Observation of Pulsed Gamma-rays Above 25 GeV from the Crab Pulsar with MAGIC

TL;DR

This study used the MAGIC telescope with a new trigger to detect pulsed gamma-rays above 25 GeV from the Crab pulsar, providing insights into the emission region and challenging existing models.

Contribution

Developed a new electronic trigger for MAGIC, enabling detection of gamma-rays above 25 GeV and constraining pulsar emission models.

Findings

Detected pulsed gamma-rays >25 GeV from Crab pulsar

High cutoff energy suggests emission occurs far out in the magnetosphere

Excludes polar-cap scenario and challenges slot-gap models

Abstract

One fundamental question about pulsars concerns the mechanism of their pulsed electromagnetic emission. Measuring the high-end region of a pulsar's spectrum would shed light on this question. By developing a new electronic trigger, we lowered the threshold of the Major Atmospheric gamma-ray Imaging Cherenkov (MAGIC) telescope to 25 GeV. In this configuration, we detected pulsed gamma-rays from the Crab pulsar that were greater than 25 GeV, revealing a relatively high cutoff energy in the phase-averaged spectrum. This indicates that the emission occurs far out in the magnetosphere, hence excluding the polar-cap scenario as a possible explanation of our measurement. The high cutoff energy also challenges the slot-gap scenario.