Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Measurement of the Iron Spectrum with the MAGIC Telescopes

M. Molero, S. Mangano, C. Delgado

TL;DR

The paper tackles measuring the iron component of the cosmic-ray spectrum at TeV–tens of TeV energies using ground-based Imaging Atmospheric Cherenkov Telescopes. It introduces and applies the Direct Cherenkov light technique with the MAGIC telescopes, coupling Random Forest energy reconstruction to a two-step DC-based event selection that isolates iron-induced showers. The study reports the first MAGIC detection of DC-light from iron and identifies 287 iron candidate events in the 10–60 TeV range, with a preliminary total systematic uncertainty of 32%. This work demonstrates the feasibility of DC-light measurements with MAGIC and provides a foundation for refined iron spectroscopy with larger datasets and advanced analyses, complementing space-based observations and extending high-energy iron measurements to the TeV regime.

Abstract

Iron cosmic rays represent the most abundant heavy nuclei at energies above 1 TeV, with their production thought to be primarily originated by astrophysical sources. Therefore, measuring the iron spectrum provides crucial insights into the origin, acceleration, and propagation mechanisms of cosmic rays. While recent results from space-based detectors have revealed unexpected energy dependences in the GeV-TeV range, these measurements are limited by low statistics at higher energies. At energies above a few TeV, ground-based detectors, such as the Major Atmospheric Gamma Imaging Cherenkov (MAGIC) telescopes, become more effective due to their large collec- tion areas, enabling them to extend and complement the capabilities of space-borne instruments. In this work, we apply the so-called direct Cherenkov technique, which accounts for the radiation emitted by charged particles before the cascade develops in the atmosphere, with MAGIC to identify iron-induced air showers and distinguish them from those produced by lighter cosmic-ray species.

Measurement of the Iron Spectrum with the MAGIC Telescopes

TL;DR

The paper tackles measuring the iron component of the cosmic-ray spectrum at TeV–tens of TeV energies using ground-based Imaging Atmospheric Cherenkov Telescopes. It introduces and applies the Direct Cherenkov light technique with the MAGIC telescopes, coupling Random Forest energy reconstruction to a two-step DC-based event selection that isolates iron-induced showers. The study reports the first MAGIC detection of DC-light from iron and identifies 287 iron candidate events in the 10–60 TeV range, with a preliminary total systematic uncertainty of 32%. This work demonstrates the feasibility of DC-light measurements with MAGIC and provides a foundation for refined iron spectroscopy with larger datasets and advanced analyses, complementing space-based observations and extending high-energy iron measurements to the TeV regime.

Abstract

Iron cosmic rays represent the most abundant heavy nuclei at energies above 1 TeV, with their production thought to be primarily originated by astrophysical sources. Therefore, measuring the iron spectrum provides crucial insights into the origin, acceleration, and propagation mechanisms of cosmic rays. While recent results from space-based detectors have revealed unexpected energy dependences in the GeV-TeV range, these measurements are limited by low statistics at higher energies. At energies above a few TeV, ground-based detectors, such as the Major Atmospheric Gamma Imaging Cherenkov (MAGIC) telescopes, become more effective due to their large collec- tion areas, enabling them to extend and complement the capabilities of space-borne instruments. In this work, we apply the so-called direct Cherenkov technique, which accounts for the radiation emitted by charged particles before the cascade develops in the atmosphere, with MAGIC to identify iron-induced air showers and distinguish them from those produced by lighter cosmic-ray species.
Paper Structure (9 sections, 2 equations, 3 figures, 2 tables)

This paper contains 9 sections, 2 equations, 3 figures, 2 tables.

Table of Contents

  1. Introduction
  2. The MAGIC Telescopes
  3. Datasets and MC simulations
  4. Analysis Method
  5. Energy Reconstruction
  6. Data Selection
  7. Systematic Uncertainties
  8. Conclusions
  9. Acknowledgements

Figures (3)

  • Figure 1: Direct Cherenkov Ratio ($Q_{DC}$) for M2 and for the energy range 15.85 < E/TeV < 25.12. Figure (a) shows the comparisons of $Q_{DC}$ for iron simulated events with respect to p and he simulations. Figure (b) compares iron with oxygen, magnesium and silicon.
  • Figure 2: Intensity of the Direct Cherenkov Light ($I_{DC}$) for M2 and for the energy range 15.85 < E/TeV < 25.12. Figure (a) shows the comparisons of $I_{DC}$ for iron simulated events with respect to p and he simulations. Figure (b) compares iron with oxygen, magnesium and silicon.
  • Figure 3: Measured iron event shower in real data with evident Direct Cherenkov light in M1 (a) and M2 (b) . The black triangle and dot show the reconstructed shower direction and c.o.g. respectively, whereas the two red perpendicular lines within the ellipse correspond to the Width and Length obtained from the standard Hillas parameterization. The reconstructed energy of this event is 30.30 TeV.