millisecond pulsars

TL;DR

This paper reports on MAGIC telescope observations of globular cluster M13, setting upper limits on very high-energy gamma-ray emission to constrain millisecond pulsar populations and their particle acceleration models.

Contribution

It provides the first upper limits on E>140 GeV gamma-ray emission from M13, testing and constraining models of pulsar lepton acceleration.

Findings

Fewer millisecond pulsars than expected in M13.

Lepton acceleration in M13's pulsars may be less efficient than models predict.

No significant gamma-ray emission detected at E>140 GeV.

Abstract

Based on MAGIC observations from June and July 2007, we present upper limits to the E>140 GeV emission from the globular cluster M13. 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/or surrounding. We conclude that in M13 either millisecond pulsars are fewer than expected or they accelerate leptons less efficiently than predicted.